DARK SKY CITIES
Why Pittsburgh Is Dimming Its Streetlights
by Josyana Joshua / December 14, 2021
“The world’s urbanization has made it increasingly difficult to see the stars in city skies, but that may be changing — at least in Pittsburgh. The Pennsylvania city announced in August it will become a dark sky city starting in 2022, meaning that it will switch to lower wattage LED bulbs and add shades along bridges, roads and other public areas. It’s the first city in the eastern part of the U.S. to adopt such policies but it joins other cities, including Tucson and Sedona in Arizona, and Fulda in Germany, in their efforts to reduce light pollution and increase energy efficiency. “It’s a relatively easy fix that all local governments could take on,” said Grant Ervin, Pittsburgh’s chief resilience officer and spearhead of the dark sky ordinance. “It’s one of the tools that local governments have an ability to regulate and install as standard.” Pittsburgh has budgeted $16 million for the streetlight project and estimates it will save $1 million in energy costs, Ervin said. The city will switch lightbulbs in about 40,000 fixtures on the street and in public buildings to LEDs that emit less blue light, or short wavelengths that can have a detrimental impact on plants, insects and other wildlife. It aims to complete the project within 18 to 24 months, but expects to see the benefits of a dark sky even earlier.
“Aerial view of Phipps Conservatory and Botanical Gardens in Pittsburgh 2019”
Pittsburgh will be the first city in the world to follow the International Dark Sky Association’s new values-centered outdoor lighting, which means it will follow the group’s more comprehensive suggestions surrounding wattage and color temperature as well as when and how to keep lights on. The nonprofit group’s mission is to preserve the night sky, but also to prevent other consequences of light pollution. Since much of the environment’s changes are spurred by the sun, excess artificial light can disrupt bird migration patterns or cause trees to turn green too early. It can also confuse the natural 24 hour day/night cycle for humans — a darker sky has been found to have positive effects on mental health, with stargazing and less blue light playing a part. “All life on the planet has a cue that says depending on how much light there is at what time of year that it’s time to do something,” said Diane Turnshek, a lecturer at Carnegie Mellon University who teaches astronomy and consulted with Pittsburgh to establish its dark sky ordinance. “So when you have light pollution you’re changing the nighttime ecosystem in such a way that it’s disruptive.”
Some cities participate in smaller dark sky initiatives. Lights Out Philly and Lights Out Pittsburgh turn off and/or block any external and internal lights at night during bird migration season, since birds are often attracted to the light and end up flying into buildings. Turnshek said the school started turning off lights from midnight to six a.m. during bird migration season. But after they noticed how much money they were saving, they decided to keep them off indefinitely. Turnshek says some eastern U.S. cities, including Washington, D.C., have reached out to her since Pittsburgh made its announcement. Massachusetts has a bill in the House and Senate to make the state dark sky friendly, and Pennsylvania state Senator Carolyn Comitta of Chester County, Pennsylvania, is trying to bring legislation to make the state dark sky compliant as well.
And other states have smaller light pollution laws. There has been hesitancy to adopt dark sky policies because extra lighting makes people feel safer, Turnshek said. But according to a 2015 study published in the Journal of Epidemiology and Community Health, reductions in street lighting in England and Wales had no impact on road accidents or crime rates. The dark sky compliant lights also prevent glare in places that aren’t intended to be lit, and focus the light better, further illuminating roads and sidewalks, Ervin said. Turnshek said many people are still unaware of the benefits of becoming dark sky compliant, but the advantages are becoming more clear. “It’s better for the environment, if you change to these low wattage and low color temperature lights. It’s better for people’ health, better stars, and just across the board they’re better,” Turnshek said.”
Skyglow: The night sky you can’t see
by Gavin Heffernan + Harun Mehmedinovic / May 28, 2017
“When was the last time you looked up at the night sky and glimpsed the Milky Way? Last night? A year ago? Never? Some 80% of North Americans can no longer see the galaxy due to light pollution, or skyglow. Light pollution causes a profound ecological disruption that affects human health, alters animal migratory patterns and obstructs astronomical research. Recent findings even suggest higher breast cancer rates may result from artificial day conditions created by over-lighted cities and the consequent suppression of nocturnal melatonin production. It’s estimated that one third of the world’s population lives under light-polluted skies, a situation worsening dramatically with aggressive urban expansion.
To bring attention to the problem, we traveled across the continent using long exposure DSLR photography to capture the cosmos from North America’s endangered “dark sky” locations. Despite its immense population, we still found some of the best shots in our own backyard of Southern California. Each photo was exposed for 25 seconds, allowing galactic details to flood in — far more than can be seen with the naked eye. The psychedelic “star trails” effect in many of the pictures was created by tracking the rotation of the Earth’s axis over several hours as our cameras fired continuously, operated by remote controls known as intervalometers. Night isn’t just a darker version of day, it’s our chance to see the universe — or it was once, and could be again if we understood light pollution as the environmental tragedy it really is.”