A study of Kalispell’s air quality last winter suggests that all those wood-burning stoves being stoked up now as temperatures drop will bring another round of hazy days to the Flathead.

“It was nothing we didn’t expect,” said Wendee Jacobs, a sanitarian in the Flathead City-County Health Department who deals with health issues related to air quality.

Last winter the University of Montana’s Center for Environmental Health Sciences took air samples every six days from November through February.

Results released at the end of August showed that 69 percent of the PM-2.5 particles and smaller — those that are so small they don’t get filtered out in the lungs and can pass through to cause problems deep in the lungs and in the heart — come from residential wood combustion.

“It shows us where we need to target our resources” to mitigate health concerns, Jacobs said. “Since we’re not exceeding the standard yet, we just need to work on the right places.”

Environmental Protection Agency standards vary with time of day and year and other factors, she said, so pinning down a hard-and-fast standard is complex.

But the University of Montana study determined the average 24-hour concentration was 10.1 micrograms per cubic meter.

The highest concentration was measured on Feb. 6, 2009.

Since it was in the winter when open burning is banned, it’s pretty certain that wood stoves were the biggest contributor. Other sources could have been smoke from prescribed fires, residential burning of biomass waste and small industrial sources, the study said.

Ammonium nitrate came in a distant second, contributing 16 percent of the particulates. It’s a combination of ammonia from things such as decaying livestock waste, use of chemical fertilizers, sewer plant emissions, biological processes in soils and some combustion; and oxides of nitrogen that come largely from heavy-duty vehicle emissions.

There were other components — diesel was 6 percent, sulfate was 4 percent, street sand was 2 percent and automobiles were just under 1 percent.

The study’s findings are not a reason for concern.

But people with breathing issues or heart problems could be affected. Learn more about the health risks and actions to take by going to the EPA’s Web site, www.epa.gov

The Montana Department of Environmental Quality also posts nearly real-time values for air quality in Kalispell, Whitefish, Libby and other cities across the state.

Go to www.deq.mt.gov and click on the Air Quality Info icon.

“If you have health issues, give us a call because we’d like to help you,” Jacobs said.

Call her at 751-8130. She said the department also will update its Web site regularly. Visit www.flatheadhealth.org

Reporter Nancy Kimball can be reached at 758-4483 or by e-mail at nkimball@dailyinterlake.com