Articles about Light Pollution


AMA adopts community guidance to reduce the harmful human and environmental effects of high intensity street lighting.  Press Release, 14 June 2016, American Medical Association. .

For more information, also see: Stevens RG. Doctors issue warning about LED streetlights.  The Conversation, 21 June 2016 Article: “What Rising Light Pollution Means for Our Health” 17 June 2016

By Richard G. ‘Bugs’ Stevens, University of Connecticut 

Discusses issues including the fact that the most light-polluted country is Singapore, where the entire population lives under skies so bright that the eye cannot fully dark-adapt to night vision.  The increasing illumination of night has converged with our growing understanding of circadian physiology, and how light at night can disrupt that physiology. The suspicion has emerged recently that some serious maladies could result from circadian disruption such as poor sleep, obesity, diabetes, certain cancers and mood disorders. The most potent environmental exposure that can cause circadian disruption is ill-timed electric lighting, particularly at night.

There are also some severe ecological consequences of light pollution that include mortality events on migrating birds and sea mammals.


International Dark Sky Association

Visibility, Environmental, and Astronomical Issues Associated with Blue-Rich White Outdoor Lighting

Missing the Dark: Health Effects of Light Pollution.  Ron Chepesiuk

 Listverse article:



Barry Clark, PhD (Melb)

© Copyright B. A. J. Clark Australia 2016

Part or parts or all of this document may be copied, reproduced, circulated and stored without restriction for non-commercial purposes provided that due attribution is made to the author. All other rights reserved.



Barry Clark, PhD (Melb)

24 January 2016

Light Pollution

Environmental pollution is the human-caused release of a pollutant such as mercury into the environment. Likewise, light pollution is the release of artificial light into the environment, nothing more, nothing less. This definition was internationally agreed in recent years under the auspices of UNESCO. It is precisely quantifiable and removes the confusion that arose when the term was also used indiscriminately to describe the effects of light pollution. However, alternative definitions are still in common use: for example, “the terms ‘light pollution’ and ‘obtrusive light’ are used interchangeably to mean light shining where it is not intended or wanted” despite the inevitable disputes regarding whose judgement of intention, need or degree of unacceptability is to be accepted.

Although artificial light has profoundly benefited civilisation and transformed our quality of life, it can also give rise to adverse effects such as artificial skyglow, glare, obtrusive light nuisance, biological damage and unnecessary generation of greenhouse gases. Artificial light at night is far from being an unmitigated good. This is increasingly being recognised globally.

In July 2013 national lighting restrictions came into force in France. All offices and shops have to switch off internal lights within an hour after the last worker leaves at night and most external lights have be off by 1 am. The idea is to reduce energy use, to improve public health and to reduce adverse ecological effects. Obtrusive light spill at any time of night has been a statutory nuisance in the UK since 2005. Light pollution control measures are also in place on a national basis in Czechia, Slovenia, South Korea and most of Italy and on a regional and local basis in the USA, Canada, Chile and other countries. A Spanish national law applies light pollution control measures to the Canary Islands and extension to the rest of Spain is under active consideration.

For the most part the lighting industry has opposed measures to reduce light pollution. The industry has prospered for centuries by promoting lighting as a means of reducing fear of crime and actual crime at night. There is no doubt that lighting is effective in reducing fear of crime at night but the journal literature is divided on whether there is a positive, zero or negative effect on actual crime at night. Much of the literature claiming a beneficial effect is tainted by lighting industry sponsorship of the research or other influences and the consequent potential for unwitting introduction of bias. An independent 2003 epidemiological study by the writer indicated that actual reported crime increased reliably with lighting, presumably because extra light facilitated more than deterred the commission of crime.

A new epidemiological study has just been published on the effects of street light reductions on road casualties and crime over the last 14 years in 62 local authority regions in England and Wales. Reducing street lighting in various ways, usually motivated by desires to reduce expenditure and greenhouse gas emissions, did not lead to increases in actual crime at night, contrary to expectations stated by the researchers. Likewise, there was no increase in traffic casualties despite contrary indications from the existing literature. Again, much of this existing literature is conflicted by lighting industry sponsorship and influence.

