Internal National Park Service documents project hazardous PM2.5 levels from 850,000 fireworks shells launched across 10 sites on the National Mall.
https://www.foxnews.com/media/washington-post-throws-cold-water-dc-fireworks-report-hazardous-air-pollution
https://www.foxnews.com/media/washington-post-throws-cold-water-dc-fireworks-report-hazardous-air-pollution