© Copyright B. A. J. Clark, Australia 1999, 2000. The copyright owner hereby gives permission for this entire text including this notice to be copied, stored, and transmitted in full by electronic means and printed in full by any person(s) or organisation(s) interested in environmentally acceptable outdoor lighting. For a free electronic copy of the latest version, check the website of the Astronomical Society of Victoria Inc., Australia, at <http://www.gsat.edu.au/astrovic>. Resale of this document in any form is prohibited.

Please quote LP14.DOC, version of 19 July 2000, if you have any constructive feedback to send via <bajc@alphalink.com.au>.

Outdoor lighting in Australia often lags well behind world’s best practice. Far too much unused and waste light illuminates the night sky, needlessly damages the environment or is otherwise obtrusive. Producing this light wastes energy and unnecessarily increases greenhouse gas emissions. Artificial sky glow, one of many undesirable consequences, hampers astronomical observation and research and degrades the beauty of the night sky. Careless installation and overuse of outdoor lighting adversely affects the environment and can degrade human health, safety and recreation. The problem is growing at an alarming rate. The trend must be reversed, not just halted.

Outdoor lighting improvements are frequently proposed in ignorance for crime reduction. Genuine improvements can lead to economic and environmental advantages, but crime is a social problem, not a lighting problem.

Control of obtrusive lighting is relatively simple and economical. Control measures have low technical risk and will result in a more attractive, comfortable, safe and healthy visual environment for residents, workers, shoppers, travellers and tourists. Comprehensive regional outdoor lighting codes, or better, a national code, could assist commerce, improve livability and assist Australia to meet its greenhouse gas emission targets.

Environmental requirements in the 21st century will require urban and rural outdoor artificial lighting to allow comfortable and safe vision while conserving energy and minimising ill effects on the environment and human health. Early achievement of this in specific locations would assist development and prosperity while providing exemplary guidance for other areas. Future outdoor lighting installation and use must be based on a justifiable balance between economics, user needs and environmental factors. The result should epitomise technological effectiveness, environmental care, comfort and elegance, and thereby assist tourism, trade and business.

Outdoor lighting has to satisfy the shared and specific needs of three main groups: residents, users of the area, and tourists/travellers. This report describes desirable characteristics and applicable constraints.

Outdoor lighting should comply with established standards of illumination with attention to improved uniformity and reduced discomfort glare and disability glare. The single most important improvement that could be made to existing outdoor lighting is to reduce or eliminate glare by appropriate shielding of all light sources.

Intensity and luminance maxima in the artificially lit visual scene need to be limited relatively and absolutely. Generally the upper hemisphere should be the brighter wherever practicable. In shopping areas, verandas and awnings can help to achieve this by utilising otherwise wasted upwelling light from shop windows. Illumination with good colour rendering and minimal glare will generally be good for all, including persons with subnormal vision or colour vision deficiencies or both. Nevertheless, lighting with poor colour rendering can be advantageous in some circumstances for economy, to minimise effects on observational astronomy and as a graffiti deterrent.

Intense or continuous lighting is generally unnecessary for personal or property security, and may even encourage crime because fear of crime is allayed and commission is facilitated. In some circumstances, darkness can inhibit crime. Especially when displacement is taken into account, there is no reliable evidence that more or brighter outdoor lighting reduces crime rates. Seclusion rather than dim lighting favours crime. Crime is a social problem, not a lighting problem. Coloured lighting to discourage illicit drug injections merely displaces the activity, advertises the area for drug dealers, and engenders unease for law-abiding citizens and visitors.

Far more care than hitherto is required with sports lighting installations to minimise light spill into nearby roads, parks, residential areas and upwards. Excessive glare can be a traffic hazard. Too much stray illumination at residential property boundaries is highly undesirable and needs to be minimised for the health and well being of residents. Upwards spill should be blocked to avoid degrading the visibility of natural phenomena in the night sky.

Adverse effects of excessive outdoor stray light at bedroom windows include sleep disturbance and sleep loss. Artificial light at night, including dim light inside bedrooms at night, is actively being investigated as a health risk factor. It is better to deal with the problem at its source instead of having to install blackout blinds.

Much of Australia lags badly in the application of world’s best outdoor lighting practice. Several states and many cities, towns and counties in the USA have laws to control obtrusive lighting and the list is growing steadily. Most US states use at least some fully shielded lighting on roads and highways. Several other countries as well as many places in Australia, particularly in the Australian Capital Territory and New South Wales, are introducing light pollution laws or already have them in place. There is little technical risk in following such well established procedures.

Cutoff luminaires are operable light fittings with shielding to reduce glare and upward light spill. Examples are ‘cobra head’ luminaires modified to incorporate a flat lens (‘aeroscreen’) and ‘shoe box’ cutoff luminaries. Limits for glare from road and path lighting in Australia are set in the Australian and New Zealand Standard AS/NZS 1158 but compliance is subject to long delays. Other existing outdoor lighting in Australia is usually glary, especially along the approaches to towns and cities. Substantial improvement is possible by widespread application of AS 4282-1997, Control of the obtrusive effects of outdoor lighting. Glare inhibits tourism, makes cities and towns less desirable places for their own people as well as for visitors, and degrades the environment.

Freedom from visual discomfort and visually obtrusive objects or features promotes visual ease, adds to the quality of life and is good for business.

Australian capital and provincial cities could all doubtless benefit from having their own unique visual feature. Natural or historical features already exist in some cases. Attempts to contrive others, as by floodlighting infrastructure, often fail or bring discredit for environmental reasons. The upwardly directed floodlighting of Melbourne’s Bolte Bridge and Sydney’s Anzac Bridge have resulted in many objections and protests by members of the public against light pollution, light trespass and energy wastage including unnecessary production of greenhouse gases. The spill light has also been widely deprecated for its possible and demonstrable adverse effects on health of residents, pets and wildlife, as an aviation hazard and in hampering night sky observation.

Although the technique is already in limited use in some cities of other countries, Australian cities and towns could make a favourable visual impression with elegant minimalist edge lighting schemes (‘tracing’). For a successful outcome, building floodlights, advertising sign lighting and window light spill must also be controlled to a much greater extent than is currently specified in AS 4282-1997. There appears to be a need for regional or national outdoor lighting codes of practice to complement AS 4282 and AS/NZS 1158.

The southern hemisphere sky is a richer natural and telescopic spectacle than its northern counterpart. Unnatural urban sky glow caused by light pollution drastically reduces the visibility of most celestial objects, degrades aesthetic enjoyment and hinders scientific and recreational astronomy. In Australia’s worst cases this pollution measurably affects the night sky to as far as hundreds of kilometres away. Northern hemisphere investment in inland Australian observatories is threatened by the spread of light pollution.

Tourists from the northern hemisphere often expect to see the Southern Cross soon after they arrive, but at Sydney and Melbourne the fifth bright star is often blotted out and the fourth star may be hard to see. The southern Milky Way and the Magellanic Clouds are generally invisible. Australia is thus thoughtlessly damaging an important tourist attraction. Tourists can experience insecurity if sky glow and outdoor lighting glare hinder orientation by reference to familiar parts of the sky.

Light pollution can be minimised simply and inexpensively when the problem is dealt with appropriately. Better utilisation of the available light can facilitate lamp wattage reduction, but few retailers, advertisers, academics, building owners and municipal bodies in Australia appear to be aware of this. Voluntary compliance with AS 4282 has failed so that mandatory application is required. This would also assist heritage compliance and tourism in the case of several historic Australian observatories.

Unwanted illumination across property boundaries is called light trespass. It can produce adverse effects ranging from sleep disturbance and loss, visual problems, pedestrian falls and road accidents. Light trespass control should be a general pro-active commitment instead of a reactive response to complaints.

Brilliantly lit advertising signs and commercial premises such as petrol filling stations and convenience stores are major sources of light pollution, light trespass, glare and visual unease. Illumination ‘races’ between commercial or advertising rivals generate ‘ratcheting’ responses and increasing environmental damage. Decorative floodlighting should only be used if it can be justified in the public interest and then it should be temporary, minimal and always by downwardly directed lighting fully shielded against light spill. Mandatory controls for all of these are required as AS 4282 does not go far enough and voluntary compliance is often weak or absent.

Internal light escaping from windows contributes to light pollution and light trespass. Height of the window above surrounding terrain and structures tends to increase the effect because of reduced obstruction. Room presence sensor switches, opaque blinds and tinted window glass can variously contribute to the minimisation of escaping room light. One or more of such features should be required at the planning stage for all new buildings and refurbishments.

Light pollution in cities and towns can affect trees and other flora in street margins, nature reserves, gardens and parks, although quantitative details are sparse. Severe urban light pollution can increase night illumination by as much as four orders of magnitude and diminish the amplitude of the annual, lunar and daily light cycles, factors of evolutionary importance for life on Earth. Marine and aquatic life can be affected by light pollution. Subjecting rivers, beaches, bays and coastal seas to avoidable direct or scattered illumination is environmentally irresponsible. Where there is a public demand for summer night beach illumination, it should be dim, shielded to restrict coverage to the minimum and curfewed.

Obtrusive lighting can disturb the behaviour of nocturnal animals. Upwardly directed floodlighting of trees disorients and dazzles birds and tree-climbing mammals. Permanent photochemical retinal damage can occur. Temporary and even permanent vision loss is possible when powerful upwardly aimed spotlights are positioned where pedestrians can look straight into the beam or can otherwise be subjected to inadvertent direct exposure. Lighting authorities have a duty of care in preventing all such exposures.

High levels of artificial ambient light curtail animal sleeping times. Sleep-wakefulness patterns appear to change in marine and coastal bird species. Seagulls and other birds congregate above brightly uplit structures such as bridges and buildings, often constituting a bird-strike hazard to low overflying aircraft. Some circling birds die from exhaustion. In North America each year, about 100 million migratory birds die from collisions with illuminated high buildings and towers. Other birds are deflected from their destination by injury or disorientation or both and fail to breed. Brightly lit high buildings and towers in Australia are no less likely to be bird hazards.

The human species depends on biodiversity. A century of outdoor lighting has already reduced moth numbers, probably favouring urban pest insect species such as flies and cockroaches. Replacement of existing lamps by low pressure sodium (LPS) lamps, when appropriate, could be expected to reduce adverse effects on insect populations as well as to improve the cultural benefit from some lighting installations.

The Government’s commitment to climate protection would be supported by avoiding the energy waste associated with light pollution and light trespass. The ACT and NSW appear to be ahead of other parts of Australia in this respect. Light sufficiently intense to be seen at night as beams or to light up clouds sends the message that Australia has no genuine commitment to greenhouse gas reduction. They can be an aviation hazard. A complete ban on commercial sky beams is environmental commonsense.

Leaving empty offices lit after hours is wasteful and contributes unnecessarily to greenhouse gas emissions. Penalties should be applied.

Lighting codes for Australia should favour the introduction of desirable new forms of artificial lighting. Light polluting items in the present inventory, including all mercury vapour lamps, should be discarded. Low pressure sodium lamps are becoming less widely used for road lighting because they sometimes fail prematurely but they have advantages of economy and minimal effects on wildlife and gardens. Efficient stray light rejection by filters is possible in astronomical observations when LPS replaces other lamp types in locations near observatories. Parks and gardens path lighting could desirably be by fully shielded LPS downlighting to comply with the AS/NZS 1158 limits on upward waste light. Motion detection switching is desirable as energy savings are possible. LPS ‘security’ lighting is thought to deter graffiti vandals because of its poor colour rendition.

More concern and active coordination among authorities in Australian states is needed to control btrusive lighting. It could be appropriate for state capital city councils to lead by example. But state-wide campaigns might be better led by each state’s environment protection body or energy saving authority. The charters of such bodies might need to be modified to include obtrusive and wasteful lighting. A federal lead could help to minimise divergence between the approaches of individual states.

Proposals for urban outdoor decorative lighting typically ignore environmental, health and safety concerns. Local government authorities should make compliance with all parts of AS/NZS 1158 and AS 4282-1997 mandatory where this is not already set by existing laws, and compliant outdoor lighting plans should be a necessary condition for the issue of building permits. Regional comprehensive municipal outdoor lighting code models, or better, a national model, should be developed as a basis for widespread adoption in Australia. Many other places in the world already have such codes in place and the texts are readily available to help in writing codes for Australian application.

Given that Australia has international obligations to limit its greenhouse gas emissions and the fact that the larger cities at least are already subject to the ill effects of perpetual artificial twilight all night, the amount of electrical energy used for outdoor lighting needs not just to be capped at its present value but substantially reduced by government action at all levels. No new outdoor lighting installations should be permitted unless compensated by removal from service of several installations of equivalent or greater energy consumption.