Astronomers and others who appreciate the features and glories of the natural night sky have certainly had a hand in campaigning against wasteful lighting but the benefits to the whole community go well beyond the reduction of artificial skyglow. Reducing the energy required for lighting makes sense. More can be seen with less waste and less energy consumption by using outdoor light fittings (luminaires) that are fully shielded and direct all their available light output down to where it is needed.

Adverse Effects of Exposure to Artificial Light at Night

The rationale for health benefits of the French government’s action is worth explanation. Life on Earth evolved with a daily cycle of sunlight by day and light as much as tens of millions times fainter at night. Most species have biological rhythms synchronised with the daily light-dark cycle they experience and can be affected by alterations to that cycle. Some species are extraordinarily susceptible to such circadian disruption: for example the vertical migration of zooplankton (which are at the beginning of the food chain) at night can be affected by stray light levels that are down in the starlight range.

Eyes in humans and some other species have cone light receptors for sharp colour vision in daylight and rod receptors for greater sensitivity to faint light at night. In 2002, a third kind of receptor was discovered in mammalian eyes. These intrinsically photosensitive retinal ganglion cells (ipRGCs) respond most strongly to deep blue light and produce neural signals that synchronise the body’s internal clocks and control the pineal gland. In the natural darkness of night, the pineal produces the neurohormone melatonin, a powerful antioxidant, suppressor of some cancers and a starting point for the body’s production of other important biochemicals. Interestingly, melatonin production also takes place at night in the case of nocturnal animals (eg owls and cats).

In the evening, ordinary artificial light levels can be sufficient to delay the onset of these processes and bright light at any time of night can stop the processes completely. In the small hours, long exposure to light as dim as moonlight can reduce the production of melatonin in some individuals. However, all sighted persons with a normal sleep-wake cycle are affected in the morning by bright light such as the onset of daylight: if melatonin is still being produced then its production soon stops and alertness increases. Having eyes shut, as in attempted or actual sleep, during light exposure at night reduces its effects, but this does not reduce or undo effects of light exposure at night before the eyes were shut.

The melatonin cycle is one of many biological processes with a period of about 24 hours, the circadian rhythms exhibited by most species. In humans, disrupting circadian rhythms by exposure to artificial light at biologically inappropriate times, as can happen with shift work, travel across time zones (jet lag) and many other modern activities, can have consequences ranging from feeling flat to increasing the risk of developing or aggravating serious illness.

Currently an intensely studied topic in this broad field is the connection between artificial light exposure at night and breast cancer. Compared with sighted women, totally blind women have less than half the incidence of breast cancer. In other words, light exposure at night is a risk factor in more than half of all breast cancer cases. Laboratory work has shown that human breast cancer tumours grow when nourished with blood taken from women during daytime or at night under bright lighting, but shrink when the blood is collected during a dark night and has a high melatonin level. The medical researchers involved stated unequivocally that “women should avoid exposure to bright light at night”.

In follow-up studies it has been found that small breast cancer tumours are common and can exist for a long time in a state of equilibrium in which they grow during the day and shrink back the same amount at night provided that the amount of melatonin in the blood then has not been reduced too much by artificial light exposure at night. Some of these tumours eventually disappear without intervention. In some other instances of quasi-static breast cancer, it appears that even a single exposure to bright enough light at night (eg sports, stage, commercial or industrial lighting) may be sufficient to trigger tumour transition to the more dangerous proliferative state.

Tamoxifen and Doxorubicin are powerful drugs used to treat human breast cancer. Recent laboratory research indicated that when these drugs were used to treat human breast cancer tumours hosted by rats, faint light at night such as the minuscule amount of room light (0.2 lux) leaking into the laboratory via the gap under the door was enough to render Tamoxifen completely ineffective unless circulating melatonin levels were boosted. It has been known for some time that rats and some other mammal species are more sensitive than humans to melatonin suppression by light exposure at night, but direct experiments on humans to quantify tolerable light levels at night during breast cancer treatment would face ethical barriers. Until the matter can be resolved ethically it would appear prudent to limit patient exposure to levels below those known to produce any human physiological responses other than visual, say no more than 0.1 lux. (One lux is about the amount of illumination produced by a household candle at one metre, and 0.1 lux is about the result at a distance of 3.2 m. Moonlight passes through a value of 0.1 lux a few days each side of full moon.)

