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

The Minnesota Pollution Control Agency (MPCA) has issued an air quality alert Tuesday from 12 p.m. to 9 p.m. for ground-level ozone. This alert will impact Minnesotans in nearly two-thirds of the western part of the state. According to MPCA, sunny skies, warm temperatures and dry conditions creates an ideal environment for two types of pollutants.

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.