Light pollution is excessive, poorly directed or unnecessary artificial light at night
– Wastes energy and money.
– Affects the natural day-night/light-dark cycle under which all species and ecosystems on Earth have evolved.
– Endangers night time habitats and disrupts natural rhythms (e.g. circadian and saisonal) of both diurnal and nocturnal species.
– Destroys the natural darkness of nocturnal landscapes and obscures the view of the star-filled sky.
– Disorients insects and other animals, thereby reducing ecosystem services.
– Affects human well-being and health through its association with insomnia, obesity, metabolic disorder and hormonal cancers.
– Potentially decreases safety due to glare.
– Causes annoyance and reduces privacy by obtrusive light.
Light at Night Done Right
3 tips for outdoor illumination
Direction
Overhead lamps intended for public or private outdoor area lighting should never emit light directly above the horizontal and as little light as possible at shallow downward angles.
– Upward light provides no benefit and light at shallow angles causes glare that reduces visibility.
– We recommend a general requirement of no direct “uplight” (i.e. ULOR=0 for all classes).
Color
– Exposure to blue light should be avoided during the evening and night. Lamps used for outdoor areas should have a correlated colour temperature of 3000 K or lower.
– Blue light is more glaring, especially for older individuals.
– The circadian system of mammals and humans is most sensitive to blue light.
– The attraction of the light to most flying insects increases with the blue and UV light ratio.
– Blue photons are more likely to be scattered by the atmosphere and returned to Earth as skyglow.
Intensity
– Install controls to dim or turn off lights, when not in use. Use only as much light as needed for the specific purpose. Illuminance levels in standards for street lighting like the European Standard EN 13201 and the ANSI/IES RP-8 for the US need re-evaluation and scientific justification for the lighting levels they recommend, because:
– The illuminance levels of most lighting infrastructure in Europe are often lower than the recommendations in EN 13201, but nevertheless successfully address public safety needs.
– The energy and CO2 emissions associated with outdoor lighting would increase dramatically if even the minimum limits recommended by the standards were adopted in all European countries
