Last Updated: Friday - 09/24/2010
Week of April 14, 2008
Earth's light pollution is blotting out our essential night sky
And this impacts human, animal health
By SUZANNE ELSTON
I have the most amazing poster in my office. Entitled, The Brilliant Sky: Alight by Night, it is a composite satellite picture of the Earth at night. Entire sections of North America and Europe are illuminated, and even the most remote regions of darkest Africa are speckled with dots of light, like brilliant diamonds cast on a background of black velvet.
The picture is both breathtakingly beautiful and very disturbing. For the first time in human history, the brilliant, awe-inspiring canopy of the night sky is being stolen from us by the down-to-earth glare from artificial light.
Pull the shades
In the natural night sky, we should be able to see approximately 3,500 planets and stars with the naked eye. Thanks to the interference of artificial light, in most cities a mere 50 stars are visible. An estimated 97 per cent of Canadians live under skies that are polluted by artificial light of some kind.
This phenomenon has been called light pollution, and it isn't just robbing us of our view of the stars. According to Italian astronomer Pierantonio Cinzano, 59 per cent of Canadians have lost much of their night vision. A study done by the University of Pennsylvania found that young children who sleep with a night-light were more likely to develop nearsightedness later in adolescence.
Light pollution may have even more dramatic health impacts. In the late 1980s, epidemiologist Richard Stevens made the connection between light pollution and breast cancer. He concluded that the absence of complete darkness suppresses the body's ability to produce the hormone melatonin.
This disruption in melatonin production may lead to chronic fatigue, depression, reproductive anomalies and even cancer. Other research has found that the risk of breast cancer is 50 per cent lower in blind women.
Wildlife is also being impacted by light pollution. Florida researchers have discovered that sea turtle hatchlings are being drawn toward artificial lighting along beaches, rather than to the moonlight on the water. Unable to locate a single beacon to follow, countless hatchings are crushed by passing cars or end up wandering aimlessly on the beach.
Because they steer by the stars, light pollution is also disrupting the migratory patterns of many birds, particularly around large urban areas.
While nobody's suggesting that we bump around in the dark, we need to get a lot more creative about how and when we use artificial light. Starry Night Lights, an interesting commercial website based in Utah, Colo., offers some excellent, simple suggestions.
For starters, light only what you need, when you need it. Replace that glaring porch light with a motion sensor and consider using lower-wattage bulbs outdoors. Invest in full cutoff fixtures that maximum lighting efficiency by focusing light on the ground where it's needed while shielding the night sky.
The International Dark Sky Association (IDA) has some good ideas too. For example, lighting billboards from the top down, rather than the traditional bottom up illumination that throws unnecessary light up into the sky, and installing light timers, can maximize the effectiveness of lighting, while significantly reducing energy costs.
The IDA estimates that in the U.S. alone about $1 billion is wasted annually lighting up the night sky. That's a whole lot of wasted energy and unnecessary greenhouse gas emissions.
While the idea of light pollution isn't universally known, I think intuitively we've already figured out that too much light is basically a bad thing for everyone. Maybe this is why the idea of Earth Hour is rapidly becoming such a global phenomenon. We crave the darkness and its ability to connect us with each other and the universe beyond.
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