The Importance Of Reducing Light Pollution

The Milky Way can be seen from White Sands in New Mexico at night. Light pollution from El Paso can also be seen (orange area to left of image). Photo by Jennifer Sensiba.

Growing up in the Southwest, I didn’t realize how fortunate I was. I’ve never lived more than a 20-minute drive from a place where you can see the Milky Way. My family regularly took me to nearby mountains and wilderness areas where it was profoundly dark, and the stars seemed to almost fill the whole night sky, in a broad variety of colors.

I didn’t know that many people only rarely see what I regularly saw, and that some people go their whole lives without seeing the Milky Way in the night sky. I also didn’t know that light pollution could affect our mental and physical health in profound ways.

While light pollution is a topic we’ve covered here before, it’s something that doesn’t get enough attention. After reading an op-ed in the New York Times over the weekend by Dr. Kelsey Johnson, an astrophysicist, I thought it would be a good idea to give us all a reminder of the importance of reducing light pollution.

The Problem of Light Pollution

If you look at DarkSiteFinder.com’s light pollution map, it’s not hard to see just how widespread the problem is. As Dr. Johnson points out, almost everywhere in the United States east of the Mississippi is heavily affected, and a growing portion of the western US is likewise growing blind to the stars.

It’s worth looking at at the map yourself to zoom in and see what it’s like where you live. From my experience in the Southwest, and comparing it to this map, it’s possible to see the Milky Way in places that are dark blue, grey, or black on the map. In light blue areas, it’s sometimes possible to see it if you’re in an area where terrain blocks enough of the light pollution.

A screenshot of DarkSiteFinder’s light pollution map.

At best, heavy light pollution deprives us of our ability to see the stars. Aside from the obvious loss of aesthetics or recreational opportunities, it could present a more important cultural loss. Dr. Johnson points out:

“I think there is even an existential cost. A dark night sky, unpolluted by artificial light and thousands of artificial satellites, serves as a visceral reminder that we are part of something unfathomably large, that our petty differences on this tiny speck of a planet are ultimately insignificant. In the face of the universe, human arrogance is absurd.”

Unfortunately, the problems don’t stop at the philosophical. There is real damage to health and nature when we don’t get dark skies at night.

For humans, not getting enough darkness at night is associated with cancer of all kinds. One study concludes, “Artificial light at night is significantly correlated for all forms of cancer as well as lung, breast, colorectal, and prostate cancers individually. Immediate measures should be taken to limit artificial light at night in the main cities around the world and also inside houses.”

The International Dark Sky Association (IDA) says that light pollution can increase risks for obesity, depression, sleep disorders, diabetes, and more. How? By disrupting our internal clocks, throwing off our melatonin levels, and disrupting a variety of other hormones in the body.

Additionally, excess light can increase crime and reduce human safety, contrary to popular belief.

Like humans, nature is also affected. Animals of all kinds need dark nights to regulate their chemistries, find prey, and navigate. The ways in which they can be affected are many, and you can learn a lot more at the IDA’s website.

Finally, energy waste is an issue pointed out by both Dr. Johnson and the IDA. Generating all of the extra light at night isn’t free, even with efficient LED lighting.

What You Can Do About Light Pollution

A screenshot of DarkSiteFinder’s light pollution map, showing Tucson, Arizona’s light pollution on the left and El Paso, Texas’ light pollution on the right.

Fortunately, light pollution isn’t a given. It’s something you can do something about. Tucson, Arizona shows us some of what we can do. Not all cities, even of comparable size, are equal in their light pollution.

The IDA gives a good number of tips to help reduce light pollution:

• Carefully choose outdoor lighting.
• Push for outdoor lighting ordinances in your area.
• Politely approach neighbors light polluting your neighborhood, or light trespassing.
• Approach your local government when there are polluting or trespassing street lights.
• Get involved and spread the word.