Air quality across Washington, DC, and northern Virginia is expected to deteriorate to “very unhealthy” levels on Saturday as the region faces extreme heat ahead of Fourth of July celebrations.
The US Air Quality Index also forecast “unhealthy” conditions in parts of suburban Maryland, just outside the nation’s capital.
Montgomery County Health Officer Dr Kisha Davis warned that soaring temperatures, combined with fireworks, are likely to worsen air pollution throughout the day.
“If you can be inside, be inside,” Davis told CNN, comparing the day’s air quality to “running a marathon while smoking a cigarette.”
As of 9am ET (1300 GMT), air quality in Washington, northern Virginia and suburban Maryland remained at “moderate” levels.
The Trump administration hopes to set a Guinness World Record for the largest fireworks display, with nearly 850,000 shells scheduled to be launched from 10 locations around the Lincoln Memorial Reflecting Pool, the Potomac River and West Potomac Park.