MARSHALL — An air quality alert for southern Minnesota is going into effect Tuesday afternoon, the Minnesota Pollution Control Agency said. The alert affects an area covering the southern half of the state, from Marshall all the way to St. Cloud, the Mille Lacs tribal nation, and the Twin Cities metro area, the MPCA said.

On Tuesday, ground-level ozone is expected to be high in the afternoon hours, and air quality will be unhealthy for sensitive groups. In a news release, the MPCA urged the public to take precautions, including avoiding local sources of air pollution like busy roads and wood fires, and possibly limiting outdoor physical activity.

A combination of factors like air pollution and warm temperatures figured into the air quality alert, the MPCA said. Southerly winds are bringing air pollutants into Minnesota. The pollutants react with sunlight, warm temperatures and low humidity to produce ground-level ozone. Unhealthy ozone levels can aggravate lung diseases like asthma, emphysema, and COPD, the MPCA said.

Ozone levels in southern Minnesota will be highest during the afternoon and early evening hours, when there is more sunshine and higher temperatures, the MPCA said. The air quality alert will be in effect from noon through 8 p.m. Tuesday.