According to the International Dark-Sky Association, light pollution is "any adverse effect of artificial light including sky glow, glare, light trespass, light clutter, decreased visibility at night, and energy waste."
Light pollution is growing at an alarming rate of 6% per year, which is four times the rate of population growth (Naeye, 2010). As of 2008, there is 1 street light per every 10 people in the United States (Grow, 2008). This has increased from 1 street light per every 15 people in 1970 (Garstang, 2004).
Light pollution is caused when artificial light is overused or inefficiently used. An estimated 30% of all energy used in outdoor lighting is scattered into the atmosphere as light pollution. If this waste was eliminated, it would save the United States approximately $7 billion dollars per year on energy bills.
The reduction in carbon dioxide emissions would be the equivalent of removing over 9.5 million cars from the road (Gallaway 2010). Reducing light pollution benefits both the environment and the economy.
Two-thirds of the United States population cannot see the stars of the Milky Way because of sky glow. However, light pollution is more than just a nuisance to astronomers; it is a serious health hazard to humans, plants, and animals.
This online bibliography includes links to light pollution websites and ordinances, research on light pollution developments and opportunities, and guidance for both new and retrofit installations.