Ozone is the main concern that is causing an air quality alert Monday, the Minnesota Pollution Control Agency says — but what exactly is ozone?

An air quality alert will be in effect from noon to 9 p.m. on Monday for much of the state, and dozens of counties are under a red flag warning.

The Minnesota Pollution Control Agency (MPCA) has issued an air quality alert for west central, east central, central, south central, southwest, north central, and northwest Minnesota.