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LIGHT POLLUTION
Questions & Answers

Updated 3rd April 2009

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Light Pollution, Questions and Answers...

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Q. What is light pollution?
A. Simply put, light pollution is light that is allowed to go where it is not wanted. Light pollution is often referred to as "skyglow" and "light trespass". A common misconception and often quoted urban myth is that the only thing that humans have created which is visible from space is the Great Wall of China: It is in fact the light we send upwards from our planet at night!

Satellite images of Earth show a tremendous variety of features, but one might think that images showing parts of Earth during the hours of darkness would be unrecognisable. The sad fact is that they are all too easy to recognise because of the artificial light that is poorly used and allowed to 'leak' upwards. Major cities, towns, motorways, roads and many other man-made features are all clearly visible from space nowadays due to wasted light. And the problem appears to be getting worse. A recent satellite survey revealed that in just seven years (from 1993 to 2000) the levels of light escaping upward have increased by 17% in the UK alone.

BACK TO TOP Q. What causes light pollution? | Q. What does light pollution affect? | Q. Is astronomy alone affected? | Q. Does it affect other living things? | Q. Does it affect the environment? | Q. Do security lights prevent crime? | Q. Does lighting make night safer? | Q. What does light pollution cost? | Q. Can light pollution be controlled? | Q. What about the Clean Neighbourhoods and Environment Act 2005? | Q. Can you make a difference? | Conclusion | About this article | Links, further reading and reference | Light Pollution - Survey Results

Q. What causes light pollution?
A. Any exterior light source that permits light to go upwards or where it is not needed:

Older street lights are a major cause of urban skyglow. In some instances, lighting schemes for streets, precincts and commercial premises are simply 'over the top' and indiscriminate to no overall gain and are simply wasteful. Illuminated signs and buildings contribute further as does uncontrolled and badly designed and installed domestic lighting.

Light polluter

Above is a prime example of 'over the top' lighting. Pretty much all of the criteria listed above applies and worse still most of the light is being cast ABOVE the horizontal. In a twist of irony most of the surrounding pedestrian and street lighting features full cut-off and shades, that is, no light above the horizontal. (Click on the picture to see a larger photo. Use the 'Back' button on your browser to return to this page.)

The recent trend for so-called "security" lighting (for which there is no clear effect on crime) has further accelerated the amount of wasteful and intrusive light.

Light pollution is not just an urban phenomenon. In rural areas too, 500-watt "Rottweiler" lights wink on and off, spreading their emissions for hundreds of metres outside the premises to be lit. Many lighthouses, and they need to be seen from miles away, often use lower wattage lamps than those used in domestic security lights! Yet we light small gardens with lamps brighter than lighthouse. How much money do we waste in this country by using too much light, worse still sending much of that light upwards?

BACK TO TOP Q. What is light pollution? | Q. What does light pollution affect? | Q. Is astronomy alone affected? | Q. Does it affect other living things? | Q. Does it affect the environment? | Q. Do security lights prevent crime? | Q. Does lighting make night safer? | Q. What does light pollution cost? | Q. Can light pollution be controlled? | Q. What about the Clean Neighbourhoods and Environment Act 2005? | Q. Can you make a difference? | Conclusion | About this article | Links, further reading and reference | Light Pollution - Survey Results

Q. What does light pollution affect?
A. Light pollution each and every one of us, not just astronomers. Light pollution is a nuisance, it is wasteful and despoils the night time environment and places an unnecessary strain on the planet's precious natural resources. Light pollution makes the night sky unduly bright and can prevent stars from being seen. Astronomy from an urban site can be made almost impossible by the encroachment of light pollution. The night sky is a precious national and educational resource and is undoubtedly of great special scientific interest.

It is estimated that at least 50% and possibly as much as 90% of the UK population is affected by light pollution - A survey carried out in 1990 by the British Astronomical Association (BAA) found that over 90% of people who look at their night sky in the UK, even on the clearest nights, see far fewer stars than they might have seen a few decades ago.

To truly appreciate the night sky it may be necessary to travel many miles from a built-up area to see a truly dark night sky. Most major astronomical observatories are now located in dark, sparsely populated areas and in some cases have been forced to move to other countries because of increasing light pollution from built-up areas. All this means that many people have difficulty with or are prevented from enjoying one of nature's greatest free spectacles - the sky at night!

BACK TO TOP Q. What is light pollution? | Q. What causes light pollution? | Q. Is astronomy alone affected? | Q. Does it affect other living things? | Q. Does it affect the environment? | Q. Do security lights prevent crime? | Q. Does lighting make night safer? | Q. What does light pollution cost? | Q. Can light pollution be controlled? | Q. What about the Clean Neighbourhoods and Environment Act 2005? | Q. Can you make a difference? | Conclusion | About this article | Links, further reading and reference | Light Pollution - Survey Results

Q. Is astronomy alone affected?
A. No. Excessive or bad lighting affects all living things. All exterior lights, in particular domestic floodlights, are a common source of nuisance if they shine into a neighbouring property. There are also growing medical concerns as to the health effects of too much light at night, after all, humans are not naturally nocturnal creatures - An example would be streetlights illuminating a bedroom and disrupting the occupants sleep. Light pollution affects people and their interests but it also affects animals and on a much broader scale the environment. Therefore, light pollution should be of concern to everyone.

