Have you seen overhead clouds at night glowing with strange pink or orange colors? This is wasted light reflecting off the water particles that form clouds; light pollution which causes an atmospheric phenomenon known as sky glow.
The reason why we see so few stars at night in big cities is that city lights make the sky very bright. Nightime light intensities 10,000 times dimmer than the sun, but 25 times brighter than the full moon have been reported. (1) Much of the light pollution across most of Earth is unnecessary, and is a result of poor lighting fixtures and poor lighting design.
The term light pollution is relatively new, but the problem is so widespread that scientists rank light pollution alongside issues such as air, water, and soil pollution, carbon dioxide emissions, and noise. Scientists recently reported that city lights diminish the nighttime cleansing of the atmosphere, and this could have an influence on what happens the next day in terms of air pollution. Nitrate (NO3) radicals typically help cleanse the nightime atmosphere by breaking down certain air pollutants. During the day, sunlight quickly destroys nitrate which is at low concentrations. However, the nighttime glow of the LA Basin is intense enough to do some damage, reducing the nighttime cleansing activity of nitrate by as much as 7 percent. That, in turn, could leave more pollutants in the air overnight—as much as 5 percent more nitrogen dioxide (NO2), in particular. Nitrogen dioxide is a key ingredient in the daytime formation of ozone, a regulated pollutant that can harm people’s lungs as well as crops and ecosystems. Researchers conclude, “Many cities are really close to their regulatory limits for ozone, so even a small effect like this could be important for those regulations.” (1)
Ron Chepesiuk reports, “Two-thirds of the US population and more than one-half of the European population have already lost the ability to see the Milky Way with the naked eye. Moreover, 63% of the world population and 99% of the population of the European Union and the United States (excluding Alaska and Hawaii) live in areas where the night sky is brighter than the threshold for light-polluted status set by the International Astronomical Union.” (2)
On ordinary nights with electric power, the bright sky surrounding cities at night can extend some 150 miles for population centers. (3) With Los Angeles, sky glow is visible from an airplane 200 miles away. (2)
Too much artificial light at night disrupts people’s natural daily rhythm, which results in a variety of health problems. The lack of darkness at night affects the behavior of plants and animals, disrupting the natural cycles of light and darkness. Researchers have noticed that diurnal birds can increasingly be heard singing at night, birds’ migration routes have altered, and insects’ activity patterns have been disrupted. (4)
“In Florida’s Sarasota County, the problem of light pollution is particularly acute because this area of the Florida coast is a significant sea turtle nesting zone, where a number of threatened or endangered species lay their eggs every season from May through October. Adult females and turtle hatchlings alike are affected by artificial nighttime light, which interferes with their ability to navigate to and from nesting areas. Several methods for saving the turtles were tried, including caging and artificial hatcheries, but none of these efforts worked as well as mandatory lighting codes”, notes Luz Claudio. (3)
Migrating birds also are particularly affected by bright and blinking lights, which confuse them and cause them to crash into buildings and communication towers as they fly their nighttime patterns. (3) “The 24-hour day/night cycle, known as the circadian clock, affects physiologic processes in almost all organisms. These processes include brain wave patterns, hormone production, cell regulation, and other biologic activities. Disruption of the circadian clock is linked to several medical disorders in humans, including depression, insomnia, cardiovascular disease, and cancer. Difficulties with adjusting the circadian clock can lead to a number of sleep disorders, including shift-work sleep disorder, which affects people who rotate shifts or work at night, and delayed sleep-phase syndrome, in which people tend to fall asleep very late at night and have difficulty waking up in time for work, school, or social engagements.” (2)
In an effort to assess the magnitude of light pollution, a comprehensive World Atlas of Artificial Night Sky Brightness was produced in 2001 by researchers at the University of Padua, Italy, and the National Oceanic and Atmospheric Administration (NOAA). With efforts like this, light pollution is rapidly gaining recognition as a global economic issue. Although the problem is most pronounced among developed industrialized nations, it is also responsible for squandering the limited resources of poor and developing nations that can least afford the waste. (5)
It’s estimated that each year the total value of wasted light in the United States alone is equal to about $1 billion. A dramatic illustration of this problem occurs whenever one flies over a metropolitan area at night. While the thousands of tiny lights below might look impressive, all the light visible from an airplane window represents wasted illumination and energy. (5)
How do you minimize light pollution? One approach is to shield nighttime lighting and direct it appropriately so that all the light is directed down to the ground where it is needed rather than up into the sky. By doing this, lights with lower wattage can be used and a significant amount of energy and money saved. Another solution is to simply reduce the number and brightness of lights. Lastly, replacing inefficient fixtures with modern energy-efficient (and shielded) models, as well as using motion sensors and timers, can all help to save energy and reduce wasted light (5)
The establishment of dark sky parks and reserves is one measure aiming to combat light pollution. Like classic nature reserves, dark sky parks have not only ecological, but also educational roles to play. This is a relatively new idea; the first such park was established in Canada in 1999. Today there are 20 such projects worldwide, mostly in North America. In Europe, the establishment of the Izera Dark Sky Park, which straddles the Polish-Czech border is one of Europe’s first ‘darkness reserves’. (4)
Some regions are protected without any reference to an observatory or park:
Regions of Coquimbo, Atacama, and Antofagasta in northern Chile.
The island of LaPalma of the Canary Island.
Mauna Kea on the Big Island of Hawaii (this is arguably the darkest of any major observatory site.)
Mauna Kea towers almost fourteen thousand feet above sea level and is home to the greatest collection of large telescopes on the earth. In several communities around the base of the mountain, the types of allowed nighttime lights have been restricted to keep the skies dark at the mountaintop—assuring that this site will remain one of the best in the world for astronomical research. This approach has also been successful in communities such as Tucson, Arizona, where the nearby Kitt Peak Observatory has been in operation since the late 1960s. (6)
Lighting energy accounts for about four to five million barrels of oil (equivalent) per day. Energy audit data demonstrates that about 30 to 60 percent of energy consumed in lighting is unneeded or gratuitous. (7) Think about this the next time you’re in a big city and notice all the skyscrapers with lights on all floors even though the workforce is gone.
References
“Night Lights,” ESRL Quarterly, Winter 2011, Page 1
Ron Chepesuik, “Missing the Dark: Health Effects of Light Pollution,” Environmental Health Perspectives, 117, January 2009
Luz Claudio, “Switch On the Night: Policies For Smarter Lighting,” Environmental Health Perspectives, 117, January 2009
Ewa Deren, “Preserving Darkness,” Polish Science, 38, 14, November 2010
“Light Pollution,” [url=http://www.pollutionissues.com/Ho-Li/Light-Pollution.html]http://www.pollutionissues.com/Ho-Li/Light-Pollution.html[/url], accessed December 1, 2010
“Protection of Hawaii’s Observatories From Light Pollution,” Institute for Astronomy, University of Hawaii
“Light Pollution,” [url=http://en.wikipedia.org/wiki/light-pollution]http://en.wikipedia.org/wiki/light-pollution[/url], accessed December 1, 2010
