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Light Pollution

Introduction

Light pollution can be defined as any adverse effect of man-made light. In our energy rich society we have all come to rely on lighting in our working, living, and travelling environments. Light gives a sense of security and safety at night when walking and driving in busy urban and quiet rural areas.

But light can also affect humans and wildlife in detrimental ways as a form of pollution although it is not classed as a statutory nuisance. Light pollution is not governed by any legislation but is the cause of complaint from many sectors of the population. These objections to light pollution may lead to legislation in the future.

Effects of Light Pollution

Street lighting can affect the visual aspects of a whole landscape. A deserted moorland can be illuminated at night by motorway lights. A landscape horizon interrupted by the night glow of a nearby towns' street lighting. These all detract from the beauty of the natural environment.

Birds use the moon as a directional reference, however on moonless nights they are attracted to tall light sources instead. Nocturnal mammals like badgers and otters are confused by bright lights, and this could dissuade them from using favoured feeding grounds if they are artificially lit.

Moths especially are attracted to street lamps and can congregate in large numbers to feed and breed. This may cause an overpopulation in these lit areas and an exhaustion of feeding habitat, leading eventually to starvation.

Glare can be produced by lights against a dark background which can prove annoying to people. Light trespass can be disturbing to neighbours, for example when security lights spill beyond the boundary of an adjoining property. Street lights especially produce a sky glow at night which reduces the ability of astronomers to see the fainter stars in the sky.

Methods of reducing Light Pollution

• The use of low pressure sodium lamps instead of high pressure sodium or mercury lamps. The latter emit light on broader wavelengths including ultra-violet which attract more insects.
• Fit shades to street lamps and flood lights so directing the light downwards reducing light pollution together with the use of less powerful bulbs.
• Engineers can use a Downward Light Output Ratio (D.L.O.R) to measure the effectiveness of lamps.
• Turn off lights near to environmentally sensitive areas if this can be done without endangering public safety. Existing planning regulations help reduce the use of new lighting in these areas but these powers are limited.

Environmental Zones:

'Environmental Zoning' covering four zones, reflects the "environmental sensitivity" of an area to types and levels of lighting. For example, no artificial lighting is allowed in National Parks so protecting local ecology, but bright illumination like neon lights are allowed in cities.

Following these inexpensive guidelines we can help reduce light pollution, save energy and money and create a more favourable environment for both humans and local wildlife.

Due to the lack of data available at the local Hertfordshire level and the difficulty in recording or identifying light pollution it is not possible to assess the polluting affects on the County. However, future research may begin to reveal the true extent of light pollution.in the County.

For further information contact:

1. Your Local District/Borough Council.
2. British Astronomical Association web site: http://www.u-net.com/ph/cfds/ile/ile-gd-e.htm
3. The Institution of Lighting Engineers
   Tel: (01788 576492)
4. Hertfordshire Environmental Records Centre -Tel: (01462) 432454