As many homeowners, you are taking steps to reduce your carbon footprint at home. You dutifully recycle glass, metal, paper, and plastic waste each week. You replace all the incandescent light bulbs in your home with energy-efficient compact fluorescent lamps (CFL) or light-emitting diode (LED) bulbs. However, you may be unwittingly contributing to carbon emissions and interfering with delicate ecosystems through light pollution.
Light pollution, unlike other forms of contamination and waste, remains largely overlooked and unregulated in many countries. Learn the cause, types, and effects of light pollution, and how adjusting your outdoor lighting habits can reduce this form of waste.
Light pollution, also known as photopollution or luminous pollution, is the excessive, misdirected or invasive use of artificial outdoor lighting. Mismanaged lighting alters the color and contrast of the nighttime sky, eclipses natural starlight, and disrupts circadian rhythms (the 24-hour processes of most organisms), which affects the environment, energy resources, wildlife, humans and astronomy research. The threat of light pollution continues to grow as the demand for artificial lights increases each year.
Photopollution is not a new phenomenon. Over the last 50 years, as countries became affluent and urbanized, demand for outdoor lighting increased and light pollution sprawled beyond the city limits and into suburban and rural areas. This form pollution is now prevalent in Asia, Europe, and North America, particularly in cities like Los Angeles, New York and Washington D.C. In 2008, National Geographic magazine named Chicago the most light-polluted city in the United States.
However, the most light-polluted spot in the world is Hong Kong, China. In March 2013, the University of Hong Kong named the city the most light polluted in the world. A study by the university found the night sky in Tsim Sha Tsui, an urban neighborhood in southern Kowloon, Hong Kong, to be 1,200 times brighter than a normal urban city sky. Luminous pollution of this magnitude is on the rise worldwide. In a 2010 article from the Ecology and Society Journal, Hölker and others stated the use of artificial lighting increases by 20% each year, depending on the region, and noted there is an urgent need for light pollution policies that surpass energy efficiency to include humans, animals and the environment.