• Why Pittsburgh Is Dimming Its Streetlights Josyana Joshua
• Artificial light at night at environmental intensities disrupts daily rhythm of the oyster Crassostrea gigas Audrey Botté, Laura Payton, Damien Tran
• LZF Lamps

Pittsburgh Dimming Its Streetlights

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.”

In-class comments:

• general strategy: face down, warmer, turn down when no one is around

• Pittsburgh Becomes a Dark Sky City

  • First city in the eastern U.S. to comply with International Dark Sky Association (IDA) standards.
  • Plans to replace streetlights with lower wattage, warm-colored LED lights.

• Light Pollution Reduction & Environmental Benefits

  • Reduces light pollution to make stars more visible.
  • Helps protect wildlife, including birds and plants, from artificial light disruptions.
  • Supports human health by improving sleep cycles and mental well-being.

• City’s Investment & Savings

  • $16 million budget allocated for replacing ~40,000 streetlight fixtures.
  • Expected to save $1 million annually in energy costs.
  • Project completion expected within 18-24 months.

• Global Dark Sky Movement

  • Pittsburgh follows cities like Tucson, Sedona, and Flagstaff.
  • Flagstaff, Arizona, was the first designated dark sky city in 2001.

• Encouraging Other Cities to Follow

  • Massachusetts and Pennsylvania considering similar legislation.
  • Washington D.C. and other cities have expressed interest.

• Addressing Safety Concerns

  • Study shows reducing street lighting does not increase crime or accidents.
  • Dark sky-compliant lights prevent glare while enhancing road and sidewalk visibility.

• Overall Benefits

  • Supports a healthier ecosystem, reduces energy waste, and improves quality of life.