LIGHT POLLUTION OF NORTH YORKSHIRE

  The National Park area runs interesting courses on Astronomy at the Danby Centre. Faint sky objects, especially comets, are now becoming more difficult to see because of light pollution.

  Outdoor lighting has become a necessary integral part of society. Light pollution is a by-product of outdoor lighting. Light pollution can be reduced by lighting only what is actually needed, when it is needed and to the appropriate level. This letter discussed the three elements of light pollution which are sky glow, light trespass, and glare, and gives examples and recommendations for minimising or eliminating the undesirable effects of each element when designing and using outdoor lighting.

  We light our outdoor night environment to meet certain societal goals, such as increasing safety and security, and to enhancing economic development, as well as highlighting historic areas or landmarks of cities or towns. Our society has become a 24-hour society and night-time lighting has become a necessity to facilitate using our roadways and downtown areas.

  Light pollution is a by-product of lighting at night, especially when we use inefficient luminaires and lamps and when we light to excessive levels. We can minimise our impact on light pollution by lighting more efficiently. When we choose efficient luminaires and lamps, fewer lamps may be required to meet the lighting objectives, resulting in less wasted light emitted into areas where the light is not needed. Light pollution is an unwanted consequence of outdoor lighting and includes such effects as sky glow, light trespass, and glare.

  Sky glow is a brightening of the sky caused by both natural and human-made factors. The key factor of sky glow that contributes to light pollution is outdoor lighting.

  Light trespass is light being cast where it is not wanted or needed, such as light from a streetlight or a floodlight that illuminates a neighbour's bedroom at night making it difficult to sleep.

  Glare can be thought of as objectionable brightness. It can be disabling or discomforting. There are several kinds of glare, the worst of which is disability glare, because it causes a loss of visibility from stray light being scattered within the eye. Discomfort glare is the sensation of annoyance or even pain induced by overly bright sources Think of driving along a dark road when an oncoming car with bright headlights suddenly appears. The sudden bright light can be uncomfortable and make it difficult to see. Discomfort and even disability glare can also be caused by streetlights, parking lot lights, floodlights, signs, sports field lighting, and decorative and landscape lights.

25 April 2003