If you look at Oklahoma's air quality index, it reports that the air is good and moderate in some areas. Health experts say that's inaccurate, for the reason that it doesn't account for the particles that come from wildfires because they're too small.

Unusually vicious and damaging weather across multiple U.S. states spawned violent tornadoes, blinding dust storms, and fast-moving wildfires over the weekend, leaving at least 39 people dead.

Cleanup and recovery operations are underway across the central and eastern U.S. in the wake of a powerful storm system that swept across the nation, producing violent tornadoes, a dust storm, wildfires and blizzard conditions that have left at least 42 people dead.