Heatwave and record fireworks could push July Fourth air quality to unhealthy levels

Record heat and oversized Fourth of July fireworks are expected to worsen air quality in many cities: heat domes trap pollutants and boost ground-level ozone, while larger displays emit PM2.5 that can linger for hours; studies show roughly a 42% rise in these particles after shows, risking health for people with asthma, pregnancies, or the elderly, though upcoming storms could provide some relief and reduce ozone formation in some areas.