BACK TO TOP Q. What is light pollution? | Q. What causes light pollution? | Q. What does light pollution affect? | Q. Does it affect other living things? | Q. Does it affect the environment? | Q. Do security lights prevent crime? | Q. Does lighting make night safer? | Q. What does light pollution cost? | Q. Can light pollution be controlled? | Q. What about the Clean Neighbourhoods and Environment Act 2005? | Q. Can you make a difference? | Conclusion | About this article | Links, further reading and reference | Light Pollution - Survey Results

Q. Does it affect other living things?
A. Yes. It has been estimated that every night, somewhere in the UK, 10 000 Robins serenade a false dawn caused by artificial light. The number of other songbirds that are affected may be innumerable. The RSPB (Royal Society for the Protection of Birds) suggest that the decline in numbers of many birds in recent decades may be due to the proliferation of night-time lighting. Generally, if you can hear birds singing at night it is because of artificial lighting. Studies of migratory birds have shown that they may be stimulated into premature migration because of artificial lights. Lights can confuse creatures, especially birds, and cause them to blunder into buildings.

Deciduous trees that are subjected to artificial light have been shown to retain their leaves in winter on the side that is lit at night. Moths and other insects appear to be confused by bright exterior lights. Many creatures are nocturnal by nature and excessive night-time lighting will almost certainly affect them in some way. These are just a few examples of how lights can affect living things.

BACK TO TOP Q. What is light pollution? | Q. What causes light pollution? | Q. What does light pollution affect? | Q. Is astronomy alone affected? | Q. Does it affect the environment? | Q. Do security lights prevent crime? | Q. Does lighting make night safer? | Q. What does light pollution cost? | Q. Can light pollution be controlled? | Q. What about the Clean Neighbourhoods and Environment Act 2005? | Q. Can you make a difference? | Conclusion | About this article | Links, further reading and reference | Light Pollution - Survey Results

Q. Does it affect the environment?
A. Yes, wasted light means wasted energy. The British Astronomical Association (BAA) calculated in 1993 that road lights alone squander over 50 million annually. The Campaign for Dark Skies (CfDS) website currently features a counter which calculates in real time how much money is wasted on poor quality streetlights. We could light another British city free of charge with the wasted light escaping from any two British cities. Today, more than ten years after that study, that figure is certainly greater. This is taking into account streetlights only and not other forms of lighting.

Considering streetlights presents us with some staggering figures... The ten largest metropolitan areas in the United States have a estimated 4.4 million streetlights and these consume in the order of 3 billion kilowatt hours of electricity per year. This is estimated to generate some 2.3 million tonnes of carbon dioxide per year. There is little reason to think that the situation the UK is much different - it is estimated that in the UK alone there are some 8 million streetlights! While many of these lights may be necessary, essential even, one has to wonder how many of the rest are not needed and are simply a waste of money. Worse still, how many of these lights are inefficient, or cast unnecessary light upwards - or both.

The paradox is that many modes of manufacture, transport, heating, and illumination are becoming more energy efficient and environmentally friendly. Yet, more and more lights are springing up all over. Not only that but the power of the lights often increases as well - cancelling out almost any advantage of using more efficient lights! Local to me was the scheme to replace existing streetlights with those that feature full cut-off fixtures. A good thing except for the fact that not only were the existing streetlights replaced, more were added as well!

On the other hand there are some counties and cities that are considering dimming their streetlights. In some countries, especially rural areas, streetlights are often turned off after midnight when they are hardly needed anyway. In the UK there are now some stretches of motorway that are floodlit but the lights are turned off after about midnight to save energy. Schemes such as these appear to be catching on in the UK and along with advances in 'intelligent' lighting and other drives to cut costs perhaps we are at a turning point. One can only hope!

About 25% of all global greenhouse gas emission is caused by domestic energy consumption. A study and project in the United States is under way and it has already shown that if "green lighting" was installed in the US, $16 thousand million could be saved every year. This amounts to 12% of all US carbon/sulphur/nitrogen dioxide emissions. On a smaller scale let us take the example of a floodlight. If it is left on all night, a single 500 watt lamp creates 1.25 tonnes of Carbon Dioxide annually at the power station burning fossil fuels to keep it alight. Now multiply that by however many such floodlights you can think of and you'll realise that this is a significant contribution to energy consumption and emissions.

To summarise, a truly staggering amount of energy (and hence money and resources) is wasted annually for want of sensible, well-designed, and properly aimed lighting.