Given that the action spectrum (effect as a function of wavelength) for melatonin suppression is confined mostly to the blue part of the spectrum, peaking at about 470 nm, as a practical consideration the room light at night could be safer and possibly brighter if its blue component is diminished by appropriate choice of lamp or use of blue-blocking (amber) filtration, mindful of the handicaps that the resulting yellow or amber coloration might introduce for individuals required to make fine judgements of colour, eg industrial colour matchers, and medical staff in detection of conditions such as cyanosis. Local use of white light sources could get around this issue.

Cumulative exposures to artificial light at night including room lighting, indicator bezels, electronic image screens and streetlight spill into bedrooms may take many years or even decades for consequent illnesses to become apparent, if at all. As with lung cancers from smoking or from asbestos exposure, individual latencies and susceptibilities appear to vary widely across the population.

National and global epidemiological studies indicate that incidences of breast and prostate cancer increase reliably with satellite-measured intensities of towns, cities and countries at night. Tests of the methodology included the absence of significant associations between lung or colon cancer incidences and intensities

In 2007, a World Health Organisation group concluded that shift-work that involves circadian disruption by inappropriate exposure to light is probably carcinogenic to humans. A focus of the group since then has been on finding what types of shift work are the most risky.

In June 2009, the American Medical Association unanimously adopted a policy condemning light pollution for reasons including its potential carcinogenicity. In June 2012, the AMA endorsed a report by its Council on Science and Public Health on adverse health effects of nighttime lighting. As well as breast cancer, the report mentions obesity, diabetes, depression and mood disorders, and reproductive problems. Papers based on the report have since been published in peer-reviewed medical journals. Many other journal papers include prostate cancer, heart disease, reduced immune response and dementia as medical conditions for which artificial light exposure at night appears to be a substantial risk factor.

A difficulty facing researchers in this area is the ethical barrier that prevents experimental treatments on humans where there is a likelihood that the treatment will be harmful to the subjects. Experiments on animals are used as alternatives but animal responses are not infallible guides to human responses. A way around this is to look for epidemiological associations between the illnesses and environmental exposures. For instance, a 2014 journal paper presented a highly reliable positive association between obesity and reported amount of exposure to light at night in bedrooms in a sample of over 100 000 women in the UK, even when adjustments were made for potential confounding effects of sleep duration, alcohol intake, physical activity, dietary items and current smoking.

The three categories of bedroom lighting used in the survey analysis were “light enough to read or light enough to see across the room, but not read”; “light enough to see your hand in front of you, but not to see across the room”; and “too dark to see your hand, or you wear a mask.” Trials by the writer (see the Appendix) indicated the illuminance values corresponding to these ranges.

This provides direct evidence about a safe upper limit for total light incident on bedroom windows at night- no more than about 0.1 lux (about equivalent to the light from an ordinary candle at a distance of 3.2 m), a value the writer and others have independently derived previously on the basis of other evidence. Unless all lighting is made effectively blue-free, this finding also torpedoes the current internationally applied standards scheme of having bright lighting zones for city centres and progressively less bright values for inner and outer suburbs, rural areas and environmentally sensitive areas. Maximum values even lower than 0.1 lux may well be required for conservation of biodiversity.

In November 2009, the UK Royal Commission on Environmental Pollution (RCEP) concluded that light pollution, light spill and glare should be reduced greatly and recommended, inter alia, that unless and until supported by further biological studies, replacement streetlights should not use lamps that emit more blue light than the low levels produced by existing sodium lamps (with matching brightness implied). No progress on this topic is mentioned in the UK Government’s 2013 report on implementation of the RCEP findings, so the recommendation presumably still applies. Note that an international working group of experts in Spain in 2007 had already recommended unequivocally that “Lamps that emit more energy in the blue than standard high-pressure sodium lamps should not be installed outdoors”.

