Code Yellow (Moderate) levels of PM 2.5 were seen in the Rocky Mountain States, the Southern Plains states, and the Mississippi Valley(AirNow, top left). There were also Code Orange (Unsafe for Sensitive Groups) levels seen in Idaho, Montana, and Oklahoma. There was smoke seen in the Southern Plains States and in Florida, as seen in NOAA's smoke map, top right. The smoke was most likely the cause of the elevated levels of PM 2.5 seen in these regions. NASA's Terra MODIS images captured some of the smoke seen in the Plains States mixed in with some cloud coverage (bottom left). Sulfate may have also played a role in the elevated pollutants, as there was a good amount of sulfate seen across the East coast and the Plains States today (NRL, bottom right).