An air pollution alert has been issued for the Twin Cities and Rochester, the Minnesota Pollution Control Agency says.
The alert extends through midnight Tuesday, but the agency says that air quality is expected to improve Tuesday afternoon as wind speeds increase.
The alert says the air may have hit unhealthy levels for specific sensitive groups, including people with heart and respiratory disease, the elderly, children, and people engaged in vigorous activity.
All that melting snow and higher temperatures recently have helped trap pollutants nearer the surface, the Star Tribune reports.
Cassie McMahon, an MPCA analyst, told the newspaper, “The presence of snow melt adds extra humidity and fog, which act like a sponge to further trap the pollutants.”
Twin Cities air quality has been pretty good in the last two years, MPR reported. The metro averages about 10 air quality alerts a year, but in both 2011 and 2012, there were only four, MPR notes.
You can sign up for air pollution alerts, the state agency says: