Rain improves air quality
From staff reports
Thursday night's much-needed rain also markedly improved Rochester's air quality.
The city was under an air alert Wednesday and Thursday, with air quality index scores of more than 100, the threshold at which the air is considered unhealthy to sensitive people, such as the elderly and people with respiratory problems.
By 10 a.m. today, the air index was down to 67.
The index is a 24-hour average and is expected to continue falling as the day progresses.
Particulate matter was the prime pollutant behind the air alert. Raindrops cleared much of that pollution out of the air.
The pollution in Rochester was part of a large, polluted air mass covering much of the Midwest, including Minnesota.
The Twin Cities, St. Cloud and Duluth have also had air quality alerts issued this week.