Some adverse ecological effects of outdoor lighting have been found to be worse with white LEDs than with high-pressure sodium lamps, regardless of the colour temperature of the LEDs. This is hardly surprising given that the colour temperature of high-pressure sodium lamps is approximately 2000 K., lower than that of most LEDs used for outdoor lighting to date.

The world peak body for vision and illumination is the International Commission on Illumination (CIE). It is a conservative body, largely dominated by representatives from or sponsored by lighting companies. It is responsible for photometric standards including the SI metric unit for quantity of light. In recent years it has been sufficiently concerned by the biological effects of artificial light exposure at night to set up processes to establish an agreed standard action spectrum of light in suppressing the generation of melatonin and disruption of circadian rhythms in humans.

What is Australia Doing About All This?

Several years ago an Australian breast cancer organisation drew attention to its cause by having women congregate to make up an image display on the Melbourne Cricket Ground (MCG) under the usual bright blue-rich sports lighting at night before they became additional spectators at the immediately following major league football match. The organisation ceased doing this for some time after the writer advised it about the associated health risks, but it has since held another event in which women were encouraged to attend a major league football match at the MCG from 6 pm to 11 pm, this time mainly as spectators. But 300 (un)lucky women were selected to run through a paper barrier on the field, increasing their light exposure somewhat. Given that the playing field is lit to 1500 lux or more for the whole five hours and that the spectator area is lit to about 500 lux for the same time while the playing area is being watched, the reduction in overall light exposure by not repeating the former Women on the Field segment is estimated to be minimal. Thus the original mistake of having the event at night was effectively repeated in full despite the rapid increase in knowledge in the meantime about the precise ways in which light exposure at night increases the risks of breast cancer tumours and their proliferation.

On a broader scale across the population, ‘arty’ lighting festivals and 24/7 lifestyle-promotions are proliferating, regardless of the potentially disastrous long-term consequences not only for some attendees but also for local residents when their windows are flooded with even more light than usual at night. Artificial skyglow above our cities continues to double in between one and two decades, which is unsustainable as well as being an increasing threat to the health of humans, pets and wildlife.

The federal government has a national campaign supplying free compact fluorescent lamps (CFLs) to replace incandescent lamps in households and thereby to save energy costs and reduce greenhouse gas emissions. Many of these CFLs emit bluish-white light instead of the warm white that has a lesser risk of adverse health effects. And the brilliant upwardly aimed external blue-rich floodlighting of the parliament building and other Canberra features typifies the present national disregard for the need for Australia to vacate its place at the top of the list of the world’s worst greenhouse gas emitters per capita.

Australian Standards for road, public and other outdoor lighting still rely on the thoroughly discredited claim that lighting deters ‘illegal acts’ (actual crime). One standard promotes replacement of the orange (blue-poor) sodium street lamps typically used on main roads by blue-rich types, contrary to the UK Royal Commission recommendation mentioned above. Another standard exempts all illuminated advertising signs and the brightest sports lighting from compliance with what are already inappropriately lax limits on light spill into residential windows and environmentally sensitive areas.

State governments continue to do their share of damage also. Bridges, buildings and monuments are often floodlit, usually with blue-rich white light aimed above the horizontal. In the last twenty years at least one state premier has encouraged city businesses to keep empty offices lit all night to give an impression (delusion?) of prosperity. Policies to cram more people into existing cities encourage development of high residential towers, which are efficient at spilling internal light out through windows in a way that produces maximal additional skyglow and stray ambient light and increases associated health risks, especially on cloudy nights when more of the upwelling waste light is reflected back towards ground. Currently there appear to be no requirements for such buildings to have, let alone for occupants to use, light-blocking drapes or blinds at night.

