How an effort to combat light pollution with LEDS failed

A county in Washington State decided to replace all of its county-owned streetlights with LEDs, at least partially in an effort to combat light pollution. New research shows that they actually made the light pollution worse.

The retrofit process took place between 2018 and 2019, and Dr. Hung and her team took measurements both before the install and after all of the new lights were in place. The sky actually got brighter in the county after the LEDs were installed.

Despite actually making light pollution slightly worse, the LED retrofit can still be considered a success for its other two goals—decreasing energy consumption and cost. The LEDs are undeniably more energy-efficient than the high-pressure sodium lamps they replaced, and will last much longer, decreasing their overall cost to the county.