BACK TO TOP Q. What is light pollution? | Q. What causes light pollution? | Q. What does light pollution affect? | Q. Is astronomy alone affected? | Q. Does it affect other living things? | Q. Do security lights prevent crime? | Q. Does lighting make night safer? | Q. What does light pollution cost? | Q. Can light pollution be controlled? | Q. What about the Clean Neighbourhoods and Environment Act 2005? | Q. Can you make a difference? | Conclusion | About this article | Links, further reading and reference | Light Pollution - Survey Results

Q. Do security lights prevent crime?
A. This is one of the the most contentious and emotive aspects of light pollution and is worth exploring in greater detail. But let us be clear on the matter - there is no clear evidence that "security lights" deter criminals. It seems to be perceived wisdom and belief, urban myth even, that a light will deter or prevent a crime. But a majority of studies in the US show no significant link between crime rates and extra lighting. Studies in the UK have had similar results. Let me re-emphasise... There is no independently funded, peer-reviewed, scientific study that shows a clear link between lighting or additional lighting and reduced crime. In other words, lights seem to make no difference to crime levels.

A recent study in the UK of lighting and crime proclaimed that additional street lights caused a large reduction in crime statistics. That was a study of one area of the UK. However, independent analysis of that study's findings found that the data collection and overall analysis was flawed, invalidating the study's conclusions. It is worth noting that the study was in fact funded by a lighting manufacterer, all such UK studies (including those relied upon by the Home Office) are similarly funded.

Most studies of this kind indicate that the fear of crime is reduced but the actual crime rate is not. It is worth noting that over half of all break-ins take place in daylight, don't forget that criminals have to see as well! Several projects and studies in US schools, colleges, and universities have shown that vandalism actually decreases when lights are switched off at night.

Poorly designed and installed lights are ineffective and can be dangerous in some cases. For example, an excessively bright or poorly aimed light may dazzle onlookers who might otherwise see and report a crime in progress. Lighting up a secluded area may act as a courtesy light for a would-be criminal and may even tempt criminals by making the area more visible. For example, a Dorset secondary school was never broken into for about 20 years since its inception, being set back from the road behind trees and unlit. Soon after sodium lights were installed all around the building, it was broken into, not once but several times in the next few years. As if to emphasise how little effect security lighting has, insurance companies offer discounts for high security locks and professionally installed alarms but they don't offer discounts for the installation of so-called security lights.

One of the worst aspects of the recent trend for "security lights" is that many of the fixtures available cannot be aimed downwards satisfactorily (mainly because their PIR sensors are mounted directly beneath the lamp) and that the lamps are far too bright. Typically, these lights have 300 watt or 500 watt lamps fitted as standard. Cheap to buy, but expensive to run, such fixtures almost thumb their nose at the fact that 150 watts is usually more than enough for a typical domestic drive or garden. There is a generally felt belief that "the more light, the better" yet there is no evidence that extra light has any affect on crime levels...

Let me paint a picture for you...
Think of an building that is lit up. The light advertises the building's presence and the light may actually assist a criminal by lighting the way. In this case the light has actually actually helped execute a crime. If a criminal is disturbed by a light coming on it may deter him but the light itself is no physical barrier to prevent a crime. At this point the criminal may retreat since the possibility of being detected is raised. But when a 'security' light comes on, few people will investigate the fact, since they are so often triggered by passing cars, foxes, cats etc.

However, the criminal may already be trespassing and may still proceed with the intended crime irrespective. If the criminal proceeds and is detected he still has to be challenged or the witness report a crime in progress. This assumes that a witness sees a crime in progress in the first place and that they challenge the criminal. Even if an onlooker sees a crime, will they bother to report it?

Even if the criminal is spotted, even if the crime is reported and someone intervenes, it may still be too late to prevent the crime from taking place. An act of vandalism, criminal damage, assault, burglary, theft, or whatever can take just seconds. And the lights will have made no difference. If only it were as simple as 'light comes on, criminal goes away'! Think about it, so many things have to go exactly to plan if a light is to have any role to play in preventing a crime. Perhaps this is why lighting appears to have no effect on crime?

As mentioned further up this page, a single 500 watt lamp left on all night creates 1.25 tonnes of Carbon Dioxide annually at the power station burning fossil fuels to keep it alight. If, for example, the cost of the electricity is just two pence per kilowatt hour, and the light is lit, on average, for 8 hours a day, all year, a 500 watt lamp costs nearly 30 per year to light.

BACK TO TOP Q. What is light pollution? | Q. What causes light pollution? | Q. What does light pollution affect? | Q. Is astronomy alone affected? | Q. Does it affect other living things? | Q. Does it affect the environment? | Q. Does lighting make night safer? | Q. What does light pollution cost? | Q. Can light pollution be controlled? | Q. What about the Clean Neighbourhoods and Environment Act 2005? | Q. Can you make a difference? | Conclusion | About this article | Links, further reading and reference | Light Pollution - Survey Results

Q. Does lighting make night safer?
A. Yes, in some cases it can. Some lighting is useful for road safety, on the street for pedestrians, so that we can see in our homes. But this does not mean that we should light everything, everywhere, this is just wasteful. There are some studies that show that road lighting can effect a small decrease in accidents at known black-spots. Lighting may decrease accidents at certain places, but excessive, poorly aimed lighting and the glare that it causes can be counterproductive and expensive.

