It was a very quiet day in terms of air quality in the US today. Most of the country enjoyed good air quality, with only a few regions experiencing moderate levels of PM2.5, such as Pennsylvania, Kentucky, West Virginia and some isolated regions in the Northwestern states, as can be seen in the AIRNow animation below. There were no significant areas of fire or smoke reported by the HMS team either.
In terms of satellite imagery, clouds were covering most of the US as can be seen in MODIS Aqua RGB/AOD image below. You can also see Hurricane Sandy in the bottom right portion of the image, just north from the Bahamas. The streak of clouds you see across the Midwest all the way down to the South is associated with the cold front coming from the West. This is the front that you've been hearing about in the news that could be merging with Sandy this week to create the so-called "Perfect Storm".