Washington DC residents breathed unhealthy air for hours after a 40-minute Independence Day fireworks show over the National Mall on Saturday night.
The nation's capital briefly logged the worst air quality of any major city worldwide, according to The Guardian.
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The display occurred as the Trump administration rolls back environmental pollution controls. Hourly concentrations of particulate matter surged to 6.7 times pre-fireworks levels across the city.
An analysis from Clarity Movement, using a network of 26 air quality sensors in partnership with the local department of energy and environment, confirmed the spike.
Every sensor reached levels the Environmental Protection Agency classifies as unhealthy for sensitive groups.
Fine particulate matter peaked at 4 a. m.
Sunday, roughly five hours after the spectacle ended.
Pollution remained elevated for about five hours after the peak, prompting local officials to issue a Code Red alert.
"Outdoor air quality is unhealthy for seniors, kids, people with medical conditions," the alert said. "General public may experience health issues.
Limit time outside."
Researchers noted the southwest region of Washington DC faced the heaviest pollution.
This localized spike was attributed to proximity to a launch site in West Potomac Park and overnight meteorological conditions that trapped smoke.
David Lu, CEO and co-founder of Clarity Movement, stated the heavily polluted air mass likely drifted into Arlington, Virginia.
"Unfortunately, we don't have sensors there to confirm it," he said. "That's exactly why expanding real-time air quality monitoring matters.