In some cases lighting can actually be dangerous, a recent motorist's death in the UK was attributed to him being dazzled by a domestic floodlight which caused his car to leave the road, with tragic consequences. (I have had a similar incident where a garden floodlight came on and dazzled me to the extent that I nearly collided with an oncoming car. I reported this to the Police, some weeks later I noticed that the light had been removed!) In France it is not unusual to find that some streetlights are switched off around midnight, an economy that could be used elsewhere. Clearly there is much to be considered with regards the use of light.

BACK TO TOP Q. What is light pollution? | Q. What causes light pollution? | Q. What does light pollution affect? | Q. Is astronomy alone affected? | Q. Does it affect other living things? | Q. Does it affect the environment? | Q. Do security lights prevent crime? | Q. What does light pollution cost? | Q. Can light pollution be controlled? | Q. What about the Clean Neighbourhoods and Environment Act 2005? | Q. Can you make a difference? | Conclusion | About this article | Links, further reading and reference | Light Pollution - Survey Results

Q. What does light pollution cost?
A. It is extremely difficult to state just how much light pollution costs. While it is simple to say what may be lost or affected in some way, many of the things affected by light pollution are simply impossible to put a price tag on. For example, light pollution can degrade or destroy the view of the heavens but I would be deeply in debt to whoever could put a precise cost on that. (It has to be said that a decent view of the night sky is priceless anyway!) That said there are a few things that we can start to price. Let us for example take the cost of electricity for lights (or any other appliance for that matter).

Below is a simple table to illustrate the costs of electricity. The various power utilities charge varying amounts per unit (Kilowatt hours - 1000 watts consumed per hour) and varying charges depending on the time of day. The following prices are for powering a lamp or other appliance for 9 hours a day, all year round. A sample of typical lamp ratings are shown along the top. Differing charges are listed down the left. For example, a 100 watt lamp lit for 9 hours a day, all year round, charged at 5 pence per unit will cost 16.42.

                    WATTS
                      15w       25w       40w       60w      100w      150w      300w      500w
 KILOWATT   1p      0.49     0.82     1.31     1.97     3.28     4.92     9.85    16.42
 HOUR       2p      0.98     1.64     2.62     3.94     6.57     9.85    19.71    32.85
 COST       3p      1.47     2.46     3.94     5.91     9.85    14.78    29.56    49.27
 (Pence     4p      1.97     3.28     5.25     7.88    13.14    19.71    39.42    65.70
  per       5p      2.46     4.10     6.57     9.85    16.42    24.63    49.27    82.12
  unit)     6p      2.95     4.92     7.88    11.82    19.71    29.56    59.13    98.55
            7p      3.44     5.74     9.19    13.79    22.99    34.49    68.98   114.97
            8p      3.94     6.57    10.51    15.76    26.28    39.42    78.84   131.40
            9p      4.43     7.39    11.82    17.73    29.56    44.34    88.69   147.82

So far we have become aware of the many things affected by light pollution. Now, on price alone, perhaps we can start to grasp the costs of light pollution. And how it all adds up!

BACK TO TOP Q. What is light pollution? | Q. What causes light pollution? | Q. What does light pollution affect? | Q. Is astronomy alone affected? | Q. Does it affect other living things? | Q. Does it affect the environment? | Q. Do security lights prevent crime? | Q. Does lighting make night safer? | Q. Can light pollution be controlled? | Q. What about the Clean Neighbourhoods and Environment Act 2005? | Q. Can you make a difference? | Conclusion | About this article | Links, further reading and reference | Light Pollution - Survey Results

Q. Can light pollution be controlled?
A. Yes it can, but only by education and legislation can the trend towards more and unnecessary lighting be halted and reversed. For example, the UK Highways Agency has stated that future 'A' and 'M' Road schemes will be lit by "sky-friendly" fixtures. New and replacement street lights now feature "full cut-off" or "short cut-off" shielding that prevents almost all light from escaping above the horizontal. Many existing and old lighting fixtures are being replaced with "sky-friendly" fixtures.

There is a trend nowadays for road lighting to be better directed, not least because of the efforts of concerned bodies of astronomers such as the British Astronomical Association, Campaign for Dark Skies and the International Dark-Sky Association. Recently the Society was contacted by a contractor who was replacing lighting on the stretch of motorway nearby the Society's Observatory at Toothill. Assurances were made that the lighting would be of the full cut-off variety. The lighting contractor wanted to consult with us - something that would have seemed unlikely 10 years ago!

A country that has taken a lead in controlling light pollution is Czechoslovakia. The Czech government recently passed legislation which prohibits the use of indiscriminate lighting with fines of up to 1000 for non-compliance. Perhaps this will trigger similar moves elsewhere, one certainly hopes so for the sake of all those affected by excessive lighting.

