Residents in the Rattlesnake valley woke up to Unhealthy to Very Unhealthy Air Quality on Thursday morning after some burning debris piles spread to nearby forest undergrowth producing heavy smoke.

Missoula County Health Department Air Quality Specialist Sarah Coefield said there was a controlled burn in the Rattlesnake on Wednesday, but that’s not where Thursday morning’s heavy smoke originated.

“It appears some piles they had burned last week woke up from the nice sunny day we had on Wednesday and those piles came back to life and the fire crept away from them,” said Coefield. “That fire burned overnight and produced smoke that got stuck in the inversion and just kept building up until we got smoke levels in the upper Rattlesnake that were Unhealthy last evening and returned back up to Very Unhealthy by Thursday mid-morning.”

Coefield said fire crews are working to put out the fires, but the smoke will linger unto the next weather system comes through.

“There is a cold front coming through,” she said. “It got stalled but it is still supposed to get here soon and bring with it some strong winds. Not a ton of moisture to start but there should be some strong winds to help scour that smoke away and get it out of people’s breathing space.”

Coefield expects conditions to improve throughout the day.