The Northern half of Utah continues to experience unhealthy concentrations of PM2.5. For a few days already, the state has experienced the worst air quality in the US. The state authorities are prohibiting wood burning and urging people to limit driving. Hourly ozone levels also reached code orange in Utah for a few hours.
On the AIRNow animation below (left) you can see Utah's conditions compared to the rest of the US. Other regions such as the Midwest and the Northwest Pacific experience moderate levels of particulate matter today. On the right hand side is a table from AIRNow (modified) showing the forecast conditions for today and tomorrow, as well as the current conditions as of 6pm MST.
Below is today's MODIS Aqua true color and AOD retrievals overlaid with the current AQI. Extensive cloud and snow coverage hinders AOD retrievals in many regions.