Things are moving in the right direction. In February 2003, the Parliamentary Select Committee for Science and Technology began its investigation into light pollution. There was an informal meeting with astronomers from the British Astronomical Association's Campaign for Dark Skies (CfDS) and the Royal Astronomical Society (RAS) at the Greenwich Observatory in early June. Later, the committee took formal evidence in Westminster from CfDS, Guy Hurst (BAA President), the two Astronomers Royal, the RAS, the CPRE (Council for the Protection of Rural England, the Highways Agency, Ministers, PPARC, lighting professionals and local authorities. Written evidence was submitted by hundreds of societies and individuals.

The report is totally "sky-friendly". It does not oblige the Government to act; but its direct accusations of Government indifference and confusion on the subject of light pollution are such that they surely cannot be ignored. The Select Committee writes: "We regret that PPARC and the Government have adopted a defeatist attitude towards light pollution and astronomy..." The Select Committee supports proper control of excessive lighting: "Light trespass and glare affects astronomers, but can also affect us all. We recommend that obtrusive light should be made a statutory nuisance."

The full report by the Parliamentary Select Committee for Science and Technology can be seen at Her Majesty's Stationery Office website.

The battle is by no means won! Campaigners realise that the skies can never again be as dark as they were a century ago. But the optimum rural and urban night sky is achievable for all, if those in power allow it to happen. The Select Committee report is not a magic wand which will change the skies overnight. It is, however, a big stick with which to beat the decision-makers if they continue to close their eyes to the value and majesty of the environment above.

BACK TO TOP Q. What is light pollution? | Q. What causes light pollution? | Q. What does light pollution affect? | Q. Is astronomy alone affected? | Q. Does it affect other living things? | Q. Does it affect the environment? | Q. Do security lights prevent crime? | Q. Does lighting make night safer? | Q. What does light pollution cost? | Q. What about the Clean Neighbourhoods and Environment Act 2005? | Q. Can you make a difference? | Conclusion | About this article | Links, further reading and reference | Light Pollution - Survey Results

Q. What about the Clean Neighbourhoods and Environment Act 2005?
A. In 2005, largely as a result of the Parliamentary Select Committee for Science and Technology report in 2003, the United Kingdom passed the Clean Neighbourhoods and Environment Act. As a result light pollution is now deemed to be a nuisance in the same vein as noise or smoke. Some might argue that the Act does not go far enough since there are several exclusions within the Act. But, overall it is a positive step forward in the battle to reduce light pollution. Maybe future revision to the Act will go to further control and reduce light pollution.

Some domestic lighting is not designed to restrict emissions to the premises meant to be lit, causing light trespass and nuisance to many - and not just to astronomers. The fact that light was not legally considered a pollutant under the Control of Pollution Act, unlike noise and smoke, meant that victims of light pollution had little redress, and the stars had no protection in law. Things have changed!

The Clean Neighbourhoods and Environment Act 2005 now means that individuals can do something about nuisance lighting. It must be stated that not all lighting is currently covered by the Act but domestic, private lighting is. If a neighbour's light or lights are causing a nuisance it is now possible to get something done about it.

The best approach is to contact the person whose light is causing a nuisance, often they do not realise that they are causing a problem in the first place. It may be possible to ask the person to move, re-aim or adjust the light. In that instance the problem is quickly resolved. But, if you do approach a neighbour who then refuses to do anything you will have little choice but to resort to the law.

Every local and borough council in the UK has an Environmental Health Officer. By contacting this person you can make a formal complaint about nuisance lights. The catch is that the Environmental Health Officer has to agree with you that the lights concerned do constitute a nuisance. But if they do agree, they can compel a person who causes light pollution to take corrective action.

BACK TO TOP Q. What is light pollution? | Q. What causes light pollution? | Q. What does light pollution affect? | Q. Is astronomy alone affected? | Q. Does it affect other living things? | Q. Does it affect the environment? | Q. Do security lights prevent crime? | Q. Does lighting make night safer? | Q. What does light pollution cost? | Q. Can light pollution be controlled? | Q. Can you make a difference? | Conclusion | About this article | Links, further reading and reference | Light Pollution - Survey Results

Q. Can you make a difference?
Yes, you can make a difference to light pollution. Doubtless you will be aware of environmental issues like greenhouse gases, global warming, dwindling resources and so forth. Chances are you already take steps to reduce the impact you have on the environment - recycling, using public transport, insulation - there are many ways you can make a difference. Why not go one bit further and reduce the impact that lights have on the environment. Using low-energy bulbs, fitting lower wattage lamps, switching lights off when they are not needed.

If you do have exterior lighting consider whether you really need it. Again, it is necessary to repeat that there is no proof that lights prevent crime. If you must have exterior lighting consider what brightness it should be. Many exterior domestic lighting situations seldom require more than a few tens of watts power at most. Can the wattage of the lamp be reduced? Do you really need a 500 watt lamp when, say, 50 watts would be enough? Consider the following:

If your own exterior lighting complies with all reasonable considerations, what about others? If your neighbour has lighting that affects you, have you considered raising the issue with them? They may be unaware that they are causing a problem. If a neighbour has lights that you consider a nuisance you can do something about it by raising the issue with your local council's Environmental Health Officer.

