Hourly concentrations of particulate matter rose to 6.7 times their pre-fireworks levels, according to an analysis Washington DC residents breathed in “unhealthy” air for hours after a 40-minute Independence Day fireworks show over the National Mall on Saturday night, with the country’s capital briefly recording the worst air quality of any major city in the world. The highly emitting display, which the president called “spectacular”, came as the Trump administration rolls back an unprecedented