Let There Be Dark
AMA Links Light Pollution to Cancer, Health Woes
Too much light isn't just ruining our ability to stargaze -- it's hurting our health, the nation's leading medical group says.By Amy Linn, 6-30-09
Glaring problems in Missoula and around the nation. Photo by Katie Brady.
The American Medical Association this month passed a resolution that recognizes a host of problems with light pollution, including health issues—such as breast cancer—that are “associated with human eye exposure to light at night.”
The AMA resolution (view it in full here) explains that
the increasing amount of light in the world, including streetlight glare and intrusive light that “trespasses” into bedroom windows and homes, is linked to higher rates of cancer and other human health problems. It reduces the production of melatonin, a hormone that helps regulate sleep cycles, and hampers the immune system, the group says. Too much night light hurts wildlife, as well.
As the AMA puts it: “Light trespass has been implicated in disruption of the human and animal circadian rhythm, and strongly suspected as an etiology of suppressed melatonin production, depressed immune systems, and increase in cancer rates such as breast cancers.” In addition, it “disrupts nocturnal animal activity and results in diminished various animal populations’ survival and health.”
Glare from things like street lights actually makes it harder for some people to see, since it causes eye pupil constriction—leading to unsafe driving conditions, especially among older people, the resolution says. In addition, the AMA estimates that “40 percent of the light emitted from standard streetlights” is glare light—or completely wasted electricity. “This contributes to excess carbon dioxide production and possibly global warming,” the group declares.
More than $10 billion could be saved if cities around the country used eco-friendly streetlights instead, the medical group concludes. One solution—adopted by an increasing number of cities—is to enact outdoor light laws and replace old-fashioned streetlights with non-glare or “fully shielded” streetlights, which shed light where it’s needed.
Missoula has taken some positive steps in this direction. The City’s Outdoor Lighting Ordinance, which went into effect January 1, 2008, aims to save energy and reduce unsafe, irritating glare from streetlights, businesses and residences.
But an admittedly unscientific recent survey shows that many homes in the city still boast over-bright lights that beam unwanted wattage into neighboring yards, homes, parks and open spaces, ending any hopes of peaceful stargazing.
Why is the AMA weighing in on this seemingly far-flung topic? Light trespassing has become a nationwide public health issue, the group says. Skies are supposed to offer solace, not annoyance, they might have added. On that note, it’s important to shed light.
For more information about light pollution, check out the International Dark Sky Association.
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