According to the Utah Department of Environmental Quality, Utah has a "Red Light, Green Light" program, which directs activities according to the air quality.
On red days, wood burning is prohibited and residents are asked to drive as little as possible. On yellow days, residents are asked to voluntarily restrict wood or coal burning, and are also asked to drive as little as possible. And on green days, wood burning is allowed.
"We have good air quality," said Bob Swensen, Summit County Environmental Health Director. "You can tell a difference. Drive down to the [Salt Lake Valley] and take a look, then come back here. It can get really bad there. December and January is when they get hit the hardest. And then they get a good breeze blowing through like the storm blowing in that cleans it all out, and then it starts all over again."
PM2.5 is a common pollutant that causes inversion. PM2.5 are fine particles in the air measuring 2.5 micrometers or less, which can be released from cars, power plants and forest fires.
According to the Environmental Agency, these particles can cause major heart and lung problems, including irregular heartbeat, nonfatal heart attacks, aggravated asthma, decreased lung function and respiratory issues, such as difficulty breathing or coughing.
Those with heart or lung disease, children and the elderly are the most susceptible to PM2.
The EPA also notes that PM2.5 can cause environmental damage by making streams and lakes acidic, depleting soil nutrients, damaging forests and crops, and affecting ecosystem diversity.
There are two monitors set up in Summit County to measure PM2.5 levels. One monitor is set up in Kimball Junction and the other in Coalville.
"The one in Kimball Junction is a little higher than the one in Coalville, but they are both well below the action level," he said.
Action levels are designated yellow and red days, when the public is asked to take pollution-reducing actions to reduce the level of PM2.5.
Swensen pointed out that sometimes, when it gets cold in Summit County, frozen water in the air can make it look hazy, but it isn't from pollution.
"It's almost like a cloud that hasn't formed into a cloud," he said.
Summit County does see a slight increase in PM2.5 levels when Salt Lake County experiences inversion.
"Every time we see an inversion in the valley, like we had recently, we do get a rise in the PM2.5 levels, and I think a little has to do with the spill over from the summit," he said. "They are in the red zone down there. We might start bordering on the yellow, but we're not quite there. One-hour readings will be up there but the 24-hour average is going to be well below that."
PM2.5 levels of 20 parts per million put air quality in the yellow zone, and 35 parts per million puts air quality in the yellow zone.
According to Utah Moms for Clean Air, Utah clean air advocates, Salt Lake Valley PM2.5 levels reached close to 90 parts per million on Jan. 8.
"It will burn your eyes and you can taste it. It's horrible stuff," Swensen said. "In Summit County, we might have gotten up to 20 or 25 in a one-hour reading, but our average is between 10 and 15."
In the four years that the county has been measuring PM2.5 levels, Swensen said they haven't seen any substantial increases.
"We haven't seen any trend we can pinpoint. It's been staying about the same." he said. "The air quality is green. So by all indications, we're in good shape up here. We just have to keep it that way," he said.