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This document is a development of one originally prepared as a guide for Melbourne City Council and its staff concerned with developing a new outdoor lighting strategy (Clark 1999). It is now applicable to Australian cities, towns and rural settings generally, although many of the examples given still relate to Melbourne. The pervading rationale is that outdoor lighting of cities, towns and rural areas can be arranged to provide comfortable, safe and effective vision with economy while conserving energy and minimising environmental ill effects. For state capitals, the achievement of these aims has twofold importance: firstly it would assist continued development and prosperity, and secondly it would also provide exemplary guidance for suburban areas, and cities and towns. This potential broad application and influence underscores the necessity for Australian outdoor lighting strategies to have a justifiable evolving balance between three main factors: economic and commercial pressures, user needs, and environmental sustainability, bearing in mind that the environmental constraints look set to become increasingly important during the 21st century.

Artificial lighting has been a key factor in the development of civilisation. Its outdoor component has made a substantial contribution but mismatches with user needs and environmental shortcomings have too readily been overlooked in the past. By increasing attention to these issues now, future outdoor artificial lighting can be developed in a way that will optimise its value. As with all design, and especially where there is a human user component, compromises are inevitable but this certainly does not preclude a highly satisfactory outcome.

At present, the main environmental problems of outdoor lighting stem largely from its enormous rate of proliferation. Although the increased usage has undoubted social benefits there is no guarantee that artificial light at night is entirely benign. It is certainly evident that the night sky, once a magnificent natural spectacle even from urban centres, is often now only a washed-out image of its former glory. Most of this loss has occurred in less than two generations. The trend must be stopped and reversed before it does irreparable damage to human advancement and to biodiversity. The goal is achievable and it can bring many other benefits. This document provides a basis for an outdoor lighting strategy for the new millennium.

Considerations of artificial lighting may benefit from comparisons with natural lighting. Useful sources of information on sun and natural sky luminance and terrain illuminance are Hulbert (1949), Levi (1980), Middleton (1952), Middleton and Mayo (1952), Karandikar (1955), Wesener (1967), Biberman (1971), Gordon, Edgerton and Duntley (1975) and Garstang (1985).

Sky beams belong to World War 2 and glorified gambling dens. Megalights are ills of megacities. Brilliant floodlighting and rainbow colours are evocative of theme parks. Bud lights and fairy lights look fine in Fairyland. Harsh lighting glare is symbolic of overcrowding and poverty of the Third World. Capital cities known for their colour cacophonies of visually interlocked neon signs are welcome to keep these things, just as the great urban conglomerates of the richest nations have their perpetual twilight as a modern equivalent of the smoke of the industrial revolution. The lighting of Australian cities should epitomise advanced technology, quiet efficiency, environmental cleanliness, comfort and elegance. A razzle, dazzle, tinsel and glitter image will be for the urban dinosaurs of the coming age. If Australia does indeed help to set the worldwide urban lighting fashion for the 21st century, this should have a positive effect on tourism, trade and business.

On a less euphoric note, this document incorporates the belief that to excel, catching up with the leaders is a necessary prerequisite to surpassing them.

Full realisation of the benefits of a rational and unified national approach to outdoor lighting will require lighting details to be a mandatory in all future development planning and building permits.

Sufficient outdoor lighting needs to be provided for the activities of using a city, but it is not at all obvious how ‘sufficient’ is determined. City users vary greatly in their capabilities and requirements. For example, although many people are able to read newspaper text in full moonlight, that level of illumination could hardly be set as adequate for reading a bus ticket let alone the fine print on a parking ticket. On the other hand, the belief of some entrepreneurs that ever more light is better in a commercial area can be demonstrated as similarly ill-founded. Uniform luminance of about 4000 cd/m², typical for a white surface in full daylight, is a borderline value between visual comfort and discomfort for young persons. The threshold discomfort value falls with age, by a factor of about three in a life span. The trend for brighter artificial lighting of commercial areas, including shop windows, is already becoming a problem for older persons. The aging of the population will increase the occurrence of discomfort unless the trend for excessively bright lighting is curbed.

Lighting levels developed by or for national and international bodies concerned with light and vision are generally reliable guides and should not be exceeded unless special reasons for variation can be demonstrated (eg IDA IS12 1996, IDA IS77 1998, IESNA 1999). Lower values within recommended ranges may be quite satisfactory in practice. Lower limits may sometimes seem surprisingly small: eg Caminada and van Bommel (1990) recommended only 0.8 lux on vertical planes at eye height for pedestrian areas in residential precincts. But this is still several times brighter than full moonlight.

Illuminance limits for public lighting (roads, footpaths etc.) are given in the Australian and New Zealand Standard AS/NZS 1158 (SA 1999), along with maximum values for Upward Waste Light Ratio of lumnaires. But standards generally specify the lowest acceptable performance so that higher performance may be possible and even desirable. This can often be the case in relation to uniformity and glare reduction. Nevertheless, economic and other practical factors limit tend to limit such improvements.

Excessive ambient light levels from commercial lighting adjacent to city roads introduce glare, along with unpleasant and possibly hazardous rapid changes in adapting luminance for drivers when traffic is moving quickly. The problem is exacerbated by the fact that many road vehicles now have tinted glazing: not only is the permitted installed transmittance ill defined and too low but further variation, up or down, is likely with different light sources as the spectral properties are not defined at all (Clark 1996). The Massachusetts Medical Society has emphasised the importance to older drivers of limiting glare from road lighting (MMS 1999).

‘Turning night into day’ in a city by brilliant lighting might be the goal of the lighting industry but is not the way to make the city more attractive, safer or healthier. The problems of excessively illuminated objects and inadequately shielded intense light sources adjacent to urban roads are not necessarily dealt with adequately either in AS/NZS 1158 or in the obtrusive lighting standard AS 4282. For example, industry objections resulted in 4282 being inapplicable to illuminated buildings and billboards. Additional controls may therefore need to be imposed in the interests of traffic and pedestrian safety.

Other adverse consequences of excessive outdoor lighting are mentioned below.

Australia has an aging population. Older persons have smaller eye pupils than young persons. Older persons need more light to achieve the same level of visual performance, insofar as equality is even possible. But visual performance for all is often far from optimum with typical outdoor lighting at present, largely because insufficient attention is given to reducing glare. By minimising glare, not only can visual performance generally be better but a substantial improvement in visual comfort is possible. Better seeing also improves pedestrian mobility safety.

The single most important improvement that can be made to urban outdoor lighting is to eliminate glare. This requires all light sources to be shielded so that intensely bright areas such as lamps, reflections of lamps and over-illuminated areas close to lamps are not seen in normal circumstances. Not only would this greatly improve the amenity of areas so lit but unfortunate people with significantly reduced vision, as much as 10% of the population, would often be able to see better than is usually the case at present.

Glare-free lighting (more strictly, reduced-glare lighting) is far more likely to be an attractive factor for retail, commercial and recreational precincts than is brighter, typically glary lighting. A glare-free visual environment can only be achieved by limiting the luminance contrast range in the visual scene and this sets strict limits on the intensity and luminance maxima. In general, lamps require full anti-glare shielding. Illuminated surfaces should not exceed specific relative values of luminance set as a multiple of the mean luminance of the visual background. Maximum absolute values of intensity and luminance also need to be applied to prevent the environmental lunacy of each billboard owner trying to outshine all others in the vicinity.

Life evolved on Earth with the sky usually being brighter than the terrain, by night as well as by day. For humans the normal and more comfortable order is therefore to have the upper visual hemisphere brighter than the lower. This is more or less the case in artificially lit building interiors but it is more difficult to achieve outdoors. In the case of floodlit outdoor sports grounds, for example, the upper field contains glaring lights surrounded by the apparently black sky. The lower field includes the brightly lit playing surface. Despite the unnaturalness of this arrangement, glare is probably the more potent cause and more readily recognised reason for user discomfort. The role of the dark upper background is confounded by its contribution to glare.

The lighting naturalness outdoors in retail sectors of towns and cities at night could be improved by making more effective use of verandas and awnings in the footpath lighting scheme. Light colours on the underneath parts of verandas and awnings maximise the beneficial effect, even if these parts are not deliberately lit. Verandas and awnings tend to make good use of the otherwise wasted upwelling light from shop windows, so their installation or reinstallation should be encouraged. For footpaths without closely adjacent buildings, this is a justification for walkway covers to have light-reflective rather than transparent roofing. It is also an indication, if any were needed, that day and night illumination and the built environment are interdependent and not always in harmony.

About 8% of all males and 0.4% of all females in Australia, including persons with subnormal vision, exhibit a congenital (inherited) reduction in colour vision. Roughly half of all congenital colour vision deficients will accept colour matches made by colour normals and the remainder show characteristic variations. In the present context, colour recognition, discrimination and matching are of most importance in a retail setting, usually indoors, where the lighting is under the control of the retailer or building owner.

Although generally of less importance outdoors, wherever colour recognition and discrimination have some legitimate importance they should not be made substantially more variable or uncertain for anyone by the use of lighting with a low colour rendering index. Unfortunately the most efficient and environmentally acceptable lamps for outdoor use, low pressure sodium (LPS), also have poor colour rendering properties. LPS has lost favour in recent years as high pressure sodium (HPS) lamps with better colour rendering and fewer untimely failures have come into use. Unfortunately, HPS lamps are not as energy-efficient as LPS lamps are. While there may be good economic reasons to reduce the number of lamp types in the inventory of public lighting authorities (eg Gray and Price 1996), LPS is so superior from an environmental viewpoint that its use should still be considered in combination with other lamps and ambient illumination (from car headlamps, for example) that allow adequate colour rendering in the particular circumstances. LPS road lighting has a reputation for causing confusion with amber traffic lights but the problem is largely solved if the LPS lamps are properly shielded (IDA IS13 1996). The user consequences of premature failure of LPS can be reduced by installation of multiple lamps.

About a quarter of congenital colour vision deficients, the ‘protan’ types, have a substantially reduced sensitivity to red light. As a result, what others may see as a stepless transition in illuminance between areas lit by different lamp types (eg conventional fluorescent to incandescent or high efficiency fluorescent) may be perceived as a pronounced spatial change in light levels by about 2% of the male and 0.1% of the female population. The use of coloured lights or surface colours for colour coding without additional redundant cues can produce unintended and possibly hazardous responses. Lighting designers need to understand and, as far as is practicable, to allow for the special problems of colour vision deficients as well as for persons with reduced visual capabilities.

Larger Australian cities typically have sports grounds with lighting arrangements capable of achieving the large vertically down components of luminous flux considered desirable for television broadcasts - an illuminance of 1000 lux on the ground is typical. Sports grounds with illumination systems of lesser capability and size, all the way down to single backyard tennis courts, are common in towns as well as cities.

In general the lighting systems are reasonably effective for performers and spectators, although far from being glare-free or mimicking natural daytime illumination. Although the needs of users of these facilities are more-or-less met, most of the lighting installations fall well short of what is desirable in terms of minimising light spill near and above the horizontal, let alone outside the property boundaries. In cases such as the Melbourne Cricket Ground, the light spill is so pronounced that different public lighting strategies are appropriate in the vicinity outside the grounds depending on whether the sports lighting is on or off at the time. It may also be that the disability glare levels fail to meet the limits specified more recently in AS/NZS 1158.1.1:1997. Both of these aspects indicate how sports light spill may be counter to the needs of other city users in the vicinity.

The local government authority concerned in each case should insist on much stricter control of light spill from such facilities in future, particularly as luminaires with far less stray light have been developed in the years since much of the lighting was first installed. Effective full cutoff or better fittings (eg ‘shoebox’ types) are available commercially for most applications. Care is required to ensure that the luminaires are installed at the design angle instead of being inappropriately tilted or canted as is often done in ignorance. In the first instance, compliance with the relevant Australian Standards should be mandatory. Additional control of light spill should be encouraged or imposed where appropriate.

Direct light spill from the luminaries is not the whole story. Especially in the case of large brightly lit sports fields, the field itself is a powerful source of light radiating above the horizontal. Surrounding terrain and the built environment may be subject to light trespass from this source as well as from floodlight spill. The upwelling light contributes to urban skyglow and illuminates any cloud in the vicinity. Some of the skyglow and cloud light is returned to the terrain where it increases the ambient artificial illumination. The amount of light involved can be far from trivial: for example it can be brighter than moonlight illumination, which has already been considered as a supplement to artificial lighting of streets (Vingrys and Smith 1994).

Measurements by the writer at Royal Park (about 188 ha of open parkland about 2.5 km north of the Melbourne CBD) in March 2000 indicated that the horizontal ambient illuminance on a moonless night could be about 1 lux in the presence of cloud. At this location, calculated increments to the ambient illuminance from a single nearby hockey pitch lit to 1000 lux could possibly be as high as 5 lux when the sky was overcast. Contrast this with natural conditions of a similar moonless overcast sky and no artificial light at night: the difference in ambient illumination could be as much as a factor of ten thousand. The immediate problem here is the extent to which animals in the adjacent Melbourne Zoo and surrounding parkland could be affected. A principle arising from the investigation is that existing ambient lighting in the vicinity of proposed sports lighting should be added to the expected light spill in determining whether the new lighting will be tolerable.