Regardless of the 2009 UK Royal Commission recommendation mentioned above, many Australian municipalities are changing over to mercury-based fluorescent ‘low-energy’ streetlights that still have an excessively blue-rich output, often subsidised by state government funding. LEDs as an alternative are typically manufactured to emit an excessive proportion of blue light although it is not difficult for their colour temperature to be lowered in manufacture to a less toxic level of 3000 K or even 2700 K (warm white, as opposed to daylight and cool white with colour temperatures of 4000 K to 6000 K and higher). However the Royal Commission benchmark was the ca 2000 K provided by high-pressure sodium lamps, which have already proved economical in widespread use for road lighting.

Federal and state environmental and health laws invoke the precautionary principle that requires credible threats to be dealt with even if the science is incomplete, but planning appeals tribunals continue to give precedence to the abovementioned Australian Standards in determining how much light is allowed to spill into nearby residences. Limits for colour temperature and blue-light content are not specified by these standards. State environment protection agencies typically leave lighting issues to municipal councils. These generally do not treat the issue seriously enough, possibly because of the absence of coordinating direction at state level. Overall, the precautionary principle appears to be ignored by choice. Councils appear to be falling well short of the duty of care they are required to exercise in terms of protecting residents and visitors from known serious health risks of excessive blue-light exposure at night.

Like other major cities, Melbourne is experiencing sustained growth in residential numbers. Most residents are unaware of the adverse health effects of the typical levels of nighttime illumination at their windows. Some individual measurements made by the writer twelve years ago in the central business district were as much as 8 lux and there have been substantial increases since then in ambient illumination at street level. As with other cities around the world, inner Melbourne has a higher rate of breast cancer than in its surrounding dimmer suburbs, which in turn exceeds that in largely unlit rural locations. But the City of Melbourne outdoor lighting strategy appears to rest on the notion of using ever more artificial light to facilitate a ‘vibrant’ 24/7 commercial centre, and it actively promotes the annual ‘White Night’ event that encourages the population to adopt a life style that flies in the face of the role of circadian rhythms in health and wellbeing.

How Can Individuals Reduce Their Exposure to Damaging Light at Night?

If you are at all concerned about health in the longer term, you should avoid exposure to all indoor and outdoor sports lighting at night, either as a participant or spectator. This applies to males as well as females. A typical suburban sports lighting installation would have provision for between say 200 and 600 lux at the playing area for competition games. Some commercial lighting (eg in shops at large shopping malls or in the CBD) also operates in this range, which is well into daylight levels. At some footpaths in central Melbourne, measured spill illuminances from large intensely lit billboards amounts to as much as 1400 lux.

Bright commercial and indoor lighting with a high proportion of blue light is fine by day, even beneficial, but it should be avoided like the plague at night. Also keep away from brightly lit railway stations, transport terminals and illuminated billboards, most of which have colour temperatures of 4200 K and greater. Use minimal warm-white room light at home, choose smallish television and computer screens, set them at night to low to medium brightness, lower their colour temperature from the default setting of about 6000 K by markedly reducing the blue component and don’t stay up late watching them. Much the same applies to the display screens of other electronic devices such as computers and telephones. (A free app is available that changes the settings automatically at sunset and sunrise every day.) Get rid of indicator lights that stay on in the bedroom at night, especially any blue or blue-white LEDs- or at least cover them with opaque tape, blue-tack or black ink from a marker pen (and check that they do not overheat). Use a red LED torch at night for bathroom visits.

Complain to the local council if streetlights, ‘security’ lights, billboards or outdoor video screens shine into any room, especially if they use blue-white LEDs or mercury-based lamps (which includes all fluorescents and metal halide lamps) that emit strongly in the blue part of the spectrum. (Keep a record of the complaint and the response in case the matter ends up before a tribunal or court.) Where trips and falls are not an issue, avoid the use of outdoor blue-white LED decorative lights, even if powered by solar charged batteries.

Of course, most if not all of these unhealthy lighting problems have arisen because of failure through all levels of government to take sufficient notice of environmental science research and to act responsibly in terms of protecting community health.

