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Cover Image: Vincent van Gogh, The Starry Night, June 1889 (oil on canvas)/Museum of Modern Art, New York/Bridgeman Contents CHAPTER 1 INTRODUCT I ON 1 CHAPTER 2 A GROW I N G SEN S E OF LO ss 5 CHAPTER 3 SOC ial BENEF I T S A ND DR A W ba CK S OF OUTDOOR Lig HT I N G 9 CHAPTER 4 IMP A CT S OF Lig HT PO ll UT I ON ON OR ga N is M S A ND ECO S Y S TEM S 14 CHAPTER 5 RO A D Lig HT I N G TECHNO L O G Y : AN OPPORTUN I TY A ND A CH all EN G E 22 CHAPTER 6 CONC L U si ON S A ND RECOMMEND A T I ON S 28 REFERENCE S 31 Appendix A BA CK G ROUND TO THE COMM issi ON ’S REPORT ON ART I F I C ial Lig HT I N THE ENV I RONMENT 35 Appendix B MEM B ER S OF THE COMM issi ON 39 Chapter 1 INTRODUCT I ON There are two kinds of light – the glow that illuminates, and the glare that obscures. James Thurber 1.1 Imagine a vista of outstanding natural beauty, to say nothing of historic and cultural signif- icance, permanently obscured from public view by a cloud of non-toxic, but visually impene- trable, artificial vapour. Such a prospect seems unthinkable in Britain today. Yet we seem to tolerate the daily destruction of arguably the most culturally universal and historically pristine of natural vistas – the night sky, filled with constellations of stars, and planets and galaxies. The responsible pollutant, however, is not an impenetrable vapour, but the light that we so freely emit into our surroundings. 1.2 If inescapable visual pollution were the only effect of light in the wrong place it would be bad enough, but there are other consequences of the ubiquity of current outdoor lighting in towns and cities, along highways and in industrial locations. Light is one of the most potent agents interacting with biological systems. Responses to light include phototropism (movement or growth towards or away from light) and stimulation of hormone production, including the fine tuning of cyclical changes. That living organisms have evolved varying degrees of sensitivity to light should surely give us pause for thought as we pollute our night-time environment with it. 1.3 For the most part, light at night provides valuable benefits; it is something that we deliberately seek and can be an essential aid to safety. However, we consider the experience of light in the wrong place or at the wrong time as light pollution; the timing of illumination may be as important a factor as the actual level of light. Light pollution can take various forms, and may originate from both diffuse and point sources: Glare: The excessive contrast between bright and dark areas in the field of view. Light trespass: Unwanted light, for example from adjacent properties and activities. Light clutter: The excessive grouping of lights, for example in roadside advertising which can prove a dangerous distraction to motorists. Light profligacy: Over-illumination which wastes energy and money. Sky glow: A combination of reflected and refracted light from the atmosphere. A major effect of sky glow at night is to reduce contrast in the sky. This is the most pervasive form of light pollution and can affect areas many miles from the original light source. An absence of darkness: Artificial light makes experiencing natural night-time lighting conditions impossible in many parts of the country. 1 Artificial Light in the Environment 1.4 Over the last 150-200 years a huge change has taken place in the UK environment. The moon and stars are no longer the only major sources of light at night. Illumination of our streets and roads, our buildings and agricultural greenhouses, as well as other sites, now spills into the night. The consequences of this for wildlife and human health and wellbeing are largely unknown. 1.5 Wherever artificial light floods into the natural world there is the potential for some aspect of life and its rhythms – migration, reproduction, feeding – to be affected. For instance, man-made light is known to cause confusion to migrating birds, often with fatal outcomes. Exposure to artificial light, which simulates short nights, is known to induce early breeding in some species of birds. Another well-known example is the effect on the feeding behaviour of bats caused by insects clustering around outdoor light sources. 1.6 Human health problems have been associated with exposure to light at night inhibiting production of melatonin. The inhibition of the production of melatonin is associated with the incidence of certain breast cancers.1 It should be emphasised that, so far, this possible effect has been confined to night shift workers exposed to high levels of indoor lighting; we do not deal with this effect further in our report where the focus is on light in the outdoor environment, but more recent work suggests changes in the nature of external lighting may mean this is more of an issue in the future.i However, the association between light at night and melatonin production is indicative of the largely unresearched effects that light can have on all organisms. Furthermore, people report negative health impacts from sleep disturbance due to light intrusion into their homes from road lamps that are left on all night.2 They may also experience stress from unwelcome illumination, such as security lighting, spilling onto their property from that of their neighbours. 1.7 The Royal Commission’s 26th report, The Urban Environment,3 identified light pollution as a significant factor shaping local environmental quality, but did not consider it in any depth as it was outside the main focus of that report. The Commission has undertaken the present short study in recognition of the increasing pervasiveness of outdoor artificial light and concerns that its effects are becoming progressively more significant. 1.8 The loss of visual amenity represented by the obscuring of the night sky and the potential deleterious effects on photosensitive organisms are not the only issues raised by light pollution. Among the obvious consequences is the waste of energy and money associated with allowing light to escape upwards towards the sky when the purpose of most outdoor lighting is to enable people to go safely and securely about their business on the ground. Even the floodlighting of public buildings is better achieved when light is focused on the structure and not dissipated into the sky around it. Huge quantities of light are needlessly shone into space from cities around the world each year.4 The carbon emissions associated with such energy profligacy must also be enormous. However, we do not dwell on the energy and climate change implications of light pollution in this report, as we regard these as part and parcel of wider problems that are already well recognised, although we touch on the issue where appropriate.ii i There is some evidence to suggest that blue-enriched white light is very effective at keeping people alert throughout the day and in re-setting the body clock, so that we sleep better at night. See for example: van Bommell, W. (2006). The biological effect of lighting. Lighting Journal, 71(1); and Donoff, E. (2009). Light’s impact on health is playing a central role in design. Lighting Journal, 74(1). ii In 2006, lighting (predominantly interior lighting) accounted for around 20% of electricity consumption in the UK, with public lighting estimated to represent 1% of the total (personal communicaltion from Energy Statistics and Analysis, Department for Business, Enterprise and Regulatory Reform (BERR), now Business, Innovation and Skills (BIS), November 2007). 2 Introduction 1.9 We have also chosen not to revisit the well-known deleterious effects of light pollution on astronomy.