Effects of light pollution on animals, and curfews for sports and other outdoor lighting, are discussed below.

In an attempt to limit urban sprawl, some state governments have been encouraging people to move into city apartments in recent years. Many cities and large towns are steadily gaining residents. Urban residents have many lighting needs in common with those who are non-residential users of urban facilities. This section includes discussion on whether they also have some special lighting needs of their own.

Understandably, most people want crime reduction regardless of where they live. City residents tend to have a relatively large aggregate exposure time to high crime rate areas in or near the inner city. City residential building entrances are often situated away from the main thoroughfares and are generally not as brightly lit. City residents might therefore believe themselves to be at increased risk, especially if outdoor lighting in their locality fails or is reduced. There is a widespread belief that crime is associated with darkness, although the facts indicate quite differently (eg ICOLE 2000).

A related almost universal but false notion is that more and brighter outdoor lighting prevents or reduces crime and reduces the risk of crime. This myth is fostered even in AS/NZS 1158.3.1: 1999 on public area lighting, and Standards Australia endorses this in its advertising. Of course, extending the belief to its ultimate stage means there should be little or no daytime crime, but that is far from the facts. For example, 54% of violent crime in the USA occurred between 6 am and 6 pm, and only 20% of rapes involve unknown assailants at night (BJS 1999). Only 35% of all burglaries in the USA are reported to have occurred at night, or 48% of all burglaries for which the time of occurrence is known (UCR 1996). During the power blackout that affected Auckland in New Zealand for several weeks in early 1998, press reports stated:

The National Institute of Justice presented a large report on crime prevention to the US Congress in February 1997 (Sherman, Gottfredson, MacKenzie, Eck, Reuter and Bushway 1997). The following quotes are from ‘Conclusions for Open Urban Places’ in Chapter 7:

Findings that more lighting reduces crime appear mostly to be confined to studies that are financially supported by lighting-associated companies or organisations (eg Lighting.com 1999). Other cases of pro-sponsor bias are known in industry-sponsored research; for example, in research reports sponsored by the tobacco industry claiming that cigarette smoking does not cause lung cancer and other diseases. Another example is that of reports claiming that car windshield and window tinting is not a road safety hazard: generally these have been done by or paid for by the vehicle industry while many more papers from independent vision researchers reach the opposite conclusion (Clark 1995).

Historically, urban crime rates have increased together with the growth in urban outdoor lighting although this, by itself, does not indicate a causal relationship. In particular, large fluctuations in crime during the 20th century appear to have no counterpart in the steadier growth of lighting, although both quantities grew substantially over the ten decades. In some more specific studies, crime actually increased as ‘better’ lighting brought more people into a busy area in the mistaken belief that they were now safer. Similar results have been observed when increased lighting has encouraged individuals to venture into an area that was previously shunned as secluded and unsafe. In other cases there have been relatively small displacements of crime to adjacent areas that are not necessarily darker. Even an announcement of planned lighting improvement has resulted in a displacement of this sort.

There is no doubt that displacement of crime sometimes occurs following outdoor lighting changes intended to reduce crime. As there is no overall crime reduction benefit, it is a government responsibility to block such wasteful and antisocial actions. The simplest way of doing this is by mandatory application of appropriate regional lighting strategies (ie statewide or municipal). What happens at present is that any neighbouring areas affected by crime displacement tend to respond by applying their own lighting changes, setting in motion a perpetual brighter lighting competition in the region with the inevitable outcome of environmental degradation, reduced quality of life and at least as much crime overall.

Vandalism can actually be reduced by making areas dark: vandals apparently need or like to see the damage they cause (IDA IS 54 1997, King 1995). A similar effect of darkness in inhibiting the incidence of burglaries has been explained as a result of the attention-drawing factor created when a burglar has to use hand-held lights such as matches or torches (flashlights) to see well enough to break in.

Crimes other than burglary are also generally more difficult to commit in darkness and again the use of hand-held artificial light sources tends to attract attention. Dark alleys, sideways, parks etc in an otherwise brightly lit area may favour the concealment of lawbreakers. However there is often enough ambient stray light to improve visibility from more brightly lit areas if minimal supplemental lighting is used. Nevertheless, comparable or better results are often possible simply by ensuring that the more brightly lit area is glare-free. Seclusion rather than dim lighting favours crime. Most so-called security lighting currently in use has been installed to allay fear, with little or no consideration of glare, light spill, economy, efficiency or even effectiveness in reducing crime. High-glare outdoor lighting tends to provide deep shadows for criminals to hide in. Insofar as they might be needed at all, future security light installations need to be controlled much more closely to avoid degrading the overall quality of an urban lighting scheme. Actual security is thereby more likely to be improved than decreased (IDA IS104 1996). Several interesting discussions are available about campus lighting and crime in IDA IS23 (1996), IDA IS 27 (1997) and IDA IS 31 (1997). A related issue, the trend to excessively bright lighting at petrol filling stations and convenience stores, is discussed in IDA IS145 (1998).

In recent years, places such as alcoves, recessed doorways and public toilets with night lighting have become favoured areas for drug addicts to inject themselves. Owners of these areas have attempted to discourage this use by using saturated red- or blue-coloured lighting that reduces, or is supposed to reduce, the visibility of subcutaneous blood vessels. (Red light actually enhances the visibility of veins but reduces the visibility of arteries.) The strategy works only to the extent that it merely displaces some of the illicit activity to somewhere else, usually close by. It is easily defeated by addicts who outline targeted blood vessels beforehand with ballpoint pens. It also advertises the availability or presence of illicit drugs in the area and seems likely to make passers-by uneasy. Blue-violet light is the worst possible colour in terms of its effect on visibility, legitimate or otherwise, for anyone whose vision is affected by cataracts.

One of the arguments for more light for security is that video surveillance cameras (or closed circuit television, CCTV) can be used more effectively. For instance, video cameras have been installed at metropolitan railway stations in Melbourne. To allow the camera optics to operate well stopped down to give a large depth of focus, excessively bright high pressure sodium lighting has also been installed at the stations in reduced-glare fittings. But bright lighting is an ineffective measure for controlling crime, and video cameras appear either to be ineffective (KDIS 1997) or of limited value (Sherman et al. 1997, Chs 7 and 10)!

An indication of the extent to which outdoor lighting is out of control in Victoria, at least, is the almost inevitable installation of low-mounted security floodlights around every new industrial building. The economic and environmental costs of providing, installing and operating these floodlights are far from trivial and reduce industrial competitiveness, but there is no known actual security advantage. Electric lighting manufacturers, designers and installers as well as electrical power companies appear to have fostered the belief that there is such a thing as ‘security’ lighting and that it deters crime. Communications media, especially newspapers, often perpetuate this myth uncritically on the basis that it is common sense: ‘everyone’ ‘knows’ it to be true. Actually it is demonstrable only to the extent that people do tend to feel safer when there is enough light for easy seeing. The conclusion from many independent studies is that there is no clear overall effect of the amount of outdoor lighting on actual crime rates (Ramsay 1991, IDA IS51 1992, Shaftoe and Osborn 1996, IDA IS63 1998). Even when special attention has been directed at the rate of sexual assaults the findings have been no different.

Lighting merely allays the fear of crime. Crime is a social problem rather than a lighting problem. It is extraordinary how much public and private funding is wasted in Victoria and elsewhere through entrenched ignorance of these facts. Better, glare-free lighting is as appropriate for city residents as it is for anyone else. But everyone needs to understand that this may mean less and dimmer lighting than at present. Security lighting that is switched off unless triggered by motion or presence sensors is now in common use. The switching is commendable, but controls on maximum intensity, aiming angles and spill light are still necessary.

City buildings at night are generally bathed in light, sometimes deliberately by floodlighting but more often by waste light from windows of other buildings and shops, stray light from road and other public lighting, and vehicle lights, together with light reflected from roads, buildings and other objects as a result of the provision of culturally useful illumination. Large brilliantly illuminated advertising signs on nearby buildings can be a major source of obtrusive lighting for city residents. To all this must be added ambient illumination resulting from skyglow and illuminated clouds.

Residents and occupants in high city buildings, especially those in the higher floors, tend to dispense in many cases with the active use of curtains or blinds or both at their external windows and thereby obtain a clearer external view, day and night. The consequent outwards escape of internal light is readily obvious at night. Unoccupied offices left lit at night to give the impression that the organisation is rich and successful also further increase the amount of stray illumination on other buildings.

Stray and otherwise unwanted artificial illumination across property boundaries is called light trespass. Its adverse effects on building occupants excessively exposed to it range from sleep disturbance and sleep loss to discomfort glare and disability glare. Individuals affected may be unaware that their illnesses or lack of well being (‘ill being’) are avoidable let alone what the cause is. The quality of sleep certainly has a powerful effect on health (Dement and Vaughan 1999). Furthermore, the apparent summer day length experienced with modern amounts of artificial light at night often produces a carbohydrate craving in inadequately adapted individuals to prepare for the winter famine that never comes, leading to obesity and consequent related diseases (Wiley and Formby 2000).

Quinn, Shin, Maguire and Stone (1999) claimed that excessive room light during sleep in early childhood is associated with a high probability of myopia in later life. The light levels described in the study could readily be approached and possibly attained in city residential premises as a result of light trespass if blinds are not used or are inefficient. The claim follows observations of eye development changes in animals exposed to light at night. However, Zadnik, Jones, Irvin et al. (2000) and Gwiazda, Ong, Held and Thorn (2000) independently reported that they found no connection between myopia and ambient night-time lighting. In response,Stone, Maguire and Quinn (2000) pointed out confounding factors in these studies. Given the balance of evidence against the claimed myopia effect, no decision on light trespass reduction should be made on the basis of this effect by itself.

Textbooks have long maintained that the human body clock has a 25 hr free running period. But it is now known that the period is closer to 24 hours and that the discrepancy came from uncontrolled light exposure at night, an effect much larger than previously thought (Dement and Vaughan 1999). Follow-on research into insomnia will consider factors such as exposure to room light during sleep and consequent premature release of the hormones melatonin and cortisol (Recer 1999). Reduced melatonin levels occurred in elderly subjects suffering from insomnia (Garfinkel, Laudon, Nof and Zisapel 1995).

Melatonin production by the pineal gland in rats during sleep at night is reduced by the presence of artificial light (eg Shah, Mhatre and Kothari 1984). Melatonin is also known to suppress tumours and to influence estrogen levels. Rates of breast cancer in women fall with increasing degrees of blindness. Breast cancer rates are about five times greater in developed countries than in third world countries. These facts together have strengthened the hypothesis that artificial light at night, including dim light in bedrooms, is a risk factor for mammalian breast cancer (eg summaries in Science Service (1998) and The Independent (1999)).

At a workshop on light-at-night and electromagnetic fields as risk factors for breast cancer, it was reported that rats exposed to illumination as weak as 0.2 lux at night had a twofold increase in the rate of tumour growth compared with rats allowed to sleep in the dark (NAPBC 1998). However, other experiments indicated that more light than this is required to cause measurable effects on levels of the hormones thought to be involved. For example, exposure to 500 to 1000 lux for 1 to 2 hours before sleeping (a typical exposure of sporting teams in high-level and televised games at night) suppressed melatonin levels by 40 to 60%. This does not negate evidence relating breast cancer to light-at-night but it does affect reasoning about the processes that could be responsible for any such effect.

The workshop concluded that while the evidence for artificial light and light pollution as risk factors for human breast cancer at present is insufficient by itself to justify asking the government to mandate safety measures, some researchers consider the evidence strong enough to prompt them to take prudent safety measures in their own homes (NAPBC 1998). A ‘rule of thumb’ is that bedrooms should be dark enough for one’s hands to be invisible. Four relevant scientific papers published since the NAPBC workshop are either inconclusive or support the hypothesis (eg lower rates of breast cancer occur north of the Arctic circle where extended winter darkness alternates with long summer daylight). One conclusive disproof would end the speculation but this hasn't happened yet despite many attempts.

This raises the issue of effectiveness of methods of blocking external light at windows. Shutters, blackout blinds and heavy drapes can work well but they are not always regarded as fashionable. Reduction of bedroom interior luminances to the lowest of natural outdoor levels requires blackout blinds like those used for photographic darkrooms, but these would be inordinately expensive for many residents. If highly effective blocking is required because of excessive external artificial light, it would also attenuate the light of dawn and effectively delay the associated arousal effect. Persons who suffer from seasonal affective disorder (Mayo 1998) might then need to have dawn simulator lighting as well (LDL 1999)! Seasonal affective disorder appears to be associated with circadian dysrhythmia. Exposure to bright light in the morning appears to be an effective treatment, and is not in conflict with any need for darkness in bedrooms at night.

