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Ozone season starts March 1

Ozone season begins March 1 and runs through the end of October.  Air Quality Division meteorologists at the Michigan Department of Environment, Great Lakes, and Energy (EGLE) keep their eyes on the skies year-round and continue to forecast air quality related issues. When weather conditions may cause air to be unhealthy for some individuals, our meteorologists will issue advisories or alerts. On these days, people are encouraged to change their activities to minimize their exposure.

Graphic showing ozone formation process

Ozone formation process. 


Action days are called when levels of ozone or particulate matter put people at risk. During ozone season, high levels of ozone near the ground can have harmful effects for sensitive individuals.

Meteorologists will issue an Air Quality Advisory when levels of pollutants may be “unhealthy for sensitive groups”. These levels are shown as “orange” on the Air Quality Index or AQI.  An Air Quality Alert will be issued when levels are expected to be in the “unhealthy (red)”, “very unhealthy (purple)”, or “hazardous (maroon)” levels. At these levels, air quality is more likely to impact even healthy individuals. It is important to know how to protect yourself and your loved ones when air quality is unhealthy. 

Sign up to receive notices about air quality at or visit to see how your air quality is today.

Learn more about air quality on the EGLE webpage.