There are many ways that exterior lights can be made to have a markedly reduced impact on the environment. And it is a win-win situation. Less light means less light pollution. Reduced power consumption means less fuel consumption. Reductions in consumption mean lower bills. Everyone wins in the short and long term!

BACK TO TOP Q. What is light pollution? | Q. What causes light pollution? | Q. What does light pollution affect? | Q. Is astronomy alone affected? | Q. Does it affect other living things? | Q. Does it affect the environment? | Q. Do security lights prevent crime? | Q. Does lighting make night safer? | Q. What does light pollution cost? | Q. Can light pollution be controlled? | Q. What about the Clean Neighbourhoods and Environment Act 2005? | Conclusion | About this article | Links, further reading and reference | Light Pollution - Survey Results

Conclusion.
All this may suggest that astronomers want all lights switched off - this is not true! We want to see the promotion and installation of good lighting. Lighting that is not too bright, does not blot out the night sky and waste energy. Lighting that is sensible, economical, properly installed and regulated. We would like to see the night time environment and Earth's resources preserved for future generations.

These sights have been, since about 1950, gradually taken away from us by a baleful glow of wasted light, escaping from poorly aimed and often over-bright artificial lamps, to be scattered by airborne particles and aerosols. Over great cities, towns and even small villages, light pollution robs us, in the very last millisecond of its journey, of the starlight which may have travelled for hundreds, thousands, or even millions of years to reach our planet.

Here is a modern irony: spacecraft and telescope technology can deliver breathtaking views of the near and far universe, while the technology which lights our nights simultaneously draws a veil across the night sky. Add to skyglow the effects of aircraft contrails, sometimes spreading across continents, the radio 'clutter' which frustrates radio astronomy, and the space debris orbiting Earth: are we cutting ourselves off from the direct experience of the rest of the universe? Will the children of the late 21st century see stars only on screensavers and in cinemas?

BACK TO TOP Q. What is light pollution? | Q. What causes light pollution? | Q. What does light pollution affect? | Q. Is astronomy alone affected? | Q. Does it affect other living things? | Q. Does it affect the environment? | Q. Do security lights prevent crime? | Q. Does lighting make night safer? | Q. What does light pollution cost? | Q. Can light pollution be controlled? | Q. What about the Clean Neighbourhoods and Environment Act 2005? | Q. Can you make a difference? | About this article | Links, further reading and reference | Light Pollution - Survey Results

About this article. . .
This article was written by Derek Haselden with the assistance of Bob Mizon (Wessex AS), Co-ordinator of the Campaign for Dark Skies (CfDS). Much of this article came from CfDS and IDA material. Please feel free to copy and distribute copies of this document but please acknowledge the authors. Also, please do not alter the content without the permission of the authors.

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Links, further reading and references about light pollution
For your convenience I've listed a few useful websites below. If you wish to read more on the topic of light pollution you'll get several thousand references by typing in 'Light pollution' into you favourite search engine.

A publication worth reading is 'Blinded by the Light?', the new CfDS handbook. Further details of this can be found at the BAA CfDS (British Astronomical Association, Campaign for Dark Skies) website. The book is a snip at only 3. It addresses several issues connected with light pollution including:

CfDS (British Astronomical Association, Campaign for Dark Skies)
IDA (International Dark-Sky Association)
RAS (Royal Astronomical Society)
RSPB (Royal Society for the Protection of Birds)
CPRE (Council for the Protection of Rural England)

BACK TO TOP Q. What is light pollution? | Q. What causes light pollution? | Q. What does light pollution affect? | Q. Is astronomy alone affected? | Q. Does it affect other living things? | Q. Does it affect the environment? | Q. Do security lights prevent crime? | Q. Does lighting make night safer? | Q. What does light pollution cost? | Q. Can light pollution be controlled? | Q. What about the Clean Neighbourhoods and Environment Act 2005? | Q. Can you make a difference? | Conclusion | About this article | Light Pollution - Survey Results

LIGHT POLLUTION, READER SURVEY RESULTS
This page recently hosted two survey forms where readers could enter their opinions about issues surrounding light pollution. With the first survey readers were encouraged to complete the form before they had read this page, the second survey after they had read this page. The survey forms were first posted in September 2003 and up until 15th February 2007 this light pollution page was visited nearly 5000 times. In that time, up to April 2006, 100 forms for the first survey were completed.

The second survey form had its 100th form posted on 15th February 2007. The overall return rate was roughly 2% for each survey, that is, only 2% of readers completed the forms! Despite this apparently low turn-out many clear conclusions can be drawn. It was also interesting to note that throughout that time clear trends emerged which barely changed throughout the intervening time, so at least the slow retun rate of forms showed consistent responses. The results of these two surveys appears below...