Sports Lighting as an Example of Health Risk

The metal-halide lamps almost invariably used for sports lighting emit blue-white light and provide an illuminance of at least 100 lux on suburban sports grounds at training sessions and 200 lux for low-level competition, all the way to 1500 lux and more at major sporting events that may appear on colour television broadcasts. For comparison the slightly redder light of the full moon is never more than 0.27 lux, seldom more than 0.2 lux and much less or zero for about 90% of night time. At some time during late twilight 1 lux is experienced outdoors. Daylight ranges from tens of lux up to many tens of thousands. Behavioural and biochemical effects of light on humans during biological night have been observed with exposures as small as 0.2 lux for several hours, but usually the threshold quantities are about 10 to 100 times higher. The effects are non-linear; small values of illuminance tend to have larger effects than might be expected on a linear (proportional) basis, which is why even small amounts of light spill may be hazardous. Understanding of the effects of chronic small exposures is currently inadequate, but epidemiological studies suggest that the effects tend to be cumulative and thresholds are consequently smaller than for exposures on one or a few days.

Even with the best possible current form of sports lighting luminaires correctly installed to minimise direct light spill at and above the horizontal there will always be appreciable spill at and below the horizontal plane of the emitting faces of the luminaires. Typically the total reflectance of the illuminated playing surface and surrounds is in the order of 20% (a ‘ball park’ estimate, so to speak). The illuminated area can thus be considered as a distributed light source of roughly one-fifth of the total intensity of the sports lighting, radiating more or less uniformly into the upper hemisphere and thereby contributing to urban skyglow, which is increasingly a health risk as it grows.

Some atmospheric conditions such as rain and mist can increase the proportion of indirect spill from sports lighting and other floodlighting. While the peak illuminance of all sources of spill at nearby residential windows at night will be much less than on the playing field, it may well be more than 0.1 lux which is arguably an upper safe limit from the point of view of adverse health effects of exposure to artificial light at night. Bear in mind that the existing ambient stray light may already exceed this limit, and that spill and ambient illuminances are approximately additive. The lowest limit set in Australian Standards for allowable spill at windows or property boundaries is 1 lux, and many times that may be allowed in bright neighbourhoods and city centres. The Standards disregard any other sources of outdoor ambient light in these circumstances despite the fact that the eye-brain system takes account of all light that enters the eye.

Recent research has identified ‘metro nature spaces’ (or ‘green infrastructure’) including parks as places that can generate public health co-benefits. These include services such as air and water purification, stormwater management, carbon sequestration, and reduction of heat island effects, all of which have been assessed for their potential economic values. Psychosocial services such as the cognitive, emotional, and psychological benefits derived from interactions with nature may also be provided and have recently become of interest as economically quantifiable. Adverse effects of light pollution tend to diminish the environmental health of these spaces; in turn, this tends to reduce the economic value of the health and wellbeing effects they produce. Such losses would be in addition to direct effects of light pollution in reducing human health and wellbeing.

Many metro nature spaces in populated areas are organised sports grounds. Other such spaces have organised sports grounds occupying some part of their total area. Increasingly, sports grounds are being provided with sports lighting. Direct and reflected light spill from this lighting always extends into nearby areas. This spill adds to local sources of illumination such as lighting of parkland paths and facilities and nearby street lighting. Overall, outdoor public lighting tends to increase in quantity and extent because it is a relatively inexpensive way for politicians to give an impression that they are doing something for their constituents.

Artificial light exposure at night has a large range of adverse effects on wildlife health as well as on human health. As one example of many, both bats and insects are affected by light at night in ways that change the balance between predators and prey. Some insect species trapped by outdoor lights at night may be easy meals for some species of bats, which would tend to reduce the insect population and increase that of the bats. That in turn might affect populations of other species of insects and bats and affect pollination of some plant species. Other populations might be affected as a result. The net effect is to reduce biodiversity, a bad result for humanity. Both Commonwealth and State have legislation aimed at preventing biodiversity reduction. Furthermore, degraded wildlife health in metro nature spaces diminishes the value of these spaces for human health, a previously unrecognised factor additive to the adverse effects of direct artificial light exposure at night on human health.