Tinted and reflectively coated window glasses are sometimes relied on by themselves to control inwards and outwards light spill but they are much less effective than ordinary blinds and they tend also to impair any external view out at night. The fitting of room presence sensors to switch off the lights in unoccupied rooms with undraped windows could reduce the spill light problem for nearby residents, and could well become compulsory for environmental reasons in due course. Venetian blinds can also help somewhat if deployed, even if left in the fully open position, but they are not universally popular for practical reasons such as dust collection. Apparently a recent fashionable equivalent is the use of garden-type shade cloth as drapes. One city resident persisting with this arrangement has reported using airliner-type personal eye shades to allow continuation of sleep after sunrise in summer.

In common with a wide range of environmental and industrial safety issues, and regardless of the incomplete state of knowledge in this area, the issue of light trespass in general is best dealt with by controlling the problem at its source rather than by mounting a defence at the final stage. Not least of the problems in doing this is to overcome the belief that artificial light is universally beneficial. This belief is a result of a century of advertising propaganda by the lighting industry, beginning with Edison himself (Dement and Vaughan 1999, pp 99-100; Wiley and Formby 2000, pp 28-29).

It seems fitting to end this section with quotes from some light/health researchers:

From estimates of ownership of astronomical telescopes and binoculars in Victoria, perhaps one in a hundred urban residents might have such equipment and an occasional desire to use it on the night sky despite limited facilities for doing so. By itself, this small proportion could hardly have a large influence in determining requirements for a city lighting code. However, a far greater proportion of the population has a casual or occasional interest in the night sky for aesthetic reasons, for special events such as lunar eclipses and meteor showers, and a need to see clouds and other indicators of present and approaching weather conditions.

Part of the sky might be visible from a window or balcony, but in present Australian cities the prospects of seeing much more at night than overhead cloud or the moon and bright planets are minimal because of excessive light trespass and the effects of stray light in lighting up the atmosphere, ie light pollution causing urban artificial sky glow. From anecdotes heard over four decades by the writer during astronomical telescope demonstrations for the public at the Old Melbourne Observatory, the present level of sky glow appears to affect residents and visitors in sufficient proportion and degree to provide yet another reason for controlling obtrusive lighting across the whole of Australia. Many individuals speak enthusiastically of the outback night sky experience but express surprise and unhappiness on learning that the rapid spread of artificial skyglow represents a tangible threat to this experience even far inland within the foreseeable future.

The slogan, ‘Night is a right!’ arose from this aspect but a much broader set of reasons supports it.

It is understood that during the term of his US Presidency, George Bush managed to have billboards removed from federal highways as a beautification measure, a remarkable achievement given the opposing commercial pressures. In most states of the USA, roads and freeways have been equipped to some degree with full horizontal cutoff overhead lighting which provides reduced glare conditions for vehicle occupants (IDA IS117 1997). The billboards and cutoff lighting measures can both be described as promoting visual ease, a term that encompasses freedom from visual discomfort and absence of visually obtrusive objects or features. Travellers who have visited numerous cities would be aware that cities vary greatly in attributes that allow visual ease, and that visual ease can be achieved without necessarily substituting blandness and boredom. Approaches to the central business districts (CBDs) of large Australian towns and cities are currently far from world’s best practice in this respect. A mandatory integrated urban lighting code specifying glare-free road lighting and no billboards visible from freeways and tollways would lead to a substantial improvement.

In cases where there is a sea approach to a city or town, careful attention is required to ensure that garish light shows along the foreshore are not specified in future planning schemes like they were in Melbourne’s now overturned ‘Gateway to the Bay’ proposal (DOI 1999). Improved road and public lighting under the appropriate part of Australian and New Zealand Standard series AS/NZS 1158, and compliance with AS 4282-1997, Control of the obtrusive effects of outdoor lighting (SA 1997), are recommended.

In March 1999 the NSW Department of Urban Affairs and Planning issued development regulations for much of Sydney Harbour and Parramatta River, the reasons for this including protection of the view from the water. Not only is AS 4282 to be observed, but lights must also be shielded from the water, directed downwards, and in some cases shielded from neighbouring properties. Externally illuminated advertising signs must only be lit from above with lights directed downwards and away from the water (SOLIS 1999a). Despite this, authorities controlling Sydney’s new Anzac Bridge have overruled objections to intense uplighting of the structure.

When tourists and travellers arrive in the CBD, a glare-free high quality lighting scheme of moderate and reasonably uniform brightness would be a necessary condition to enable the impression of visual ease to continue indefinitely. When people feel at ease, it is good for business. The commercial import of this message should be clear.

The southern hemisphere of the sky is much more of a natural spectacle than its northern counterpart. The southern sky has the brightest stars, the brightest parts of the Milky Way, the two Magellanic Clouds (the nearest external galaxies) and the best constellations, arguably Scorpius and the Southern Cross. Telescopically it is also richer, which is why northern terrestrial hemisphere countries spend much of their astronomical research budget on equipping and operating large observatories in southern hemisphere locations including Australia.

One of the various reasons why ordinary tourists from the northern hemisphere visit southern hemisphere countries is because they have heard of the natural beauty of the southern sky, the Southern Cross etc and wish to see these things for themselves. Anecdotal evidence is that when they arrive at any of Australia’s cities they are generally disappointed because urban sky glow spoils the view. This is especially so in Melbourne and Sydney. From mid-city Melbourne on a clear night at present only a handful of stars can be seen- no Milky Way and no Magellanic Clouds. The Southern Cross is generally seen with its fifth bright star invisible. Recent large increases in light pollution in Melbourne combined with typical smog and haze tend to blot out one of the four main stars also, reducing the appearance to a far less remarkable triangle.

Lit windows without the blinds drawn in high city buildings add disability glare to the problem. Light pollution of the sky seen from the suburbs reduces only slowly with distance from the CBD. Although some data are available about the numbers of tourists and other travellers from the northern hemisphere who stay overnight in locations distant from the state capitals, local light pollution in most of the known tourist places is sufficiently bad to limit the proportion of visitors who do actually get to see a clear unsullied night sky. Most visitors therefore are likely to return home with far less enthusiasm than is possible for this aspect of their experiences. Ultimately all Australians will continue to lose out unless the situation is turned around dramatically.

Anecdotally it is also known that some visitors also try to establish or monitor their orientation at night by reference to familiar sights in the sky such as the Seven Sisters, the Twins, Orion’s belt and sword (The Pot to many of us in the southern hemisphere) and so on, but again they mostly encounter difficulty because of disability glare and artificial sky glow. For instance, The Pot may not be recognisable when most of its handle is invisible. Being confident about knowing one’s location and direction engenders a feeling of security. Conversely, uncertainty of orientation is conducive to unease and hardly an incentive to a longer stay or return visits.

Many cities in the world have an appearance or feature that is unique and identifying. In some cases it is a night image. The feature is not necessarily good or positive, as in the case of jumbled over-lit advertising signs or casinos with lots of flashing lights. Australian cities and towns are rarely located on hilly or mountainous terrain so that their high features tend to be high buildings, bridges and towers. Many unimaginative attempts have been made in the past to illuminate these structures and the results could generally be described as aesthetically mediocre. In Melbourne, comparison of the former upwardly aimed floodlights at the Arts Centre spire with the present scheme of spatial, temporal and colour modulation of the lighting does show what is possible while contributing less to light pollution. (This is not necessarily an endorsement of the display or the prospect of reproducing it on other buildings.) Unfortunately, light pollution in Melbourne’s inner western suburbs was approximately doubled when the Western Link of the City Link tollway was completed in 1999. Many hundreds of upwardly directed floodlights are used for decorative lighting and advertising signs. The environmental impact study for the tollway did not consider light pollution or light trespass. Investigations are continuing at the time of writing to ascertain the extent to which the spill light may prove to be an aviation and bird hazard. The billboards are at least an order of magnitude brighter than many of the road signs on the tollway: clearly something is wrong here.

City lighting does not have to be intense to make a lasting good impression: indeed, it can be just the opposite. For example, consider how different Australia’s large cities would look with no unshielded high storey internally lit windows or floodlighting of buildings, just the shapes or outlines picked out along the edges by relatively low power lamps or light pipes, preferably with full horizontal cutoff. If the upper parts only of the buildings were lit at the edges, having the buildings themselves blacked out would give an effect like the line simulations of city buildings on computer screens. This ‘tracing’ style has already been used in several large cities overseas on individual buildings, eg in Singapore. Applied to a whole city, this would surely give a city a distinctive if not unique image. Strict controls (but certainly not a ban) on the lighting of advertising signs would be required to preserve the overall effect.

Other exciting prospects can be envisaged for distinctive city lighting, all of them far more energy conscious and much less serious sources of light pollution than with present practice. The opportunity is open for all Australian towns and cities to adopt such schemes. Individual cities could have their own tasteful variations, but the overall style would quickly become an unforgettably beautiful visual signature for the world’s travellers to associate with Australia. Local authorities across the country need to consider how they can just get on with it. The more extensively it is done, the greater the benefits to all concerned.

Environmental matters have already been introduced above in several places.

Recent opinion surveys have indicated pollution in general to be one of the most important problems needing action in the early part of the third millennium. Urban planning in Australia needs to take far more thorough account of the increasing concern of the community for environmental and conservation values. Here some further detail is given to indicate the seriousness of the need to act now about obtrusive lighting in trying to turn some of the problems around. Rural environments need to be considered as well.

The long-established and substantial contribution of amateurs to astronomical knowledge is actually expanding as powerful telescopes and imaging sensors become more affordable for amateurs. But because most amateur astronomers live in cities and towns the trend is slowing as unnatural urban sky glow caused by light pollution drastically reduces the visibility of nearly all celestial objects. Most light pollution is unintentional and can be greatly reduced by simple and inexpensive technical means without reducing the amount of light available for cultural purposes. Intentional light pollution from searchlights and laser beams is antisocial and environmentally stupid. Such sky beams are therefore best dealt with by outright and permanent bans.

As an example of the numbers of people most directly affected by light pollution, Melbourne’s currently severe urban skyglow adversely affects about nine hundred members of the Astronomical Society of Victoria (ASV) who live in and near Melbourne. Tens of thousands of non-members with a casual, short- or long-term interest in astronomy, eg telescope owners, students and teachers, are also affected. Few of any of these observers who are disadvantaged by poor quality outdoor lighting have any ready prospect or desire for frequent time-consuming and expensive travel to the countryside for their observations.

Professional astronomical research at remote inland observatories is also increasingly being affected by light pollution. For example, despite strict controls on outdoor lighting in the surrounding countryside, the night sky background at the site of the well known Palomar Mountain 5-metre (200-inch) telescope in California is now twice as bright as the natural background. This is five times greater than the maximum acceptable level of sky glow from light pollution recommended by the International Astronomical Union. Australia has professional observatory sites supported by the substantial spending of northern hemisphere countries on staff and facilities. Any repeat of the Palomar experience at these observatories would threaten continuation of this support. Light pollution controls do apply to the area surrounding the observatories at Siding Spring in NSW (DEP 1988), but these controls cannot do anything about the light pollution there that has originated far away in Sydney and other cities and towns in NSW.

In the latter part of 1999, a formal complaint about the proposed decorative floodlighting of Sydney’s new Anzac Bridge was issued by the Mt Stromlo and Siding Springs observatories. This adds to many complaints already received by the NSW Road Transport Authority from amateur astronomers in the Sydney metropolitan area, the surrounding countryside and even interstate. The NSW Minister for Transport imposed an 11 pm curfew and a no lighting condition for nights of special astronomical significance. For professional astronomers, that means every moonless clear night! Note that proposals for lighting the Humber Bridge in the UK and the Vincent Thomas Bridge in California have failed on environmental grounds (CfDS15 1999, IDA NL40 1999).

Ontario has declared Canada’s first official star park in 20 km² of scrubland about 250 km northeast of Toronto. This dark-sky preserve is bounded to the north by Lake Muskoka and vacant Crown land. Neighbouring municipalities to the south have agreed to restrict outdoor lighting within at least 8 km (Nickerson 1999). McDonald Park in the Fraser Valley of Abbotsford, British Columbia has subsequently also been declared a dark sky preserve.

Michigan state in the USA has had its Lake Hudson Dark Sky Preserve in operation for several years. It has been so successful that all Michigan recreation areas now have dark sky protection (IDA NL40 1999). Georgia (1996) has also drafted dark-sky preserve legislation. Notable features of this draft are the specification of ‘ten-degree shielded’ luminaires, ie cutoff at 10° below the horizontal, and an upper limit of 2.2 lux for light trespass at the bottom of bedroom windows. Proposals for dark-sky preserves in Australia are testimony to the inadequacy of existing outdoor lighting controls: while it is an excellent idea at present, universal good outdoor lighting practice could possibly make it unnecessary in the longer term.

At least four of Melbourne’s universities conduct astronomical observations and research in the suburbs, the surrounding countryside and at Australia’s professional observatory sites. Despite this, the principal campus of the University of Melbourne has so much notably bad outdoor lighting that it is itself a substantial source of light pollution. Highly desirable improvements would result from following advice on campus lighting given in IDA IS23 (1996), IDA IS27 (1997) and IDA IS31 (1997). Similar action is certainly required at other university campuses and comparable areas within the Melbourne metropolis and in many other places in Australia.

