Washington, D.C. experiences its worst air quality of the year during the July 4 weekend after smoke from a large Independence Day fireworks display raises pollution levels across the city. Multiple outlets report that particulate matter concentrations surge for several hours following a roughly 40-minute show over the National Mall. According to monitoring and analysis cited by the reports, hourly levels of particulate pollution rise to several times pre-fireworks measurements, with concentrations reaching values considered “very unhealthy” for the general public. One outlet reports that the city briefly records the worst air quality among major cities worldwide during that period. The elevated pollution is linked to smoke from the fireworks display rather than other sources, and data are drawn from air-quality measurements released after the weekend. The reports also note public concern about health risks from breathing the polluted air for hours after the event. The fireworks show is described as large and highly visible, with the smoke affecting air quality citywide, including surrounding neighborhoods beyond the immediate National Mall area.