After years of clear, clean skies, Flathead County took a major step back last year in air quality, according to a new report by the American Lung Association.

Flathead County earned a “C” grade for several unhealthy short-term particle pollution days last year

That grade is down from an “A” every year since 2004.

The county had four “orange days” in 2014, which are described as unhealthy for sensitive groups. Children, the elderly, diabetics and those with asthma are considered sensitive groups.

Flathead County has more than 8,000 people living with asthma and more than 15,000 residents 65 years or older.

As a state, Montana does very well in terms of levels of ozone but struggles in many cities with levels of particle pollution. This pollution is caused by “microscopic specks of soot, metals, acids, dirt, pollen, molds and aerosols that are tiny enough to inhale.”

These particles can penetrate into the lungs and work their way into the bloodstream and can potentially cause health problems like asthma and heart attacks as well as cancers.

Many of Montana’s low scores have come from recent dry seasons and strong forest fires. Missoula, Lewis and Clark, Ravalli and Silver Bow counties, which were in the path of forest fire smoke plumes last year, all scored “F” grades on the American Lung Association’s report.

Missoula County had 14 orange particle days and seven red particle days — days unhealthy for everybody. It is ranked the 11th-most particle-polluted region in the nation. Ravalli County is tied for the ninth-most-polluted county in the country, thanks in large part to recent dry summers and smoke from forest fires.

A full 93 percent of unhealthy days in Ravalli were attributed directly to forest fires. That number drops to 86 percent in Missoula, 75 percent in Lewis and Clark and 56 percent in Silver Bow.

Of the fully monitored counties, only Powder River and Richland counties scored “A” grades.

Ronni Flannery, the Montana Healthy Air Director with the American Lung Association, said despite poor grades, Montana’s air has still made major strides.

“We know that the Clean Air Act and state and local regulatory controls and strategies work because we’ve seen Montana’s air quality improve over the past 16 years and send the health benefits that have come with cleaning up the air,” she said.

Nationally, around four in 10 Americans live in a county where ozone or particle pollution levels are unhealthy. That’s more than 138 million people.

From 2008 to 2012, Flathead County had no measurable unhealthy particle pollution days, according to statistics on the American Lung Association’s site.

All unhealthy sites in Montana are experiencing short-term particle pollution, which can spike for hours or weeks. Year-round particle pollution hovers around unhealthy levels the entire year.

Going forward, the American Lung Association and Montana Department of Environmental Quality seek to combat diminished air quality they claim as a result of climate change by strengthening ozone standards, protecting the Clean Air Act and leaning on Congress to fund the Environmental Protection Agency.

To see the statistics for Flathead County or any other measured county, visit www.StateOfTheAir.org.