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WSW: Light Pollution & Why We Need Darkness For Our Health

An aerial photo of Chicago at night
Jim Richardson/International Dark-Sky Association

We know that light pollution makes it harder to see the stars - about 66 percent of people living in the United States can't see the Milky Way at night. But you might not know that light pollution also causes health problems and wastes billions of dollars in electricity every year. J. Kelly Beatty is the award-winning senior editor of Sky and Telescope Magazine. On November 4th, he’ll give a talk as part of the Kalamazoo Astronomical Society’s 80th anniversary celebration.

Darkness Prevents Cancer 

It’s easier to sleep when it’s dark, but Beatty says our bodies also need darkness to secrete something called melatonin. It’s a hormone that Beatty says has been shown to suppress cancer cells in mice:

“This was just a theory until the late 1980s, a researcher named Richard Stevens put this to a test and he found that statistically those who work night shifts - you know hospital nurses or factory workers - had a significantly higher risk for developing breast cancer in women and prostate cancer in men.”

Beatty says International Agency for Research on Cancer has also called night shift work a “probable carcinogen.”

A Waste Of Energy 

The International Dark Sky Association estimates that we waste about $3.3 billion in energy through light pollution every year. Beatty says that’s partially because a lot of lights aren’t aimed at the ground:

“A lot of businesses, especially those that are open at night use strong lighting to draw customers in. Service stations, fast food establishments are all trying to get your attention and so often they create a lot of lighting that is indiscriminant, that goes well beyond the needs for just pumping gas or whatever.”

Beatty says millions of our street lights in the United States were installed in the 1950s and have a sort of “salad bowl” design that leaks light into the sky.   

An interview with J. Kelly Beatty

Streetlights That Make It Hard To See

Believe it or not, Beatty says some lights make it harder to see while driving. He says if a streetlight isn’t designed properly, it can create glare. Beatty gives an example of how this works:

“You’re driving alone at night on a dark country road and your headlights are shining out in front of you. You know that your eyes kind of get adapting to the dark, your pupils dilate and you can see better when it’s dark after your eyes have been exposed to darkness a while. If another car is coming at you - with its high beams on or even if not - your pupils constrict and so not enough light gets into your eye to see in those dark shadows along the side of the road. And you’re momentarily kind of hindered from seeing as well until that car passes - same with streetlights.”

That’s not to say that streetlights don’t have their place. Beatty says you need streetlights in what lighting designers call “conflict zones” - like at intersections or crosswalks. He says streetlights need to be designed in a way that the light goes down and not out. 

LEDs - Energy Efficient And Deadly For Darkness

LED lights - or light emitting diodes - are the latest in energy efficiency. LEDs give out a blue light that often appears so bright that it can hurt your eyes at night. Beatty says that blue light also scatters the most easily in the atmosphere and therefore creates the most light pollution.

What You Can Do

Tips on how to prevent light pollution from J. Kelly Beatty:

  1. If you keep an outdoor security light on at night, change it so it’s triggered by a motion sensor.  
  2. When new businesses come to meetings seeking your local government’s approval, ask your leaders in your town if they would consider lighting requirements to minimize light pollution.
  3. Ask your town leaders to create bylaws that combat light pollution.
Rebecca Thiele was an environmental reporter and producer of Arts & More for WMUK. She worked at the station from 2011 to 2019.
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