KALISPELL, Mont. -- Some may think wildfire smoke is the only threat to air quality, but our mackenzie it can get bad in the winter too.
An inversion blanketed the whole Flathead Valley area on Saturday and it's the reason why air quality can be bad in the winter.
Flathead County’s Environmental Health Department said inversions decrease ventilation, which keeps any pollution created in the valley from moving out of it.
On Saturday night, air quality for most of Montana was at good, but some places were in moderate earlier in the day.
Flathead Health workers said wood-burning stoves are not a pollutant problem in the Flathead, but can cause problems in Missoula.
There are other pollutants that can cause bad air quality too.
"Vehicle traffic is another one that can cause particles to build up this time of year with the traffic and we have a sealing so again none of the pollution is leaving," said Flathead County Sanitarian Wendee Jacobs.
Jacobs said it's also one of the reasons why open burning is not allowed from December to February.
"This is a typical weather pattern and we would see exceedances and that's why the limit outdoor open burning during these periods," Jacobs told NBC Montana.
Even after the month of February, open burning goes on a day-to-day basis because Jacobs said inversions can still happen in the months after.