Detroit has been ranked as having the worst air quality in the world on Thursday after Canadian wildfire smoke blanketed Michigan.

As of 10 a.m. on Saturday, June 17, the EPA’s AirNow website had Detroit listed as “unhealthy” with a PM2.5. The air quality is expected to improve to “unhealthy for sensitive groups” later in the day and reach “moderate” on Sunday.

This chart uses data from AirNow to track air quality in select Michigan cities and regions. Updated daily.

DETROIT Its a hot holiday weekend in Michigan, but air quality for much of the state is at a moderate level of concern. The U.S. AQI (Air Quality Index) is how the EPA reports air quality. The higher the AQI value, the greater the level of air pollution and the greater the health concern. For example, an AQI value of 50 or below represents good air quality, while an AQI value over 300 represents hazardous air quality. Air quality is acceptable.