According to a new report, counties in several Western states have unhealthy levels of ozone pollution, including Wyoming’s Sublette County.

While most of the country has much cleaner air than a decade ago, the American Lung Association's annual State of the Air report highlighted Wyoming's Upper Green River Basin as an example of the growing problem of smog in the rural mountain west. Ongoing drought, dust, and wildfires all contribute, as does air pollution from oil and gas development.

But Steve Dietrich from Wyoming’s Department of Environmental Quality says it is important to note that the study examined data from 2011 through 2013 and since then, the air has gotten cleaner.  

"I’m not saying it's not valid or not useful," Dietrich said. "What I would say is that it's a snapshot in time based on that data that’s available."

Since then the state has put in place new emissions controls on oil and gas development. And as Dietrich pointed out, in Sublette county, the just isn't as much drilling going on.