When the U.S. Environmental Protection Agency (EPA) proposed strict new smog standards earlier this month, it released a map highlighting the counties around the country likely to be affected. Montana was the only state in the lower 48 completely free of colored blobs representing potential violations, and state air quality experts say that big swath of clean air is a big deal.
"Ozone," says Bob Jeffrey, air quality specialist with the Montana Department of Environmental Quality (DEQ), "is one of the toughest pollutants this country has. In large part it results from personal lifestyle choices that we make as Americans, mostly having to do with all the motor vehicles we drive around."
The EPA's proposal would set the standard for ozone within a range of 60 to 70 parts per billion (ppb), down from the current 75 ppb standard set in 2008. Montana's monitoring stations haven't detected ozone levels within that range. But a couple locations—including, interestingly, Glacier National Park—are close.
Billings, Jeffrey explains, has the highest ozone level in the state. Between 2005 and 2007 it averaged 59 ppb. Meanwhile, a monitoring station in West Glacier detected an average of 57 ppb between 2006 and 2008.
"What could be going on in West Glacier—and this is just pure speculation on my part—is that...we could be getting emissions generated in the Flathead Valley getting transported toward Glacier Park," Jeffrey says.
Some have used Glacier's ozone level as a reason to oppose the proposed standards, arguing that if pristine parks in the West can barely achieve them then cities have little chance. But Glacier's ozone level hardly stands out among all national parks. According to National Park Service data, a few national parks in California consistently record ozone levels above 100 ppb.
The only impact new standards would likely have in Montana, Jeffrey says, would be to add more monitoring stations, perhaps in Missoula.
"It's the second-biggest urban area in the state behind Billings," he says, "and maybe that stuff sits there and stews long enough that we're getting some ozone formation."