For Victorians, sports lighting is like brown coal in terms of the current reliance of the population on it, but powerful cases for the moderation of both already exist and are growing. Individual sports lighting installations by local councils can cost several hundred thousand dollars of ratepayers’ money, and the present long-term consequences for users, spectators and nearby residents might well end up being worse than if the playing field and surrounds were being sprinkled with asbestos instead.

Reduced Energy Street Lighting

Residential street and other public lighting is a major expense for local councils. The predominant type of lamp used for decades has been the mercury vapour type, often with a fluorescent coating for greater efficacy in turning electricity into light. Unfortunately, the output in both cases is blue-rich, markedly different from the much safer blue-poor amber light from high-pressure sodium lamps typically used for main roads. At present, many councils are changing over to lamps such as T5 fluorescent and light-emitting diodes (LEDs), which may reduce capital and operating costs for a given amount of light. Typically at present, both kinds of lamp more or less maintain the pre-existing proportion of blue light in residential environments at night, contrary to the recommendation of the UK Royal Commission mentioned. Worse, in the case of the T5 lamps, the luminaire that holds them still appears to produce excessive glare for drivers and pedestrians and excessive sideways and upwards light spill. There are severe practical difficulties in trying to ameliorate these problems with add-on light shields. It therefore appears that the lamps and luminaires being retrofitted for street and public lighting in most cases at present are unfit for the required purposes.

Other ‘energy-saving’ lamps with much less blue light output are available, such as LEDs with colour temperature well below 3000 K as well as 50-W high-pressure sodium lamps in fully shielded luminaires. An even better lamp in terms of low energy use and almost complete absence of blue light is the low-pressure sodium type; unfortunately these are now seldom used because sections of the lighting and power industries complained unjustifiably for decades about their poor colour rendering. But low pressure sodium lamps continue to prove highly successful in Flagstaff, Arizona and a few other places that have insisted on getting the best overall environmental performance.

Legal and Social Issues about Light Pollution

Residents at home can reduce their exposure to the blue component of light at night by using lower power lamps with lower colour temperatures- 3000 K types are common and 2700 K types are now commercially available. However, urban and suburban dwellers are increasingly being subjected to high outdoor levels of blue-rich ambient light at night as a result of increased public lighting and commercial lighting (including large video screens), most of which is well outside the control of individuals being affected.

In the UK, a resident’s complaint to a local council about obtrusive stray outdoor illumination at home may be prima facie evidence of an offence by the operator of the lights causing the light nuisance. Based on the writer’s knowledge of obtrusive lighting complaints over 25 years by fellow amateur astronomers and others, the situation is quite different in Victoria. Some local councils do take appropriate action to reduce the problem but others tend to ignore, deflect or dismiss reasonable complaints.

Victoria’s Environment Protection Authority long ago refused to deal with light pollution in any way because it was not mentioned in its Charter. Questioned about this many years ago, both the EPA and the responsible Minister said it was not their place to initiate a change in the Charter and advised contact with the other party. This proved to be a classic run-around situation. Ironically, light pollution now appears to be one of the most serious and widespread environmental threats to health.

Given the increasing amount of scientific information that is readily available about health risks of excessive exposure to light at night, there is a prospect that local councils and their lighting contractors could be sued in due course by residents who have contracted a serious medical condition in circumstances where ambient outdoor artificial blue-light levels in residential areas constitute a sufficiently high risk factor. A successful law suit or class action could ‘open the floodgates’, with potentially catastrophic financial consequences for organisations and individuals found liable.

Industry bodies would appear to carry responsibility for the accuracy and completeness of advice to their clients about the adverse as well as beneficial effects of artificial light usage at night. Ignorance and denial about the adverse effects are commonplace both in the industry and in the branches of government that have a duty of care to clients and constituents. Organisations that are supposed to be working towards overcoming illnesses such as cancers for which chronic or intense exposure to light are risk factors should not promote public events involving undue exposure to bright blue-rich artificial light at night.



