I usually don't read “science” opinion pieces written by non-scientists. An e-mail from subscriber Gardner Howe, however, contained a link to an article I find difficult to ignore. Gardner sent some nice comments about my article “Can we win the war against light pollution?” which appears in the February 2009 issue of Astronomy. He also sent a link to the online article “Let There Be Dark?” posted Wednesday, December 31, 2008. In the article, columnist Steven Milloy wrote the following. I selected parts to reprint here:
In a commentary in Nature magazine (Jan. 1) presaging the 2009 International Year of Astronomy, astronomer Malcolm Smith says that it’s time for cities to “turn off the lights” so we can better see the Milky Way, conserve energy, protect wildlife and benefit human health .
… Odder still is Smith’s subsequent statement that, “Our relationship with artificial light is complicated and changing. Humans innately fear the darkness and modern society relies on light as a security measure, even though there is no evidence that controlling light wastage increases crime levels.”
Moving past the term “controlling light wastage,” which seems to be little more than a euphemism for darker city streets, plenty of data link dim urban areas with higher crime rates. A 2004 study in the Journal of British Criminology, for example, studied 13 U.S. and British cities and concluded that improved street lighting, on average, was associated with a 20 percent decrease in crime. In contrast, I could find no data linking the inability to see the Milky Way with any sort of harm to anyone.
No astronomer I know is suggesting a return to the Dark Ages. We all love our computers, televisions, and refrigerators too much for that. Besides, without headlights, we’d have to walk to our dark-sky sites. No way!
Here’s the problem with Milloy’s argument. He equates “dark sky” with “dark ground.” Astronomers aren’t suggesting we turn off necessary lights — we simply want them properly shielded.
Shielding lights accomplishes several things: First, it darkens the sky. Ok, that’s good for astronomers. We thank you. But practical reasons also exist for shielding lights. For example, a well-designed fixture reduces glare, which allows people to see their surroundings better. And by directing light downward only (where it’s needed), manufacturers can reduce the total output of the fixture. The result? We save money. Proper design also has an immediate impact on safety issues.
First, the glare of streetlights can make driving dangerous. I’ve driven through cities where faux-antique lights pose a real hazard. Because such lights shine directly into drivers’ eyes — rather than onto the ground where the light would do the most good — pedestrians are at risk.
Also, at night, our eyes’ pupils dilate, naturally adjusting to a lower illumination level. A driver suddenly coming upon a brilliantly lit mall or service station may be at a visual disadvantage until his or her eyes readjust.
Home safety as well as security for those out at night, likewise, don’t depend on how much illumination you use to light the street, house, or yard, but how well you use it. Your ability to see someone skulking around your house or your neighbor’s goes up as you reduce glare. Simply adding more lights won’t help, and it could make the situation worse.