A Light Map Could Illuminate How Street Lamps Are Part Of Pittsburgh’s Pollution Problems

Jul 6, 2020

Streetlights emitting artificial beams through neighborhoods every night could be to blame for decreasing firefly populations and a generation of young people with no concept of what the Milky Way looks like in a starry night sky. A Carnegie Mellon University professor and self-proclaimed dark-sky defender, Diane Turnshek, is working with a small team to study the problem of night time light pollution in the Pittsburgh area.

Turnshek has been gathering high resolution images of Pittsburgh at night since November. Winter is the best time to collect this data because researchers aren’t competing with tree coverage, says Turnshek, who founded the Pittsburgh chapter of the International Dark-Sky Association. 

The International Dark-Sky Association is the leading organization combating light pollution worldwide. The group has worked with several national parks to establish, “dark-sky oases,” where the nighttime sky is preserved.  

A summer class of Carnegie Mellon University students is compiling the images and data collected by Turnshek and her CMU colleague, Stephen Quick, to create a light map of Pittsburgh at night. Once completed, scientists may be able to better understand how light affects things like migration patterns and firefly populations locally.

Diane Turnshek and her CMU colleague Stephen Quick have gathered images of how light spreads out across Pittsburgh at night.
Credit Courtesy Carnegie Mellon University

They hope to complete the map before the city finishes replacing incandescent bulbs in all of its streetlights with LED lights. LEDs are more energy efficient, but Turnshek and other dark-sky defenders want cities to consider reducing lighting levels altogether when making these changes. The goal is to reduce skyglow, or artificial light directed upwards, scattering across the sky.

According to Turnshek, cities have been slow to react to the consequences of light pollution, in the same way they haven’t reacted to climate change quickly enough. “Something that is not going to impact you today – it creeps up so slowly – just isn't in that pool of worry for most people,” she said.

But even companies developing new lightbulbs have been behind on the issue, she said.

"People who manufacture lights have only just caught on that these big bright glary blue white LEDs are not really good for the nighttime ecosystem," Turnshek said.

Light pollution affects humans, too. The American Medical Association warns that it could be associated with reduced sleep duration and quality, excessive sleepiness, impaired daytime functioning and obesity. A Harvard study connected light pollution with increased risk in breast cancer for women.

The Dark-Sky Association would like to see street lights with options like automatic dimming, timers and motion sensor technology. The local chapter president, Daylon Burt, said he knows street lights will remain a part of city life, but encourages officials to rethink how much impact they have on things like crime and traffic collisions. A United Kingdom study found that part-time lighting or dimming had little effect on these incidents.

Turnshek is mindful about how dark Pittsburgh could realistically get.

“I realize that we’re not going to make the city dark enough to see the Milky Way from the triangle,” she said. “If we could just make it so that we don’t have to drive so far out of the city to see the Milk Way, I think a lot more people would be involved [in astronomical research]."

In addition to creating the light map of nighttime in Pittsburgh, Turnshek believes public education about light pollution is paramount. To that effort, she compiled an anthology called “Triangulation: Dark Skies.” Readers can parse through 21 fiction stories about how light at night affects human lives.