Notes  The following list of relevant scientific papers and other documents was originally a reference list for citations in the text above, but the citations were removed to render the text more suitable for publication in part or as a whole in newspapers and magazines. The list is only a small sample of the present scientific literature on light pollution and its effects but nevertheless is reasonably representative. The details provide a starting point for persons interested in the background to issues described in the text. In some cases online access to abstracts is free but full-text documents require payment. Alternatively, free full-text access may be available at university and state libraries.

To access documents with DOI (or doi) codes, the URL is followed immediately by the DOI code. Some search engines will respond directly to the DOI code by itself as a search term.


Blask DE, Dauchy RT, Brainard GC, Hanifin JP. (2009) Circadian stage-dependent inhibition of human breast cancer metabolism and growth by the nocturnal melatonin signal: consequences of its disruption by light at night in rats and women. Integrative Cancer Therapies, 8(4): 347–353. doi: 10.1177/1534735409352320. Accessed online 3 May 2015 at

Blask D, Brainard G, Gibbons R, Lockley S, Stevens R and Motta M. (2012) Light pollution: adverse health effects of nighttime lighting. AMA Report 4 of the Council on Science and Public Health (A-12). Chicago, IL: American Medical Association. Accessed online 3 May 2015 at

Bruce-White C, Shardlow M. (2011) A review of the impact of artificial light on invertebrates. ISBN 978-1-904878-99-5. UK, Cambridgeshire: Buglife- The Invertebrate Conservation Trust. Accessed online 8 June 2015 at


Clark BA J. (2002) Outdoor lighting and crime, Part 1: little or no benefit. November 2002. Melbourne, Australia: Astronomical Society of Victoria Inc. Accessed online 3 May 2015 at

Clark BAJ. (2003) Outdoor lighting and crime, Part 2: coupled growth. May 2003.

Melbourne, Australia: Astronomical Society of Victoria Inc. Accessed online 3 May 2015 at

Clark BA J. (2009) A rationale for the mandatory limitation of outdoor lighting. Melbourne, Australia: Astronomical Society of Victoria Inc, November. Accessed online 3 May 2015 at [The Appendix of this document shows how the relative amount of biologically active blue light can be calculated for any light source and its approximate relationship to colour temperature.]

CPRE (2014) Shedding light. A survey of local authority approaches in England. Campaign to Protect Rural England. Accessed online 3 May 2015 at

Dauchy RT, Xiang S, Mao L, Brimer S, Wren MA, Yuan L, Anbalagan M, Hauch A, Frasch T, Rowan BG, Blask DE, Hill SM. (2014) Circadian and melatonin disruption by exposure to light at night drives intrinsic resistance to Tamoxifen therapy in breast cancer. Cancer Research, 74(15): 1-12. Published Online First 25 July 2014; doi: 10.1158/0008-5472.CAN-13-3156. Accessed online 3 May 2015 at

EU (2000) Communication from the Commission on the Precautionary Principle. COM(2000) 1, 2 February 2000. Belgium, Brussels: Commission of the European Communities. Brussels. Accessed online 8 June 2015 at en.pdf

Flagstaff Dark Skies Coalition (2015) To celebrate, promote, and protect the glorious dark skies of Flagstaff and northern Arizona. Accessed online 3 May 2015 at [This is a particularly informative website.]

Flynn-Evans EE, Stevens RG, Tabandeh H, Schernhammer ES, Lockley SW. (2009) Total visual blindness is protective against breast cancer. Cancer Causes and Control, 20(9): 1753–1756. Published online, 1 August 2009. DOI 10.1007/s10552-009-9405-0. Accessed online 3 May 2015 at

Fonken LK, Nelson RJ. (2011) Illuminating the deleterious effects of light at night. Faculty of 1000 Medical Report, 3: 18. [F1000 Med Rep. 2011; 3: 18.] PMCID: PMC3169904. Published online 1 September 2011. DOI: 10.3410/M3-18. Accessed online 3 May 2015 at

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Constructive criticism and advice of new developments would be welcomed by the author of this document:

Dr Barry A. J. Clark

Director, Outdoor Lighting Improvement Section

Astronomical Society of Victoria Inc

[Registered number A0002118S]

Committee Member, Victorian Chapter of the International Dark-Sky Association

Email: bajc (at)