AS 4282 has particular application to lighting that affects astronomical observatories, especially those registered as significant in a list kept for Standards Australia (ASA 1999). Currently there are five registered astronomical observatories in metropolitan Melbourne (none of which is university-owned) and three others close enough to be affected by Melbourne light pollution. Within this total area there are more than a hundred other observatories eligible for registration. The situation is doubtless on a comparable scale in many other cities in Australia. Although not quite clear on the issue, AS 4282 does specify the need for lighting authorities to consult with registered observatory staff when planning installation of lighting that will affect registered observatories. Light pollution is a serious problem for astronomy and is rapidly getting worse. In Australia, there is an urgent need for immediate remedial action such as universal compliance with AS 4282 and like measures. Voluntary compliance has completely failed to date so that local ordinances should specify mandatory application.

Light pollution at observatories can be of concern beyond its effect on scientific research. The Old Melbourne Observatory in the Domain and Sydney Observatory near the southern approaches to the Harbour Bridge are both listed on the Register of the National Estate (AHC 1999) and are thereby subject to the stringent environmental and preservation controls specified in the Australian Heritage Commission Act 1975 (Cwth). The fact that both sites are already exposed to excessive light pollution does not justify allowing it to become worse, but flush-mounted in-ground lamps for architectural lighting have been installed in recent years at both sites. About half of the light emitted by these lamps goes straight up into the sky, clearly contravening the intent of AS 4282. Although the lamps can be turned off during observations, the installations send entirely the wrong message to visitors and passers-by, viz if upwardly directed outdoor floodlighting is ok for observatories it must be acceptable everywhere else. When these lights are on at the observatories concerned, they also contribute to the burgeoning urban light pollution that ultimately affects everyone, including other telescope users and anyone else looking at the sky.

In the case of the Old Melbourne Observatory, the Astronomical Society of Victoria and individuals have protested strongly about the lighting scheme. No satisfactory responses have been received and the obtrusive lighting continues effectively unabated. Again it is clear that voluntary compliance with AS 4282 is not working. Two points emerge: firstly, the need for mandatory compliance, and secondly, an implication of this, viz the necessity this would impose for compliant outdoor lighting to be specified in building permit applications.

The International Astronomical Union (IAU 1997) has resolved that the night sky is the heritage of all humanity and should therefore be preserved untouched and receive no less protection than has been given to the world heritage sites on earth. There is a long way to go on this.

Light trespass by stray and otherwise unwanted illumination across property boundaries can produce adverse effects ranging from sleep disturbance and sleep loss to discomfort glare and disability glare. Apart from being unpleasant, glare at night often leads to increases in mobility hazards (eg tripping, falling) and road traffic hazards. Generally, appropriate attention to the limitation of light pollution and light trespass by suitable design of luminaires and shielding also provides a superior visual environment (IDA IS125 1997).

Many living things are affected by periodicities in natural illumination, especially the daily, lunar and seasonal cycles (Encyclopaedia Britannica 1990). Disruption of these cycles by artificial light is among known adverse effects of artificial light on plants and animals, including insects and birds. Light trespass is a mechanism for these effects to be experienced over areas substantially larger than the area lit for cultural purposes. Some particular aspects are discussed below in sections 6.4 to 6.7.

Known and suspected effects of unwanted artificial light at night in bedrooms are mentioned above in section 4.2. These add to the reasons given in the preceding paragraphs to indicate that pro-active concerted action against light trespass is needed now as a general policy across all Australian states rather than the current situation in which remedial action only takes place, if at all, as a reactive response to specific complaints.

For a decade, powerful spotlamps installed on the top of the building at 101 Collins Street in Melbourne have been sending vast amounts of light into the sky in a crude attempt to project an image of the Southern Cross while helping to blot out the real Southern Cross. All complaints were ignored, although a different antenna lighting arrangement with reduced use of sky beams was being trialed in 1999.

In 1999, mailed protests about the 100 million candela (estimated) beams aimed vertically up to illuminate the twin 140 m decorative towers of the Bolte Bridge (part of Melbourne’s new City Link tollway) and the air above were unanswered by the companies and authorities concerned until adverse publicity forced a public response, and even then it was only a dismissive denial that there was any problem. Many of the casual observers at the Astronomical Society of Victoria public telescope viewing sessions near the Melbourne Zoo have complained about light pollution and light trespass from the tollway lighting. It is known from an informal network of amateur astronomers and environmentalists interested in combating light pollution that similar situations and tactics of denial and nil response are common across the whole of Australia. This collective experience is a clear indication that industry does not self regulate in this area and will only comply with AS 4282 or similar restrictions when legally required to do so.

In other countries, powerful searchlight or laser beams have been used for similar promotional purposes despite known serious eye hazards to the crew of aircraft in the vicinity. The US Federal Aviation Administration has imposed operational limits on some beams and prevented operation of others. In rejecting an appeal by a sky beam operator against a borough council in the UK, a High Court judge ruled in 1996 that a pattern projection (‘the space flower searchlight’ in the case) was an advertisement and therefore subject to the Town and Country Planning (Control of Advertisements) Regulations 1992 (CfDS13 1998, Jewkes 1998). Sky beams have been banned in several other UK locations, and in Augsberg, Germany (CfDS12 1998). Searchlights and laser beams in the sky are banned for commercial advertising in Japan (EAJ 1997), and a regulation effectively bans upward aiming of spotlights and laser beams except for astronomical purposes in northern regions of Chile (NCE 1998, IDA NL41 2000). ‘Sky tracers’ are banned in Belgium (CfDS15 1999).

If existing sky beams are allowed to continue operating in Australian cities and towns it will only be a matter of time before the precedent encourages so many more that police and emergency services helicopters could have difficulty in operating over the CBDs and inner suburbs. Reflections of intense ground lights from main rotor blades are known to cause flicker vertigo in aircrew. Ground light reflections in cockpit transparencies can seriously degrade visibility of other aircraft and obstructions, and readaptation time after flashblinding prolongs the hazard beyond actual peak exposure. In poor visibility conditions, veiling glare from sky beams, whether laser or conventional, can degrade visibility further.

Organised protests and objections in the media have been at least partly successful in other countries in having sky beams turned off or banned. In Melbourne, public reaction to the searchlights at a casino was sufficiently negative for the searchlight usage to be discontinued. Sky beams send entirely the wrong message to residents and visitors about the credibility of Australia’s commitments to energy conservation and greenhouse gas reduction. Given that on the basis of UN data, Australia’s current per capita greenhouse gas production is 25% greater than in the world’s next most prolific producer, USA (Miller 1999), a complete ban on commercial sky beams is environmental commonsense.

Simon and Babcock (1999) identified light pollution as a major and rapidly increasing threat to national parks in the USA. Specific problems include loss of aesthetic values such as the beauty of the night sky, stress on deciduous trees, and disturbance to wildlife. Increasing light pollution is a subtle threat to street trees, nature reserves, parks and gardens in Australian cities and towns.

The issue of adverse effects of continuous light on plants is far from settled. Much of the evidence at present is anecdotal. The first known mention of effects of light pollution on plants, viz on flowering and fruit bearing times, in local laws dates to 1989 (Ayani 1997). The delayed retention and earlier budding of leaves on artificially illuminated deciduous trees appears to be widely reported, and is often readily observable where street lights are close to tree branches. Trees so affected are also subject to increased probability of frost damage to buds and leaves (USDA & BARC 1975). Tree lights also introduce the risk of physical damage by provision of underground power supply, electrical conduit fixing and luminaire attachment. Street trees represent a substantial investment: for instance, the City of Melbourne has over 18 thousand street trees it values in total at $360 million. Even those who value things only in dollars should see the wisdom of protecting the trees against damage arising from floodlighting at night.

Recently, large vertical cylinders containing floodlights behind canted end plate louvres were installed to uplight trees in Adelaide’s ‘green belt’ as part of Adelaide City Council’s ‘City Entrance Uplighting Plan’. Protests by the Astronomical Society of South Australia and the public were sufficient to halt the installation program at least temporarily pending a review (IDA NL37 1999).

The environmentally sound way of the future in Australia is the abandonment of the tree lighting fad: no floodlights, especially upwardly facing arrangements, and no budlights.

The full extent of the adverse effects of light pollution on natural resources is unknown but is certainly significant. Life on Earth evolved with a definite cyclic variation of night sky luminance of about two log₁₀ units governed by lunar phase. Sea creatures in particular often exhibit lunar synchronicity in their life cycles, with knowledge incomplete as to whether the processes are tidal or photometric or both. Already in and near the urban centre of Australia’s large cities, light pollution reduces this light variation in clear skies to less than half a log unit while the minimum absolute level of sky luminance is over two log units higher than occurs naturally. The presence of cloud results in an even greater discrepancy. It would be foolish to discount the possibility that these large changes lead to adverse effects on marine and aquatic life. For example, beach and road lighting in several southern states of the US has led newly hatched sea turtles astray- they head for the lights rather than the ocean and generally do not survive. Many are killed by cars. As several endangered species are affected, stringent lighting ordinances have now been applied in many localities (IDA IS 29 1997). Turtle disorientation by artificial light also occurs in other parts of the world but is not as well documented. Artificial light from torches (flashlights) is known to disrupt the egg laying of several endangered species of turtles in Queensland coastal and island regions (IDA NL36 1998).

As most Australian state capital cities and many other cities and towns are situated close to the sea, urban sky glow illuminates much of Australia’s coastal waters. This unnatural extra light seems likely to have more damaging effects than beneficial. The same applies to inland waterways near populated areas. This is yet another reason why stray artificial illumination needs to be limited to the lowest levels consistent with cultural and economic factors.

Unfortunately, many town and city authorities in Australia continue to live in the past in terms of wanting to use promotional lighting with hardly a care for effective utilisation of the light and minimisation of Australia’s profligate generation of greenhouse gases. Many schemes for changing city rivers from ‘dark barriers’ to ‘ribbons of light’ have already been implemented and others are certainly in the planning stage. The environmental damage associated with such schemes in many cases is exacerbated by the method used to illuminate shrubs and trees along the banks, ie upwardly facing floodlights. In some cases the water itself is floodlit directly. In any case there are usually excessive amounts of spill light and scattered light present at the water surface.

Australian architecture and design schools must bear much of the responsibility for such outcomes of the training they have provided in recent years. The need for increasing attention to environmental issues has been widely evident for many years but these schools in general have been tardy in adapting their course contents accordingly.

Although enough has been presented above already to indicate that the ‘river of light’ type of concept is ecologically, environmentally and visually unsound, additional reasons against such proposals appear in other contexts below.

From Simon and Babcock (1999) and other sources, it is variously known or claimed that light pollution and light trespass can adversely affect animals as well as plants, eg migratory birds navigate erroneously and the activities of nocturnal land mammals are claimed to be disturbed. In Victoria at least, experience in the specific case of upwardly directed floodlighting of trees is that ringtail and brushtail possums both become disoriented by the upwards pointing lights and stare at them with consequent temporary loss of vision. Given the high intensities often used and the known blue light hazard to animal eyes, it is quite possible that permanent photochemical retinal damage also occurs (ie blindness) in dazzled nocturnal tree-dwelling animals. It is also possible that night fliers such as owls and bats are similarly affected. One Melbourne suburban council (Whitehorse) decided in 1999 against uplighting of trees in a park because of possum dazzle and disorientation.

Birds of most species rest during the hours of darkness. It is readily observable both by watching and listening that high levels of artificial ambient light curtail their sleeping time. Changes in sleep-wakefulness patterns have apparently taken place locally in several marine and coastal bird species, given that many can now be seen flying at night above coastal towns and cities. Species so identified include silver gulls and sulphur-crested cockatoos. Silver gulls in particular can often be seen soaring in circles (thermalling) in upwardly directed architectural floodlighting, and it appears that some birds die of exhaustion as a result. In the case of powerful sky beams, thermalling birds add a bird strike hazard to the aircrew dazzle hazard for low overflying aircraft.

Light pollution is known to be a problem for migratory and other bird species. For instance, one of the conclusions that can be drawn from the annotated bibliography of Hebert, Reese and Mark (1995) is that possibly millions of birds are killed and maimed each year at night by collision with illuminated high buildings and towers in the USA and elsewhere as a consequence of disorientation by light. Occasionally the public outcry in Toronto has been so strong in the case of bird kills by particular towers that all of the tower lighting, even including the red anti-collision lights at the top, has been switched off. More recently, the Fatal Light Awareness Program (FLAP) surveys indicate that the total annual bird kill at night from collision with illuminated towers and buildings in North America is about 100 million (Ogden1996). Perhaps 40 million are killed by illuminated towers, and the 230 bird species identified include many of endangered status (Shire, Brown and Winegrad (2000). The brightly lit high buildings and towers in Australia’s bigger CBDs are therefore likely to be a substantial hazard for birds, including migratory species. Now that the risk has been identified it needs to be investigated. Meanwhile there is a prima facie case for at least a substantial reduction in the external artificial luminance of the higher parts of all high city and suburban buildings and other high structures. Illuminated advertising signs must be included in assessing compliance. Tower lighting other than anticollision should be fully shielded. Decorative lighting of towers and high buildings is deprecated.

