The Maryland Department of the Environment has issued a Code ORANGE Air Quality Alert Sunday for the Maryland suburban DC region, which includes central and SE portions of Montgomery County (Gaithersburg, Rockville, Bethesda, Potomac, Silver Spring, etc.).
A Code Orange Air Quality Alert means that air pollution concentrations within the region may become unhealthy for sensitive groups. Sensitive groups include children, people suffering from asthma, heart disease or other lung diseases and the elderly. The effects of air pollution can be minimized by avoiding strenuous activity or exercise outdoors. Additional info below.
Per the Maryland Dept. of the Environment: Unhealthy for Sensitive Groups (USG) ozone concentrations are possible Sunday and Monday, compounded by persistent, though diffuse, wildfire smoke. Despite lower emissions Sunday, a combination of aged wildfire smoke, intense sun, and light northwest winds will foster ozone pushing towards the lower USG categorical forecast Sunday for areas southeast of DC. Development of surface inversions Sunday morning will trap lingering smoke in the region, causing fine particle concentrations to persist overnight into Sunday. The morning inversion will also trap sufficient ozone precursors to allow 8-hour ozone concentrations southeast of DC to flirt with threshold USG. Compounding impacts due to persistent elevated fine particles in the diffuse smoke will further degrade air quality in the USG region and cause regional AQI in the mid to upper Moderate range. Stout Bay breezes will also return urban emissions around Baltimore Sunday afternoon, however current thinking is ozone concentrations within the Bay breezes will not be sufficient for USG 8-hour averages there. On Monday, winds turn from the south. This will cause a recirculation of the local 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, improved air quality develops, with generally Good air quality to the east, with low-end Moderate over the western half of the state. Monitor the Maryland air quality website for updates as well as for current air quality conditions. Featured photo courtesy of the National Weather Service