In the last twelve hours, a regional PM 2.5 air pollution episode has started in the PA-MD-North VA-South NJ area.
The air pollution episode involves widespread Code Orange PM 2.5 air pollution. PM 2.5 are inhalable particles and aerosols that are 2.5 microns or smaller in diameter.
More below....
As of 2 PM on Saturday, U.S. EPA's AIRNOW site imagery indicates a significant regional PM 2.5 episode in the area mentioned:
http://www.airnow.gov/...
Same area since midnight:
http://www.airnow.gov/...
This condition appears to be formed on the back
end of a high pressure ridge extending into the mid-atlantic
area. This may be weakening so there may be some improvement moving from west towards the east in the area.
Washington DC to Philadelphia area detail PM 2.5 monitor data:
http://www.airnow.gov/...
For haze cams in the Northeast...see:
http://www.hazecam.net