In California near Los Angeles, the Vincent Thomas Bridge Lighting Committee proposed to celebrate the new millenium with additional upwardly directed floodlighting consuming a million kilowatt hours per annum. Many objections were raised by astronomers, wildlife experts and environmentalists at the California Coastal Commission hearing in November 1999. The Commission rejected the lighting proposal, primarily because of the potential adverse effects on migrating birds (IDA NL40 1999).

Proposed hockey lights near the Melbourne Zoo are mentioned above in section 3.5. An investigation indicated that the ambient artificial illumination was already high enough to confound natural light-mediated annual and monthly body rhythms of the animals. It appears likely that seasonal and lunar natural photoperiods would be completely swamped by the addition of hockey lights. Wildlife in the vicinity would also be at risk.

In the dark natural environment, trees are always seen darker than the sky background, with luminances down to 10^-6 cd/m². In the Zoo, the trees can often be seen brighter than an unclouded sky background and sometimes brighter than an overcast sky background. With the proposed hockey lights in use, the difference in apparent luminance of silhouetted trees in the natural and Zoo cases could be as much as one million times. Nocturnal animals would rarely if ever dark adapt to the maximum extent, unlike the situation in much of their waking hours in natural conditions.

For conservation of natural resources and biodiversity it would appear prudent to curtail light pollution in Australia, beginning now, rather than allowing it to continue increasing virtually uncontrolled as at present and becoming ever more damaging and ever more difficult to reverse.

While most of us might wish for insects in general to go away and leave us alone, their outright destruction would bring devastation to all life on Earth. Biodiversity is a requirement for the survival of our own species. Not only do we have to share the planet with insects, we need to be careful to avoid upsetting evolutionary dynamics and balances. However, the introduction and growth of electrical outdoor lighting in the last 100 years has apparently had a substantial effect on insect populations (IDA IS109 1996). Moth numbers in particular appear to have declined greatly by attraction to artificial lights and consequent death by impact, heating, exhaustion and predation. Other factors such as habitat destruction and population changes in predator insects, spiders, reptiles, fish, birds and mammals confound the issue. The populations of urban pest insect species that fly by day (eg flies) or do not fly at all (eg cockroaches) appear to be favoured by urban outdoor lighting because it is selectively adverse for night flying insects.

Because of their almost monochromatic yellow output and the relatively low sensitivity of insect eyes to the light of LPS lamps, these lamps have less of an effect than other lamp types in attracting and therefore killing night flying insects such as moths. This suggests that adverse effects on insect population balance can be reduced by ensuring that outdoor luminaires meet the criteria for high quality lighting, viz avoidance of over-lighting and glare, and reduction of light pollution and energy wastage. Where the poor colour rendering of LPS is tolerable or advantageous, LPS should be the first choice.

In recent years there has been a rapidly accelerating trend for the installation of low-mounted upwardly directed floodlights to illuminate trees and buildings. An example already mentioned, and nationally and internationally notorious among those concerned with the growth of light pollution, is the use of 33 in-ground luminaires at the Old Melbourne Observatory to floodlight buildings and trees, contrary to advice and requests for rectification from the ASV. In this and many other installations it is possible for pedestrians to be exposed to the direct beam of individual luminaires. Temporary loss of human visual performance can result, introducing a mobility hazard.

The situation for human eye injury by optical radiation is complex as the human eye is apparently less vulnerable than the animal eyes were in the laboratory experiments mentioned in section 6.6 above. Nevertheless, the intensity, luminance and irradiance (except for erythemal ultraviolet) at eye height from low-mounted floodlights can greatly exceed those of welding processes for which the relevant Australian Standard prescribes dark absorbing filters for safe occupational exposure, and screens or booths for the eye protection of passers-by. Most people react to accidental intense exposure by looking away or rapid lid closure or both but drug or alcohol impairment, a fall, seizure, mental disability or combinations of these could retard or prevent these protective reactions. Furthermore, deliberate sun gazing with disastrous results has often been described in the ophthalmic literature so that intentionally lengthened exposure to floodlights of lesser luminance than the sun in ignorance of the danger is also possible. This is yet another reason to deprecate the use of upwardly aimed floodlights, particularly when they are readily accessible to pedestrians. Lighting authorities also have a duty of care in ensuring public safety. It is certainly not necessary to floodlight buildings to assist mobility safety in the vicinity but specious claims that it is necessary are known.

At the Old Melbourne Observatory in 1999, the writer saw children lying prone on the ground with their faces and open eyes fully exposed to the intense beam of an in-ground floodlight. The authorities concerned dismissed the occurrence as a matter for parental control.

Energy conservation has taken on an increased importance with international pressure for developed nations in particular to limit their production of greenhouse gases as a contribution to reducing global warming and climate change. The Commonwealth has set up the Australian Greenhouse Office to encourage and monitor Australia’s compliance with its commitments under the Kyoto Protocol and the Framework Convention on Climate Change. Full compliance will require substantial changes in existing practices, particularly now that Australia’s position is rapidly assuming crisis proportions. Australia is the world’s worst per capita generator of carbon dioxide even without taking into account the current massive scale of land clearing in Queensland (Miller 1999).

Australian state governments have set up statutory bodies such as Energy Efficiency Victoria to indicate their commitment to climate protection. A Victorian Greenhouse Action statement on 11 August 1998 indicated the Government’s desire for all planning within Victoria to take account of the need for highly positive action to conserve energy, by all applicable means. A measure that is both effective and economical is to avoid or limit the energy waste associated with light pollution and light trespass (Hunter and Crawford 1989). The Victorian Government’s own performance of June 1999 in defending the light pollution caused by the 100 million candela sky beam of the Bolte Bridge is, in political terminology, ‘humbug’. The same applies to the NSW Government’s decision to allow brilliant upwardly directed floodlighting of the new Anzac bridge.

The several other Australian Standards that deal with outdoor lighting, including sports lighting, generally range from marginal to quite deficient in reference to the need for stringent control of light pollution and light trespass. They barely mention what is now a greenhouse gas crisis in Australia. For example, in Victoria the increase in electrical power generated since 1990 is about 33%. On a pro-rata basis, this is 7.5 times greater than the 8% maximum growth by 2008 in greenhouse gas emissions over the 1990 value, the international obligation accepted by Australia under the Kyoto protocol. The writer’s analysis of two sets of observations of actual light pollution observed from Melbourne suburbs in that time shows that the amount of light pollution has increased by about 90%. The unnecessary generation of greenhouse gases implied during 2000 is therefore about 20 times as much as the 4.4% pro-rata obligation. To get Melbourne’s outdoor lighting growth back on target by 2008, installation of all new lamps in 2000 and following years needs to be accompanied by decommissioning of at least 21 times as many existing lamps of a given energy consumption!

In NSW, the Sustainable Energy Development Authority has an Energy Smart Homes Program. Energy-efficient outdoor lighting is included. Nearly half of the NSW population and half of the residential housing approvals are covered by the 39 local councils in the scheme at June 1999 (SOLIS 1999b). But this scheme, commendable as far as it goes, does not address the pressing need to reverse the trend of rapid escalation in the amount of outdoor lighting in Australia. All levels of government need to ensure that no new outdoor lighting installations of any sort are permitted unless compensated by removal from service of an installation of equivalent or greater energy consumption.

For outdoor lighting installations that are environmentally undesirable or unacceptable as well as being politically or socially desirable, one method of compromise between cultural and environmental pressures is to allow the installations provided that curfews are applied to operations. AS 4282-1997 encourages the use of curfews by allowing brighter outdoor lighting prior to a declared curfew. Both the default and actual curfew times are fixed in terms of civil clock time and generally do not keep pace with the seasonal variation in the duration of daylight. The onset and cessation of Daylight Saving Time introduce step changes against the seasonal phase. Given that the adverse effects of light pollution and light trespass are often linked to the degree of supplementation of natural light levels, curfew times should be linked to the time of sunset, or better still to the end of civil twilight. Existing practice of tying curfews to clock time is highly undesirable in terms of distrupting the annual and lunar photoperiods that control the behaviour of many living things.

Actually, the heading is a sardonic joke as Australia lags the real pioneers by at least four decades. Melbournians like to mention their city’s international designation as the ‘world’s most livable city’ but it, like all other Australian cities, it is far behind many other places in the application of world’s best urban lighting practice, and recently took a quantum leap even further behind with its new tollway lighting. Flagstaff was the first city in Arizona, and possibly the world, to adopt an outdoor lighting ordinance, in 1958. By 1990 another 33 cities (including Tucson) and all counties in Arizona had followed suit (IDA IS5 1996, IDA IS55 1996, IDA IS91 1994, IDA IS94 1994). Although much of the credit for this must go to Tucson resident Dr David Crawford, founder of the International Dark-Sky Association, success has also been dependent on continuing demonstrable economic and social benefits of improved outdoor lighting. The benefits have to be quite substantial to overcome apathy, ignorance and resistance to change.

Many small communities on the coasts of Florida and South Carolina have introduced extremely strict controls on obtrusive lighting since 1980 or earlier (IDA IS116 1997, IDA IS29 1997). San Diego in California has had a light pollution law in force since 1985 (IDA IS37 1997). In 1991 the State of Maine passed an act to improve outdoor lighting (IDA IS46 1998). Eatontown New Jersey enacted an outdoor lighting ordinance in 1993 (IDA IS92 1997, IDA IS93 1999). New Jersey has adopted obtrusive lighting controls (recommendation described in IDA IS121 1997) and similar action is in hand in Wyoming (IDA NL36 1998) and Rhode Island (RIHR 2000). Texas (year not available) has adopted State Law HB916, which prohibits the use of state funding to install or operate light polluting luminaires. New Mexico has passed its Night Sky Protection Act (IDA NL40 1999, NM 2000) and NY State representatives have introduced a Light Pollution Control Bill, A6357 (IDA NL41 2000). Many individual cities in the US have passed light pollution ordinances: see Coles and Cady (1999) for a typical example in Idaho. Other measures to combat light pollution extend through most of the USA, as indicated by the fact that only 9 of 50 states surveyed were not using at least some full cutoff luminaires on roads and highways (IDA IS117 1997). However, many full cutoff highway lights (‘shoebox’ type) are already installed on freeways in one of these states, California, and a full cutoff type is specified for all new installations on state highways there (Ca 2000).

Information to hand about light pollution laws in other countries is patchy. Golden Bay County in New Zealand has had stringent controls in place for 10 years to control light pollution and light trespass (IDA IS36 1997, Tasman District Council 1989). Bisei Town in Japan likewise enacted a stringent light pollution control law in 1989 (Ayani 1997). A survey by the Council for the Protection of Rural England in March 1996 indicated that 22 local authorities had light pollution policies in place (Jewkes 1998). Other UK regional controls on obtrusive lighting are reported CfDS13 (1998) and CfDS14 & 15 (1999).

It is understood that substantial parts of continental Europe have full cutoff outdoor lighting in place but documentation to hand on this is sparse. Augsberg in Germany was the first European city to declare itself ‘against light pollution’ (CfDS12 1998), with 2005 as the target date for all outdoor lighting to be modified to ‘sky-friendly’. In France, L’Association Nationale pour la Protection du Ciel Nocturne is having a substantial influence on curbing light pollution, while in Italy, the new Ciel Buio (Dark Sky) organisation quickly collected 27 000 signatures in a petition for an outdoor lighting code in the Lombardy region (IDA NL40 1999). Commercial outdoor lighting is regulated in Belgium (CfDS15 1999).

The situation from one Australian city to the next is rather uneven. Brisbane City Council has certainly made progress with its obtrusive lighting control policy. Unevenness also applies within individual towns and cities: for example, Melbourne is now one of Australia’s worst per capita light polluters despite early efforts in obtrusive lighting control by the former Box Hill and Nunawading City Councils. However, the Melbourne City Council is actively developing an ‘ambient lighting’ code. Obtrusive lighting controls have been in place for many years near the Mt Stromlo Observatory in the Australian Capital Territory (ACT) and a more recent plan to extend controls to all of Canberra and the remainder of the ACT is well advanced (ACT 1997). In central NSW, outdoor lighting controls have applied for many years to a large area surrounding the Siding Springs observatory site (DEP 1988), and the more recent Energy Smart houses program has had a useful statewide impact.

The Sydney Harbour and Parramatta River lighting controls mentioned in 5.1 above apply to areas covered by 14 local councils. Furthermore the South Sydney Council is introducing a landscape development code that includes restrictions on light spill and the specific requirement for compliance with AS 4282 (SOLIS 1999a). Sydney City Council has introduced a Decorative Lighting Masterplan for the CBD, with building floodlighting specified as downwardly directed. This plan includes special occasion lighting. There have been several recent cases of buildings and new billboards being uplit but protests have led to downlighting conversion (SOLIS 1999b). However, overall light pollution in metropolitan Sydney remains excessive by any measure.