LIGHT POLLUTION SURVEY RESULTS
16th February 2007

Here are the results of the first survey, completed by readers before they had read this page.

LIGHT POLLUTION - SURVEY 1 - completed before reading this page. YES NO DON'T
KNOW
Q1. Did you find this page via a Search Engine? 81% 19% 0%
Q2. Did you find this page by following a link from another webpage? 17% 82% 1%
Q3. Did you visit this page after it was recommended to you by someone? 11% 84% 5%
Q4. Are you an astronomer or are you very interested in astronomy? 52% 45% 3%
Q5. Have you heard of the Campaign for Dark Skies or the International Dark Skies Association? 55% 42% 3%
Q6. Do you know what is meant by the term 'Light pollution'? 90% 8% 2%
Q7. Do you know what causes light pollution? 89% 10% 1%
Q8. Do you believe that lights help prevent crime? 56% 39% 5%
Q9. Do you believe that lighting can make night safer? 62% 35% 3%

Comments
The first 3 questions were aimed at trying to find out how people were finding the page, the results are pretty self-explainatory. With Question 4 (Are you an astronomer or are you very interested in astronomy?) I would have expected a high proportion of astronomers to respond to that question but what emerges, and this has already been stated elsewhere, is that it is not just astronomers who are concerned about light pollution. Clearly, people with no interest in astronomy care about light pollution as well.

Question 5 (Have you heard of the Campaign for Dark Skies or the International Dark Skies Association?) showed mixed results. It would be good if these groups got wider coverage but it does appear that their message is getting across. On the other hand, unless one has a specific interest in astronomy, light pollution, and environmental issues, one may not have heard of these organisations. It is interesting to note that the responses for Questions 4 and 5 are almost identical. This suggests that pressure groups like the CfDS and IDA have limited exposure outside of the astronomical community. But at least with Questions 6 and 7 it is pleasing to see that light pollution and its causes seem to be well understood.

What is not understood, or at least misunderstood, is lighting and crime. Question 8 shows the belief that lights prevent crime is quite widely held. (More of this question later.) The faith that people have in lights preventing crime seems to have something in common with other widely held beliefs which I need not mention here. But it is worth repeating that which has already been written elsewhere on this page - there is no evidence that lights make a significant impact on reducing crime.

With little doubt, certain situations can benefit from lighting although it must be said that the lighting must be sensibly and sensitively located. There is a suggestion (and many people I have spoken to have highlighted this) that people 'feel' safer in lit areas but this should not be confused with actual, proven safety. Safety concerns can be addressesed by lighting but I should emphasise the the lighting must thoughtful, not too bright or excessive. It must be well directed or else it may prove to be inneffective, even dangerous.

So, moving on, here are the results of the second survey, completed by readers after they had read this page...

LIGHT POLLUTION - SURVEY 2 - completed after reading this page. YES NO DON'T
KNOW
Q1. Do you feel you now know what is meant by the term 'Light pollution'? 98% 2% 0%
Q2. Do you feel you now understand what causes light pollution? 99% 1% 0%
Q3. Do you believe that lights help prevent crime? 33% 65% 2%
Q4. What kind of area do you live in? (Results
below)
- -
Q5. What degree of light pollution in the night sky is apparent from where you live? (Results
below)
- -
Q6. Are you able to see the Milky Way from where you live? 21% 75% 4%
Q7. Are you able to see the the main constellations from where you live? 57% 37% 6%
Q8. Do you think legislation and or regulation is necessary to control light pollution? 93% 5% 2%
Q9. Do you have exterior lighting which shines above the horizontal? 10% 88% 2%
Q10. Has anyone in your area reported problems with intrusive lighting? 35% 56% 9%
Q11. Have you approached anyone locally about poor lighting practice? 43% 52% 5%
Q12. Has this page provided you with the information you require? 91% 7% 2%

Comments
In some respects the two surveys were designed to complement each other as well as gauge how opinion had been affected by reading this page. The second survey went a little further in an attempt to find out how other matters not addressed by the first survey were affecting people.

A very positive note sounded by the second survey was that an ovewhelming majority of people know what light pollution is and that they know what causes it, the answers to questions 1 and 2 clearly show this.

Back to that contentious issue, whether lights have an effect on crime, the responses to that question show something interesting. In the first survey, supposed to have been answered before reading the page, the results were 56% saying they thought lights prevented crime, 39% thought it had no effect, 5% didn't know. In the second survey, supposed to have been answered after they had read the page, the results were quite different. Give or take a few percent the results were reversed with only 33% saying they still thought lights prevented crime but that now 65% thought lights made no difference, 2% didn't know. If these responses are truthful then it appears that this page has affected opinion on the matter and not so many people still hold onto the faith that lights prevent crime. Personally, I think this a small victory in consciousness-raising and I can only hope that this page continues to make people think more carefully about light pollution as a whole.

Questions 4 and 5 related to levels of light pollution and location. More of this further down this page...

