Breathe easy, Whitefish. State regulators said Monday the city is in compliance with national air quality standards, nearly three decades after it was marked for high levels of coarse particulate matter from dusty roads, parking lots and alleys.

The Montana Department of Environmental Quality now is asking the U.S. Environmental Protection Agency to certify that Whitefish meets federal Clean Air Act requirements.

"For a number of reasons, businesses often prefer to locate in areas with clean air," Liz Ulrich, supervisor of the DEQ's air quality analysis and planning section, said in a statement Monday. "Attaining air quality standards means cleaner air, better health and greater economic opportunities in this community. Removing the nonattainment status will make it easier for new businesses to choose Whitefish."

The EPA labeled much of Whitefish and some spots just outside the city limits as a "nonattainment" area in 1993 after an air monitoring instrument was installed at Markus Foods on Baker Avenue. That instrument, and later studies across the city, found levels of coarse particulate matter, or PM10, routinely exceeded a Clean Air Act threshold of 150 micrograms per cubic meter.

According to a 1993 analysis, the vast majority of that pollution — 86% — originated from city streets, both paved and unpaved. Another 6% came from paved and unpaved lots and alleys, while 7% came from residential wood-burning stoves. Trains, tailpipe emissions and the now-defunct Idaho Timber plant each accounted for 1% or less of Whitefish's PM10 problem, the analysis found.

The EPA warns that PM10 — particles less than 10 micrometers in diameter — are hazardous because they can get deep into people's lungs and even their bloodstreams, causing heart attacks, irregular heartbeats, aggravated asthma and other respiratory issues, and premature death in people with heart or lung disease.

After being classified as a "nonattainment" area, the city of Whitefish and Flathead County got to work on a plan to reduce dust that required paving, prioritized street-sweeping and specified the types of material that may be used for sanding and chip-sealing.

The DEQ said that effort paid off, and the EPA recognized the city's PM10 levels were in compliance from 1997 through 1999.

"Whitefish has continued to demonstrate attainment based on quality-assured monitoring data collected from PM10 monitoring in the area from 2015 through 2019," the DEQ said in its recent application to the EPA. Wildfire smoke events outside the city's control were omitted from the data used in that determination, per federal reporting protocols.

The DEQ previously has not asked the EPA to redesignate Whitefish as an attainment area under the Clean Air Act, though state officials have made such requests a priority in recent years, sending 10 to the EPA since 2016. The DEQ says the nonattainment label can result in more stringent requirements on businesses, hindering economic development.

"It does entail quite a bit of work and technical analysis," Ulrich said in an email. "In the past five years, we have made these a priority, especially since 2019. We recognize that it is important for the communities and the economic development of the areas to remove the nonattainment area designation."

The state's application was sent to EPA acting Regional Administrator Deb Thomas on Aug. 6. Ulrich said the agency has six months to determine whether the application is complete, and then a year to decide whether Whitefish is in compliance.

If the application is successful, Whitefish will enact a maintenance plan to keep its air healthy into the future.

Assistant editor Chad Sokol may be reached at 406-758-4439 or csokol@dailyinterlake.com.