Even though the sky was cloudy in parts of the northeast and the Midwest, we suspect lingering haze in these two regions. According to the MODIS IDEA image showing the Aerosol Optical Depth (AOD), the particle concentrations are slightly higher in southern Canada, meaning north of the Great Lakes and west of New York. It seems that these particles, mixed with clouds, reached Michigan. There is also some haze north of Pennsylvania. The true color image from MODIS Terra also shows haze in the Midwest and northeast. According to the EPA AirNow PM2.5 map, the AQ is moderate in the Great Lakes region as well as in the east coast. The AQ is moderate in DC and Baltimore with PM2.5 levels reaching respectively 21 ug/m3 and 36 ug/m3.
MODIS Direct and MODIS IDEA images