Light pollution is the bane of neighbors, motorists, environmentalists, and astronomers alike. While not as well-known as pollution from the air, water, and plastics, the negative effects of bad nighttime lighting are well-documented and, in many respects, just as harmful to our collective health as the other types.
Light pollution falls into three distinct categories: light trespass, glare, and skyglow.
Light trespass is misdirected illumination from one property onto another. We all know those neighbors’ outdoor lights (or streetlights) that keep us up at night as their beams stream into our bedroom windows.
Glare is also misdirected light but can be dangerous, as with oncoming headlights shining directly into your eyes on the road or when improperly shielded fixtures provide thieves a cloak of invisibility by producing pockets of glare for them to hide behind.
Skyglow is that dome of “light haze” that hangs over a city at night and can be seen for many miles in all directions. In our Northeast Corridor, skyglow spills from one urban area to the next, between Boston and Washington, DC, forming one continuous swath of light pollution.
Like other types of pollution, bad lighting has its share of negative effects: It’s a waste of energy and tax dollars; it can promote sleeplessness and suppress melatonin production in our bodies; it causes motor vehicles and pedestrian accidents; and it robs us and our children of the inherent beauty of the night sky. (When was the last time you saw the Milky Way from a Westchester vantage point?)
Light pollution has insinuated its way into our lives so thoroughly that most of us don’t even notice it until it’s pointed out to us.
“It is getting progressively worse,” says meteorologist Joe Rao, a longtime fixture of local television on both News12 Westchester and Fios1. “When I moved up here from Long Island to escape the scourge of light pollution, I could routinely see stars down to magnitude plus-5 most nights. Now, it’s more like plus-4.5. And the light dome from Westchester and New York City covers much of my southern sky. When I used to visit my Uncle Ron in Mahopac 50 years ago, the limiting magnitude was plus-6.8. That means in the last half-century, I can see about eight times fewer stars than now. Light pollution is metastasizing all across the northeast U.S., like a cancer. If this continues unchecked, 50 years from now, not much else will be visible at night other than the moon and a few of the brightest stars and planets.”
Yet, there are simple solutions that companies and homeowners can do to reverse this trend. Use only “full cutoff” fixtures, which prevent light from escaping upward into the sky or out onto your neighbor’s yard; use sensors that turn off lights when not needed; and promote better lighting in your own community by attending town-planning meetings.
Just remember with nighttime lighting that more is definitely not better.
For further information on good lighting practices, check out darksky.org.