Potentially harmful nighttime light varies by Ward in Washington DC, new DarkSky DC study shows
Environmental group finds uneven progress
following installation of LED street lights
For immediate release
August 26, 2026
Residents of Wards 7 and 8 are exposed to more potentially harmful outdoor nighttime light than those who live elsewhere in the District of Columbia, according to a new report on D.C.'s LED street light conversion project.
The disparity among wards is concerning because research links excessive outdoor light at night to numerous serious health problems, including cancer, cardiovascular disease, obesity, and diabetes, according to DarkSky DC, the local chapter of DarkSky International.
The D.C. Department of Transportation boosted light levels in Wards 7 and 8 after numerous residents of the two wards requested brighter lighting. The preference for more light suggests the need to increase public awareness of the negative effects of excessive outdoor light at night, DarkSky DC concludes in its report.
DarkSky DC surveyed the brightness of the District's new LED street lights at 32 sites across the city. The group found that installation of LEDs reduced excessive lighting that previously had been up to seven times brighter than what's considered sufficient for traffic safety.
The survey revealed a striking difference, however, among wards. Average street-light intensity in Wards 7 and 8 was 238% of the recommended minimum for traffic safety. In the District's six other wards, the average light level was lower, but still 181% of the recommended minimum.
A quarter of residents in Wards 7 and 8 fall below the poverty line, raising the issue of environmental justice. Some researchers have suggested that disturbed sleep from light pollution may be one cause of health inequities.
"We commend DDOT for taking advantage of LED technology that allows dimming, but carefully timed dimming in overnight hours should be considered more broadly across the city," said Wayne Savage of DarkSky DC. "Artificial light at night is a pollutant that threatens the health of all District residents when used in excess."
DarkSky DC calls for DDOT to identify a neighborhood where residents favor reduced lighting and launch a pilot project of light curfews – dimming or shutting off street lights during off-peak hours when vehicle and pedestrian traffic are negligible. The group also wants DDOT to address any remaining street light "hot spots" and calls for the D.C. Department of Health to warn residents that exposure to artificial light at night is a risk factor for negative health outcomes.
Please find the full report on the street-light survey here:
REPORT: Potentially harmful nighttime light varies by ward in DC, new study shows
Please find a copy of this press release here:
PRESS RELEASE: Potentially harmful nighttime light varies by ward in DC, new study shows
For more information, please contact:
Wayne Savage
202-509-3073
