How cities are cutting down on light pollution

As cities invest in technology upgrades, they have an opportunity to reduce light pollution, which impacts 99% of people in the U.S. and Europe.

Why it matters: Pollution is typically thought of as air, water and soil contamination, but light pollution — including from streetlights that cast excessive light — also harms the environment, human health and the stability of the global ecosystem.

The impact: Light pollution is associated with sleep deprivation, impaired daytime functioning and obesity.

• It has also been found to disrupt the migratory and breeding patterns of birds, sea turtles and numerous other species.

Reality check: Unlike air or water pollution, however, light pollution is easily reversible.

What's happening: Cities are making strategic investments, including updating streetlights to reduce the span of light and to replace existing infrastructure with LED technology, which is environmentally friendly and offers cost savings.

• Pittsburgh is partnering with Carnegie Mellon University to retrofit the city’s streetlights with LED lights that mimic natural light.
• Middletown, Ohio, recently announced a plan to convert 2,000 streetlight heads to LED, which will save the city $359,000 in energy and maintenance costs each year.

In the process of LED conversion, some municipalities, like Wilmington, Del., have also explored retrofitting streetlight fixtures with sensor technology that could collect air quality, weather and noise pollution data.

But, but, but: LED deployment is not the end-all, be-all solution. At one point, Davis, Calif., inadvertently over-lit the city with LED lights.

• And, as is the case with any urban sensor technology, any data collected by new streetlight technology will need to be anonymized and secure.

What to watch: In addition to LED deployment, cities are exploring other tactics to encourage reduce light pollution and encourage energy efficiency.

• Asheville, N.C., has an ordinance that limits restaurants' outdoor lighting.
• Hollywood, Fla., has an ordinance requiring oceanfront properties to dim their lights at night to avoid interfering with sea turtle mating and migration patterns.

Karen Lightman is executive director of Metro21: Smart Cities Institute at Carnegie Mellon University.