The State Rail Authority of NSW recently ordered over 5000 full cutoff luminaires for metropolitan and country railway stations. These lamps comply with the newly revised Part 2 of AS/NZS 1158 and also with AS 4282. Their 150 W metal halide lamps provide suitable illumination for video surveillance. Installation is expected to solve a glare problem for train drivers (SOLIS 1999a). Extensive use of full cutoff luminaires with high pressure sodium lamps has also been made by the Melbourne metropolitan rail system, but again lamps of excessive power rating have been fitted.

In controlling light pollution and light trespass, local government authorities would therefore be on a path already pioneered long ago overseas and more recently elsewhere in Australia. There is little technical risk in adopting such well established procedures. However a key point of this document is that while there are good environmental reasons for Australian cities and towns to follow this path, it is possible by the same applications of technology to derive additional great benefit for residents and visitors alike in visual comfort, amenity and signature, as suggested in section 5.3. The cost differential over existing arrangements appears unlikely to be large either way. Certainly the International Dark-Sky Association claims that control of light pollution can be accompanied by substantial savings.

Given that Australia has international obligations to meet on limiting its greenhouse gas emissions and the fact that the larger cities at least are already subject to the ill effects of perpetual artificial twilight all night, the amount of electrical energy used for outdoor lighting needs not just to be capped at its present level but reduced by government action.

Nothing in any new Australian lighting codes should inhibit the introduction of new forms of artificial lighting provided that these forms meet the ergonomic and economic requirements of users and owners, and that they do not conflict with the visual amenity and environmental aims and provisions. Present inventories of luminaire and lamp types need to be examined for at least two reasons: (i) getting rid of the environmentally bad components, eg clear or translucent (‘opal’) globe luminaires that radiate more than half of the total light output upwards, and mercury vapour lamps, and (ii) a smaller inventory will make it somewhat easier to add new developments in artificial lighting (eg solid-state lighting) if trials indicate this to be desirable.

Many new ways of generating light have been invented and developed in the 1990s, for example blue and white light-emitting diodes, polymer light sources and the rather esoteric generation of light with electron beams and diffraction gratings. Commercial lighting application of some of these is already happening. Regardless of the form of such developments, the principles of high quality outdoor lighting practice should remain applicable, viz provide the right amount and quality of light where it is needed and minimise light spill and glare in other directions.

Road lighting is major source of obtrusive light. Some of the light that falls on the road and on traffic on the road is partly absorbed. Another part of this incident light is partly reflected and may contribute to light pollution and light trespass. Excluding light spill, the incident light generally has cultural value and deliberate containment of the reflected component is neither desirable nor practicable in most circumstances. Rather it is the light spill outside the road and adjacent footpaths and upwards that is usually targeted by obtrusive lighting objectors.

Existing road lighting varies widely in the amount of light spill produced and its angular distribution. ‘Cutoff’ luminaires for road lighting (meaning ‘full cutoff’, ie no light to be emitted above the horizontal) have become more widely used in recent years. Roads in Illinois are in the process of a complete changeover to full cutoff lighting (NELPAG 1997). Connecticut (date not known) law specifies full coutoff luminaires for state-funded highways. In this and many other light pollution ordinances in force in the USA, none of the light emitting part of a road lighting luminaire is permitted to be lower than the horizontal edge of the cutoff shield. However, cutoff luminaire specifications often allow a small percentage of the light to be emitted above the horizontal, presumably to take account of luminaire orientation misalignment, diffraction, and manufacturing and measurement tolerances.

Note that in some circumstances, luminaire cutoff shielding can usefully restrict direct light emission to angles well below the horizontal. The exact value is a compromise between glare reduction and extent and uniformity of direct illumination.

Until recently in Australia, there was virtually no control on the amount of light spilled by luminaires intended for installation on minor streets, parks, plazas etc. Upper limits have now been set for the Upward Waste Light Ratio in new and revised parts of AS/NZS 1158, ranging from 6% to 40%. Although these limits are still arguably much too large, the new specifications are a substantial improvement over the previous situation in which there were often no limits at all. For this reason, many existing luminaires do not comply with the new requirements and will need to be replaced rather than maintained in due course. The UWLR allowed for luminaires intended for use on major traffic routes is unchanged at 6% but again there are pressing environmental reasons and good human factors reasons (eg reduced visual discomfort from glare) to support a reduction in this amount of waste also.

The ‘cobra head’ luminaire is widely used on roads in the USA, Australia and elsewhere. The original lens projects well below the opaque upper shell so that the UWLR can be substantial. To convert the original fitting to a nominal cutoff type, either a supplementary metal shield can be fitted or a flat lens can be installed. (RASC (1999) has pictures.) Many US states are now using the flat-lens modification. Another common cutoff luminaire type is popularly called the ‘shoe box’, and is increasingly being used for non-road applications such as sports lighting as well as for road lighting.

In the case of CBDs or anywhere else of sufficient importance, there is no need for road lighting to be constrained by the limit performance specified in the Australian Standard: better performance is legally acceptable and may be readily justifiable. Below-horizontal cutoffs are certainly feasible, and can allow observation from a closer horizontal distance before the lamp is visible directly, ie reduced glare. Any consequent cost differential arises from the need for a closer spacing of lamps or higher mounting of more powerful lamps to achieve a desired degree of illuminance and uniformity of illuminance along the road (IDA IS78 1998). Often this will translate to a need for more poles or higher poles, a disadvantage to be balanced against the benefits of better lighting. In fact seeing can be improved so much by the elimination of glare that reduced illumination levels can be quite feasible.

The economic benefit of inventory reduction of road and public lighting lamps is important but operating costs and environmental consequences of factors such as spectral output must also be taken into account. Mercury vapour lamps are environmentally unsound for reasons including prolific emission of near ultraviolet radiation. They should be replaced by other types at their end of life, preferably those without a mercury content because of the associated toxic waste problem.

Although LPS lamps are generally falling out of favour for road lighting in the USA (IDA IS117 1997), their widespread usage has proved particularly economical in San Diego, Long Beach and San Jose in California (IDA IS13 1996). Elsewhere, they continue to be used for public lighting in specific locations such as parking lots where colour rendition is not important (IDA IS12 1996). They are also superior when efficient spectral line rejection by filters and a high ratio of visible to invisible optical radiation output are required, as for locations near observatories (IDA IS94 1994) and wildlife reserves.

Although LPS is usually not the first choice for road and public lighting in CBDs and shopping centres it is specified, appropriately, by AS 4282 for locations near observatories. As mentioned above, both Sydney and Melbourne have heritage observatories close to the respective CBDs. Full cutoff LPS road lighting should be used in the vicinity. Plants and animals at botanical gardens would also benefit from preferential use of LPS for pathway and road lighting nearby. A cultural shift away from overbright lighting is an environmental necessity. Better (ie reduced glare) lighting at and near sensitive sites, even if they are close to shopping centres, is a good way to begin this cultural shift. But constant vigilance is required to prevent misguided ‘improvement’ of road and other lighting. As an example, the overbright and light polluting HPS road lamp closest to the Old Melbourne Observatory was recently replaced by an even brighter and bluer metal halide lamp. Although this new fitting approximates full horizontal cutoff, its height and location provides greatly undesirable increased direct illumination of the nearest domes and the surrounding grassed areas. After mistakes such as this have reached practical accomplishment they become notoriously difficult to have rectified. Prevention is better than cure.

Many Australian cities and towns have wildlife parks or zoos. Environmentally unsound lighting at and near these places should be replaced with minimal LPS fittings. Light trespass over the property boundaries or walls should be rigorously controlled to minimise animal distress. While zoos, parks and gardens in general should be unlit, any path lighting required for safe mobility on foot should also be with fully shielded LPS downlighting. LPS is less attractive to moths than other lamp types of equal luminance (IDA IS109 1996) and similarly, LPS can be expected to be less of a problem for nocturnal animals having a visual spectral response like that of rod vision in humans (IDA IS136 1998). Such animals are relatively less sensitive than are photopically adapted humans to LPS light.

Not the least value of LPS for ‘security’ lighting is that its poor colour rendition is thought to discourage graffiti vandals. LPS is to be used where appropriate in a subsidised scheme to improve the view from trains in NSW. Guidance on shielding and motion detection switching is to follow AS 4282. Mercury vapour lamps will not be permitted (SOLIS 1998a).

Existing practice in Australian and overseas cities is for some buildings to carry advertising signs such as illuminated billboards and company logos. There is a tendency for such signs to be brilliantly lit to attract attention and to send the message that the company concerned is so rich and successful that it can afford the large power consumption costs of such signs. The same applies to building floodlighting considered as an advertisement. Unfortunately, large and brilliantly lit signs and floodlit buildings are major sources of light pollution, light trespass, glare and excessive production of greenhouse gases. The problem is growing because bigger and brighter are measures of advertising effectiveness. Parts of the advertising industry have publicly expressed a disregard for and opposition to socially reasonable and responsible upper limits to the luminances, total light flux and energy used. ‘Ratcheting’ between competing companies takes place, as with illumination races between rival petrol filling stations or convenience stores (IDA IS145 1998). Industry self-regulation has obviously failed to date in these areas so that mandatory controls are required.

The absence of controls on the amount of light emitted by signs above the horizontal encourages the use of internally illuminated signs and upwardly directed floodlighting (IDA IS35 1997), both of which tend to be particularly prolific sources of upwardly directed waste light. Although AS 4282 includes limited constraints on advertising signs, it is clear that more direct constraints are sorely needed. While these remain missing from AS 4282, regional lighting codes need to back up mandatory application of AS 4282 with further limits on light pollution, light trespass and glare characteristics of outdoor advertising consistent with overall good outdoor lighting practice. For instance, where an advertising sign or floodlit building is visible to a driver, it would seem reasonable that its luminance should not exceed that of any road sign in the vicinity, given that road sign visibility is important for road safety and that road sign luminances are set at what is considered to give adequate visibility. If such additional constraints prove effective in practice, this could lead to their incorporation into AS 4282 in due course.

Upwardly emitted artificial light from signs is generally worse than useless. High mounted downlighting is a practical proposition (IDA IS35 1997). For internally illuminated signs, upwardly emitted waste light could be limited by horizontal louvres as in venetian blind arrangements or the same thing in miniature incorporated into the light control plastic sheets that are commercially available. A better arrangement would be to redirect the waste light so that it adds to the useful light heading in the direction of people able to see it. In this way the sign luminance in the direction of viewers can be maintained for a reduced input power, an environmentally useful result. Sign makers could be encouraged to achieve this by a specified electrical power limit per square metre of sign. The limit could be set sufficiently low to prevent even a highly efficient sign from disturbing the visual ease of those seeing it at any likely distance. Luminance limits would still be required to cover the case of electrically efficient solid-state light sources. Overly bright billboards can create the deep shadows feared as hiding places for criminals waiting to make a surprise attack.

The need for mandatory control is reinforced by the results of a recent email survey by the Royal Automobile Club of Victoria. The responses have led the RACV to formulate proposals for controlling the form and placement of roadside billboards affecting road safety and scenic and historic aspects (Lay 2000).

Lighting curfews make good environmental sense for items such as decorative and billboard lighting. An even better alternative that has recently become popular in some parts of the USA is to require billboard lighting and shop or office signs and lighting to be switched off outside the times that the advertised company or shop has its doors open to the public. Such requirements reinforce the need for minimal interference by decorative and advertising lighting with the illuminated properties of public areas- there can be little or no justification for the presence of uneven lighting and deep shadows caused by a nearby sign or floodlight during its operating times.

Current practice relating to outdoor advertising signs in the suburbs tends to environmentally poor and visually obtrusive. The reality in CBDs of large Australian cities is worse, in that light pollution originating from higher positions tends to be more efficiently coupled to the atmosphere than it is for similar sources at heights lower than the prevailing height of buildings in the immediate vicinity. Freer from obstruction by terrain and the built environment, light emitted below the horizontal from high sources can generally travel further through the air than light from similar sources at lower heights, thereby increasing the light pollution potential of higher sources. Light emitted horizontally or slightly upwards from high unobstructed sources can travel in many directions for distances of as much as hundreds of kilometres before the total flux is attenuated appreciably by atmospheric absorption and scattering. Even though spread out at such distances, the light may still illuminate the atmosphere enough to hamper astronomers working at and near the light-gathering limits of ground-based telescopes. The effects are bolstered by the urban sky glow ‘dome’ itself acting as a powerful extended and elevated light source causing further artificial sky glow at distances of well over a hundred kilometres.

