First, it was carbon monoxide; now it's PM 2.5, or particulate matter.
"To give you an example of how small that is, the human hair is approximately 60 microns in diameter, so 2.5 is very small," explained Glenn Miller, the borough's transportation director.
He says his department has spent the past couple of years trying to determine what's causing PM 2.5.
"We have been focused on wood smoke because the initial data that we have indicates that wood smoke is a significant contributor," Miller said.
When energy prices spiked a couple of years ago, that prompted more residents in the Fairbanks area to switch to sources that are considered big contributors of air pollution.
"Wood and coal sources all of a sudden become very attractive because they're much cheaper than the alternative, especially when fuel oil gets up to $4 and $5 a gallon," Miller said.
In Fairbanks, the drop in air quality happens during a temperature inversion -- when a layer of warm air sits on top of cold air, trapping pollution close to the surface.
"It's a case where the meteorology is very much against us. If we happen to have more air flow, for example, like Anchorage does, then we wouldn't have this problem, but because we have that very, very tight, cold inversion, we're going to be heating more and the pollution gets stuck," said Catherine Cahill, an associate professor of chemistry at the University of Alaska Fairbanks.
Cahill has studied PM 2.5 since the late 1980s.
She says it is a serious health hazard.
"It increases asthma, you can have premature death where people who are already respiratorialy compromised from illness, or the very young or the very old can get a little bit sicker and potentially die sooner, so there are some serious health effects associated with the particulate matter concentrations above the standard," Cahill said.
When the Environmental Protection Agency tightened the fine particulate standard in 2006, changing the standard from 65 micrograms per cubic meter to 35, Fairbanks began exceeding the standard on a regular basis.
"Our concentrations have gone up this year and that means, even with the old standard, we'd be violating. With the new standard, it means we're toast," Cahill said.
"The concentrations are too high, we are going to be out of compliance, and now we have to come up with, how do we come in to compliance," she continued.
The Borough Assembly introduced a draft ordinance in July regarding wood smoke regulations.
The ordinance would have forced residents to upgrade to EPA certified stoves and create temporary bans on wood burning.
That caused controversy, and after public outcry, the Assembly stepped back.
Borough officials plan to encourage residents to voluntarily make changes to help cut back on PM 2.5.
Even though initial data shows wood smoke is a big contributor, the borough says other studies also need to be done to find out how much particulate matter comes from fuel oil, waste oil, coal and vehicles.
"Before we can impose any programs or restrictions, we really need to understand where the sources are coming from," Miller, the transportation director, said.
"It's going to be a big project to tackle because you can't single out one source," Thompson said.
The Assembly voted unanimously in mid-January to approve an agreement with the state, putting the borough in charge of air quality.
Borough Mayor Luke Hopkins says he will introduce an air quality plan in the coming months.
The borough has less than three years to submit an implementation plan to the EPA, or risks losing federal funding.
The borough's transportation department is conducting a study now that is measuring the amount of PM 2.5 that's emitted from vehicle exhaust.
The initial data gathering should wrap up by this weekend.
Contact Lori Tipton at firstname.lastname@example.org