Nine Minnesota counties where pollution from vehicle exhaust, power plant emissions and wood burning is tracked scored well on an annual air pollution report released Wednesday by the American Lung Association.
Anoka, Dakota, Hennepin, Lyon, Olmsted, Ramsey, Scott, St. Louis and Stearns counties all received A or B grades for particle pollution in the three-year period that ended in 2013, meaning they had few or no days where state public health officials had to warn those sensitive to air pollution to cut back on outdoor activities.
But even though particle pollution is likely down in Minnesota as power plants switch from coal to natural gas and as diesel vehicles become cleaner, pollution is highly dependent on other factors out of our control, said Robert Moffitt, a spokesman for the American Lung Association in Minnesota.
That includes the weather.
"That's the one thing that can change that can really change our grades," he said. "We're producing air pollution all the time. And while we're taking steps to reduce this, it still happens every year. If we get a certain type of weather pattern, this pollution just hangs there."
And wildfires and power plant emissions hundreds or even thousands of miles away can blow into Minnesota under the right conditions, he said.
"That's one thing we really don't have that much control over," he said.
The report also looked at ozone — the summertime pollutant that forms when sunlight mixes with emissions and fumes from vehicle exhaust and smokestacks. The report showed little change from last year in ozone grades in the 14 counties where ozone is tracked.
Moffitt said the group relies on data collected by the Minnesota Pollution Control Agency's air quality monitors, but the agency's monitors for ozone or particulate matter are present only in about a fifth of the state's counties.
Air pollution is a health concern, especially for those suffering from asthma and other respiratory conditions. The report estimated that roughly 300,000 people in the 18 Minnesota counties where ozone and particle pollution are tracked suffer from asthma.
The U.S. Environmental Protection Agency is expected to finalize new federal ozone standards this fall.