High-mounted advertising signs are the light pollution sources of most immediate concern here because they are usually over-lit, ie they are far brighter than the surrounds. However, they are not the only possible high and therefore largely unobstructed sources of light pollution and related evils. Building floodlighting is generally of lower luminance than advertising signs but the total area so lit is usually larger. The total radiated light flux is the product of luminance and area, so that floodlit walls and similar surfaces can also be a significant source of light pollution even when downlit. To this must also be added the contribution of internal light escaping from building windows. All three types of sources need to be controlled to achieve the environmental and visual ease goals proposed. For all three, height increases the importance that should be attached to limiting the upwelling and any unwanted or unusable downwelling light flux they produce. Brightly lit penthouses without curtains or blinds in use to limit light emission attract attention as needing obtrusive lighting control.

Height also works to favour the unobstructed transmission of light in light trespass. Policies of encouraging increased population density in urban areas by approvals of ever-higher residential building developments are unwittingly exposing more people to excessive light trespass. The mitigation of light trespass by shrubs and trees in low rise housing areas becomes increasingly unavailable with higher buildings.

The practice of leaving lights on in empty offices after hours is actually still being promoted by some state governments, contrary to simultaneous claims about commitment to tackling the greenhouse gas problem. Such policies are relics of the past and should be publicly renounced. Lighting genuinely required for after hours work and cleaning naturally remains acceptable but curtains and blinds should be drawn to prevent the undesirable emission of light. (First mention of this requirement in local laws is at least as early as 1989 (Ayani 1997).) Fines for offending companies could be introduced after a period of voluntary compliance. Insofar as indoor safety/security lighting might be required, quite a small amount of glare-free light can be adequate.

In the case of city residences some voluntary improvement might be gained by suitable advice to occupants about making consistent use of blinds at night. Currently it is not universal practice for all external windows to be fitted with blinds, so this also needs to change, preferably at the building plans examination stage. To the extent that blinds are present and used, blackout blinds or near equivalents would be somewhat more effective and building plans could usefully specify these. Room presence sensors to switch off the lights in unoccupied rooms could help to minimise both energy wastage and light able to escape. Tinted window glass is not an adequate alternative as it allows no effective reduction in energy wastage and only a small reduction in light pollution. It also impairs the external view out at night. Open louvres and shade-cloth drapes have somewhat comparable effects. None of these measures have a large effect individually but together they may be sufficiently useful to justify some promotion.

Dealing with specific neighbourhood obtrusive lighting issues is currently the province of local government. However, in Australia generally there appears to be inadequate coordination from one municipality to the next on the level of compliance and the standards used. Light pollution and light trespass from road and other public lighting can also arise as consequences of existing installations to the now superseded AS 1158-1986 which was inadequate for controlling waste and spill light. Definite limits on allowable spill in the current version of AS/NZS 1158 address the problem but certainly do not fully solve it. AS 4282 appears to have some overlap of application and inconsistencies of specification by comparison with AS/NZS 1158. Part of the intention of AS 4282 is to limit urban sky glow but it does not specify numerical limits at all for the proportion of upwardly directed waste light, unlike AS/NZS 1158. This adds to the difficulty of ensuring consistent approaches within and between municipalities. Until AS 4282 is improved by the addition of numerical constraints on obtrusive light emissions, local authorities will continue to be faced with making ad hoc judgements of what is acceptable and not acceptable. As an interim measure, it is recommended that all installations covered by AS 4282 should comply with a 6% maximum UWLR. Although zero would be a more desirable target it would create insuperable practical difficulties that would tend to discredit the standard. The 6% limit provides consistency with the lowest UWLR limit specified in AS/NZS 1158. In due course it might prove possible to refine the 6% limit in line with achieved practice, hopefully in the direction of greater stringency. (Note that since October 1999 Chile has had an enforceable standard that effectively limits UWLRs to 5% for commercial advertising and 1.8% or 0.8% for street lighting during curfew hours (NCE 1998, IDA NL41 2000).)

The authority for road lighting in Victoria is VicRoads, which also deals with traffic safety issues of glare from other lighting such as sports lighting. At present, the charter of the Environment Protection Authority in Victoria does not include light pollution and light trespass. The Department of Natural Resources and Environment clearly has responsibilities related to obtrusive lighting as it affects environmental protection and conservation. Other departments cover tourism and recreation including sport, areas either affected by or generating obtrusive lighting. For Energy Efficiency Victoria, light pollution and light trespass can indicate avoidable energy wastage and unnecessary greenhouse gas emission. The Department of Infrastructure has responsibility for urban planning and accordingly also needs to consider minimisation of obtrusive lighting. To date, it has not been conspicuous in doing this.

It therefore appears that no single body has an overall coordinating role in obtrusive lighting control in Victoria. It seems that the situation in other Australian states is not much different, although the ACT does appear to be further advanced. One of several possible ways of improving the practical situation is through the local government bodies of the respective state capital cities. By developing a sufficiently comprehensive outdoor lighting strategy along the lines suggested in this document, these bodies would appear set to assume a guiding role on obtrusive lighting control for suburban councils to follow. Presumably this could or would also extend in due course to local councils throughout the rest of the state. State government planning authorities could certainly assist this process. To avoid later embarrassment, the lead councils need to take full account of environmental and conservation issues and trends in their respective outdoor lighting strategies.

At least some state capital cities are already well into formulation of practical outdoor lighting strategies and plans based on existing practices together with improvements thought desirable. Objectionable features in some of the resulting documents have spurred the national development of informal e-mail networks of individuals and environmental groups concerned with outdoor lighting. It is clear that the most contentious areas relate to decorative, architectural and advertising lighting. It is often the case that otherwise commonsense and desirable arrangements include aspects that are contrary to widely observed trends in city lighting being forced by increasing environmental and safety concerns in other developed countries. The point is that world’s best lighting practice strategies cannot be assembled in ignorance of knowledge and understanding of environmentally driven technical and legal limitations and constraints. In the absence of an adequate outdoor lighting code, for example it is conceivable that operation of a newly developed illuminated display could trigger photosensitive behavioural reactions in some bystanders, dazzle or injure possums from a nearby park, cause traffic accidents or lead to criticism about unnecessary generation of greenhouse gases.

Therefore a key conclusion of this report is that an environmentally based comprehensive model lighting code for states, districts or municipalities should be generated as an early step in improving Australia’s outdoor lighting. This is not quite as large a task as might appear to be the case. The references at section 10 below include the full text of lighting codes adopted by various US states, cities, towns and counties, the northern part of Chile, one New Zealand county and one Japanese city. Most of them have common definitions and broadly similar technical requirements. A synthesis of these with due allowance for differences such as the role of Australian Standards and Australian laws should be possible with reasonable effort. Relevant codes and recommendations are given in IDA IS36 (1997), IDA IS37 (1997), IDA IS46 (1998), IDA IS55 (1996), IDA IS77 (1998), IDA IS91 (1994), IDA IS92 (1997), IDA IS93 (1999), IDA IS94 (1994), IDA IS121 (1997), IESNA (1999) and NCE (1998). Due account should also be taken of the relevant views and recommendations of appropriate Australian professional bodies, particularly the IESANZ. Perhaps the lead in this process should be taken by Standards Australia as it already issues codes of practice in other areas. Any such outdoor lighting code should draw on and extend the concepts in AS 4282-1997. Controls on the luminance of outdoor advertising signs and structures must be included if AS 4282 itself has not had these included by then. These would be in addition to the limits for UWLR mentioned above.

With a comprehensive and informative outdoor lighting code for guidance, local government and private enterprise lighting designers and innovators could proceed with decorative and functional applications that would be far less likely to involve them in legal actions or at the focus of an environmental protest. The value of such codes has been amply demonstrated by their decades of existence elsewhere and the growing extent of pressure for their adoption both nationally and internationally.

World’s best outdoor lighting practice allows comfortable and safe vision while conserving energy and minimising environmental ill effects. Overall, Australia’s cities, towns and rural areas lag badly behind this practice at present. Turning this around would assist development and prosperity and epitomise advanced technology, efficiency, environmental care, comfort and elegance. Australia would be better able to attain and maintain a world ranking for tourism, trade and business.

City lighting needs to satisfy the shared and special needs of three main groups: city users, city residents, and tourists/travellers. Town lighting requirements are similar although possibly more determined by residents’ needs. Rural lighting tends to include more specific purpose or specialised functions. Regardless of these differences, outdoor lighting in general should follow established standards of illumination. The single most important improvement that can be made to outdoor lighting is to eliminate glare by appropriate selection and shielding of all light sources. Where economically feasible, attention to improved uniformity of illumination is desirable.

Luminance maxima in the outdoor visual scene at night need to be limited relatively and absolutely, with the upper hemisphere brighter wherever practicable. Verandas and awnings can help in business districts and shopping areas. Good colour rendering and glare and contrast control will also assist persons with subnormal vision. Poor colour rendering and low pressure sodium (LPS) lamps go together. The use of LPS in appropriate circumstances may confer special advantages in terms of graffiti deterrence, economy, reduced greenhouse gas emissions, and minimal interference with astronomical observations.

Intense or continuous lighting does not necessarily assist personal or property security. On a historical basis, urban crime rates have increased together with the increase in urban outdoor lighting. There is no reliable evidence that increased outdoor lighting reduces actual crime rates. Seclusion rather than dim lighting favours crime. Crime is a social problem, not a lighting problem.

Luminaires with full horizontal cutoff to reduce glare are becoming more common world-wide for road, public and sports lighting. In the USA, modified ‘cobra head’ luminaires with a flat lens and ‘shoe box’ luminaires are widely used; both types having a full horizontal cutoff. Existing outdoor lighting along roads approaching most Australian towns, cities and CBDs is excessively glary. AS 4282-1997, Control of the obtrusive effects of outdoor lighting, should be applied to promote visual ease. Elegant minimalist urban outdoor lighting could enhance tourism in Australia.

Unnatural urban sky glow caused by light pollution drastically reduces the visibility of most celestial objects, degrades aesthetic enjoyment and hinders scientific and recreational astronomy. Most of Australia’s population centres are more or less severely affected. The southern Milky Way and Magellanic Clouds are often blotted out. In the worst affected cities, the Southern Cross already appears as just a triangle and the urban areas where this occurs are expanding steadily. Light trespass by unwanted illumination across property boundaries can cause sleep disturbance and sleep loss, introduce pedestrian mobility hazards and contribute to road accidents. Light trespass control should be a general policy rather than a complaint response, pro-active rather than reactive.

Urban light pollution threatens street trees, nature reserves, parks and gardens. Exposing coastal marine areas and waterways to increased illumination would be environmentally irresponsible given that reductions already appear desirable or necessary. Upwardly directed floodlighting of trees disorients and dazzles nocturnal animals such as possums and possibly other species. Exposure to intense floodlighting sources may result in permanent photochemical retinal damage in animals as well as in humans. High illuminated structures disorient and kill or injure migratory birds. Obtrusive lighting adversely affects other birds also, as well as insect populations. Use of full cutoff LPS lamps can help to minimise many of these adverse effects.

Light pollution and light trespass represent unnecessary greenhouse gas production. Empty offices should not remain lit after hours. A complete ban on commercial sky beams is environmental commonsense.

Therefore a key conclusion of this report is that an environmentally based comprehensive model lighting code for states, districts or municipalities should be generated as an early step in improving Australia’s outdoor lighting.

There is a need for more concern and active coordination among authorities in Australia about control of obtrusive lighting. One possibility is for capital city municipal authorities to lead by example. An environmentally based comprehensive model outdoor lighting code for states, districts and municipalities should be developed, possibly by Standards Australia. Such a code should be adopted widely as an early step in the improvement of outdoor lighting. Many examples of codes from other countries are readily available for guidance. An Australian outdoor lighting code would be a desirable accompaniment to AS 4282. Compliance with that standard should be mandatory within municipalities, regions or states so that inclusion of compliant outdoor lighting in development applications would be a necessary condition for issue of building permits. As comparable procedures are well established in many other countries, their application in Australia carries low technical risk. They would help to ensure that all outdoor lighting would be safe and effective, as well as setting in place a path for Australia to achieve some sorely needed improvement in its world standing for good environmental practice. It also needs to be kept in mind that artificial light at night is not as universally benign for humans and other species as was generally assumed in the 20th century.

Australia needs to reduce the amount of electrical energy being used for outdoor lighting. Responsible authorities should ensure that no new outdoor lighting installations should be approved unless compensated by removal from service of another outdoor lighting installation of equivalent or greater energy consumption. When curfews are attached as a condition of use, natural ambient photoperiods should be kept as intact as possible by tying curfews to the end of civil twilight rather than to clock time as at present.

Specific recommendations are that the Commonwealth, States and individual municipalities should:

Mr Geoff Dudley, Director of the Outdoor Lighting Improvement Section of the Astronomical Society of Victoria, drew the writer's attention to some of the issues raised, provided some of the references and made useful comments on a draft of this report. Several other members of the Society contributed in identifying characteristics of specific sources of light pollution and in exploring ways of achieving improvement. Members of the Sydney Outdoor Lighting Improvement Society, the International Dark-Sky Association and other groups for the improvement of outdoor lighting offered encouragement and useful information. It is a pleasure to acknowledge all of this support. The writer alone is responsible for the content of this report.

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