Impact of outdoor lighting on man and nature

In this advisory report, the Health Council draws attention to the ongoing loss of darkness in the evening and at night and to the consequences of this loss for landscape quality and the human environment. Modern developments such as urbanization, increased motor traffic, increased greenhouse horticulture, more flexible working hours, a growing demand for outdoor sports facilities and an increasing tendency to floodlight business premises and historic buildings mean that darkness is being eliminated in a growing number of increasingly large areas. For a variety of reasons, many people regret these changes. Annoyance in residential areas and worries about possible harm to plant and animal life also warrant additional attention to this matter in the policy of central government and other regulatory bodies.

Plant and animal life

Outdoor lighting at night-time can influence the life cycle and behaviour of animals in many ways. The effects vary greatly depending on the animals concerned. Outdoor lighting is often accompanied by other disturbing, barrier-forming factors such as traffic noise. In particular for birds, insects and amphibians, it has been observed that outdoor lighting influences behaviour as animals are disoriented, attracted or repelled by the light, thus increasing the chance of exhaustion and death. For some species with small, isolated populations, this can cause local extinction. In a recent field study it was observed that street lighting affects the density of local populations of black-tailed godwit. There are no indications that outdoor lighting has a serious detrimental effect on wild plants.

Man

Studies have shown that people living in the immediate vicinity of greenhouses and sports fields were annoyed by the illumination of their houses or gardens, the direct view on the light sources or the glow above them. The percentages of people who experience moderate or serious annoyance vary from 5 to 15. In particular the glow above greenhouses is perceived as a nuisance by residents. Walkers in the evening period are annoyed by the direct view of the light from greenhouses. Over the next few years, the number of persons affected will increase due to the growing use of outdoor lighting.

It has been shown in laboratory experiments that a disturbance of the day-night rhythm has negative physical and psychological effects on human beings. However, such disturbances only occur at relatively high light intensities. Although epidemiological research on this matter is inconclusive, it cannot be ruled out that, in combination with other stress factors in the environment, outdoor lighting has a long-term detrimental effect on health due to stress associated with a shortening of the evening and night.

Loss of darkness as a ’primordial’ quality in rural areas

The plans for new urban development locations, industrial estates and various large infrastructural projects such as railways and airports mean that the use of outdoor lighting in the Netherlands will increase continuously in the coming years. Also in rural areas, which now are still relatively dark at night, outdoor lighting is set to increase with the development of housing, business premises and greenhouses, as well as the creation of new facilities for sports and recreation coupled with their intensified use. The disappearance of those still dark areas will promote the loss of diversity as well as the fragmentation of the Dutch nocturnal landscape.

A social science perception survey showed that people attribute importance to nature experiences, including silence and darkness. The Health Council supports the calls of nature conservation organizations to preserve darkness as a ’primordial’ quality of the landscape in rural areas, not only for nature itself but also for people, who need the opportunity to wind down in surroundings very different from those of today’s hectic 24-hour society (compensation value).

Further research

If a better picture of the ecological consequences of lighting is to be obtained, a field study over a period of several years is necessary, in which the effects of lighting in combination with other disturbing and fragmenting factors, including traffic noise, are examined. Research into annoyance in the immediate living environment is particularly relevant for the derivation of guidelines for the various applications of outdoor lighting.

The present advisory report underlines that people’s perception and appreciation of the landscape quality and the value of darkness and silence as essential elements play an important role in the general discussion on ’light nuisance’. Specific socio-psychological research into people’s perceptions is needed to enable the inventory of opinions of the Dutch population on the value of darkness in the context of their views on nature and nature experiences.

Legislation

Despite the lack of systematic practical knowledge from empirical research on the ecological consequences of nightly outdoor light, there are sufficient indications that support the current ’No unless’ policy of the Public Works and Water Management Department on street lighting in nature conservation areas. The need for lighting from a road safety viewpoint must always be carefully balanced against the possible adverse effects on animal life.

The policy of central government with regard to outdoor public lighting should become part of an integrated national approach for protection and improvement of the quality of the natural environment in rural areas and in particular in areas that have a restrictive policy with regard to building, infrastructural works and the like. One possibility is the creation of light abatement areas in analogy to the current noise abatement areas. If ’light nuisance’ were explicitly included in the environmental policy as part of the environmental theme ’disturbance’, the carry-over to other government bodies could be stimulated.

Legislation for reduction of the nuisance in the living environment from lighting at sports facilities and assimilation lighting in greenhouses is already in force or under preparation. Control of the enforcement could, however, be tightened up. Guidelines for dealing with nuisance from floodlighting and illuminated advertisements must still be developed.