"Fireworks release tiny particles that can irritate lungs and trigger asthma attacks, along with gases like carbon monoxide and sulfur dioxide..."

"... and sulfur dioxide and metals including aluminum, manganese and cadmium, according to the American Lung Association. Even Freedom 250, the Trump-backed group that helped organize the event, acknowledged on its website that 'air quality will decline' and visibility 'may become compromised.' It advised children and older people to avoid extended time outdoors and advised residents to keep windows closed and to use air filters. 'It’s probably going to be incredibly hot and adding a firework show is just going to compound the air quality that’s already destined to be poor,' said Panagis Galiatsatos, a pulmonary physician.... He encouraged people with respiratory conditions like asthma to stay indoors and watch the spectacle on TV. 'Sometimes we need to just be mindful of safety versus grandiosity'.... Dogs tremble. They drool. They try to hide by cramming themselves into spaces that are too small. They have accidents indoors and tear up clothes or furniture...."

From "Bombs Bursting in Air Means Hours of Smoke and Confused Dogs in D.C./Organizers want the July 4 fireworks in the nation’s capital to break the world record. But the fun will also come with air pollution and possibly headaches for pet owners and zoo keepers" (NYT).