The Maryland Department of the Environment has issued a Code ORANGE Air Quality Alert on Monday, June 19th for the Maryland suburban DC region, which includes all of Montgomery County. Additional information below per the Maryland Department of the Environment:
Unhealthy for Sensitive Groups (USG) ozone concentrations remain possible Monday, compounded by persistent, though diffuse, wildfire smoke. Winds turn from the south on Monday. This will cause a recirculation of the regional airmass bringing pollution from Sunday back northward. Despite the anticipated lower emissions due to the state holiday Monday, ozone development leading to potential USG conditions for a wider area along and north of I-95 from DC to Baltimore remains possible outside of thunderstorms. As flow turns towards the east on Tuesday into Wednesday and increased chances for rain develop, air quality improves, with generally categorical Good AQI air quality expected. For current air quality conditions please check this website.