Preventing Light Pollution:

The Four Point Plan

Sky glow (light pollution) arises from a combination of artificial lights emitted directly into the sky from light fittings, and from light reflected up into the sky from buildings and the ground. Hence, the BAA Campaign for Dark Skies currently recommends that:

1. Lights should be installed in full cut-off housings, to prevent light being emitted above the horizontal.



2. Although astronomers prefer the light emitted by low pressure sodium lamps (as this can be filtered out), high pressure sodium lamps are acceptable provided no light is emitted above the horizontal.



3. 'Over-lighting' must be avoided. Using only the correct amount of light for the task in hand, according to accepted standards, will reduce the amount of reflected light contributing to sky glow.



4. Unnecessary night-time lighting, particularly decorative flood-lighting, advertising lighting and sports floodlighting, should be switched off at 11pm or midnight to reduce over-night pollution.