Maryland Department of the Environment issued the following announcement on Feb. 5.
Did you notice hazy air the last few days, especially around urban areas? That's due to a temperature "inversion" trapping bad air near the ground. The good news is that weather conditions look to improve tomorrow to allow the inversion to break down and improve air quality. Tomorrow's forecast is for moderate air quality across Maryland. For air forecasts go to mde.maryland.gov/air.
Original source can be found here.
Source: Maryland Department of the Environment