Question 6 (Are you able to see the Milky Way from where you live?) shows something worrying but nothing surprising. Only 21% claim to be able to see the Milky Way from where they live but 75% say they cannot, 4% are unsure. I checked back through the returned survey forms and found that the majority (about 90%) of those who said they could see the Milky Way lived in a village, rural or countryside location. Given the majority of people (according to the survey three quarters or more of people) live in built up areas one can only sadly conclude that the Milky Way is all but lost to town and city dwellers due to light pollution.

Question 7 (Are you able to see the the main constellations from where you live?) doesn't throw up many surprises either with 57% claiming to be able to see the main, bright constellations from where they live, 37% said they couldn't see them, 6% were unsure. That remaining 6% could well be lumped in with the rest who say thay cannot see the constellations. Most of the bright stars that make up the brighter constellations are down to about the 3rd magnitude. If this is the case then on a clear night urban dwellers are only able to see 200 stars, 300-odd at most, fewer still if their area is badly light polluted. A dark location would give visual access to over 2000! Another way of saying this is that from an urban viewing site only 10% of all visible stars can be seen. And that might be an optimistic projection!

Question 8 (Do you think legislation and or regulation is necessary to control light pollution?) shows that 93% think legislation is necessary to control light pollution, only 5% thought it unnecessary. Recent legislation has gone some way to addressing the problem, some may argue that more statutes are needed and this is confirmed by this survey result.

Question 9 (Do you have exterior lighting which shines above the horizontal?) shows that most (88%) have a responsible and thoughtful attitude to lighting. What is needed now is for everyone else to act that way. Many commercial, industrial, and domestic premises should be doing more to address how sensitively their exterior lighting is arranged.

A minority of answers to Question 10 (Has anyone in your area reported problems with intrusive lighting?) said that they were aware of probems with intrusive lighting being reported. This would appear to tally up with the responses to Question 11 (Have you approached anyone locally about poor lighting practice?) which indicates that despite people being aware of a problem, or actually having problems with intrusive light, it appears that too few people are willing to complain. To reiterate that written further up this page, many perpetrators of excessive or badly installed lighting are not likely to be aware that they are causing a problem. If you complain there has to be a good chance that they will do something about it. If they don't do something about it there are recourses in law to follow. But, only if you bring it to their attention!

Finally, the majority said that they found this page helpful and that it contains the information they required. It is things like that which make the effort of writng and maintaining this page worthwhile.

And now the responses to Questions 4 and 5...

Q5. Degree of light pollution
Q4. Area lived in None Slight Noticeable Strong Severe TOTAL
Rural/countryside 0% 1% 5% 3% 2% 11%
Village 0% 1% 6% 4% 3% 14%
Small town 0% 6% 7% 8% 3% 24%
Large town/city suburb 1% 3% 5% 21% 15% 45%
City centre 1% 0% 1% 2% 2% 6%
TOTAL 2% 11%24%38%25%-

Comments
Make of this what you will! The mere 2% who said that they had no light pollution (you lucky, lucky people) said they lived in a large town, city suburb or city centre area. While I would admit that peoples appraisal of light pollution may be subjective I think it safe to say that those 2% are spurious answers! Ignoring that 2% however leaves one with the stark conclusion that everyone who responded to the survey was affected by light pollution. Perhaps the only people who would respond to a page such as this and then complete the survey would be concerned about light pollution anyway. Even so, the BAA survey mentioned further up this page asserts that possibly 90% of the UK population is affected by light pollution and the results of the survey on this page show similar results.

It took me a while to think why only 6% of respondents said they lived in a city centre but it makes sense when you think that most premises in city centres are shops. So, not many people actually live in a city centre. The definition of what is a village, town, or city is unclear with respect of population. I think it safe to say that any town or city will be afflicted by light pollution. So while 75% of respondents fall into this category of dwelling place they contain a disproportionately high percentage of people overall and a greater density of people per square mile as well. This goes some way to enforce the concept of about 90% of people being affected by light pollution as stated by the BAA.

Also, note the high proportion of people who responded to Questions 4 and 5 by answering that their experience of light pollution was that of noticeable, strong, or severe, no matter where they lived. Again, they may only be responding that way because they were reading this page because they were affected by light pollution, so one should not be surprised by those results.

All in all, conducting this survey has been interesting and informative and I hope you find the results of interest as well. What would be interesting is to conduct a survey in a few years and see what, if anything, has changed.

BACK TO TOP Q. What is light pollution? | Q. What causes light pollution? | Q. What does light pollution affect? | Q. Is astronomy alone affected? | Q. Does it affect other living things? | Q. Does it affect the environment? | Q. Do security lights prevent crime? | Q. Does lighting make night safer? | Q. What does light pollution cost? | Q. Can light pollution be controlled? | Q. What about the Clean Neighbourhoods and Environment Act 2005? | Q. Can you make a difference? | Conclusion | About this article | Links, further reading and reference | Light Pollution - Survey Results

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Derek Haselden, Solent Amateur Astronomers, Campaign for Dark Skies, 2009