Several areas in the Pacific Northwest are experiencing unhealthy air.
Winter weather conditions have trapped air pollution near the ground.
Much of the pollution contains fine particles from burning wood. Those fine particles can cause lung and heart damage. The conditions have led to temporary bans on woodburning stoves and outdoor fires.
Michael Toole with Idaho’s Department of Environmental Quality said people can protect themselves from the pollution by staying indoors.
"We do recommend that anyone included in the sensitive group whether they be children, elderly or those with already compromised respiratory systems or cardiac issues to limit their exposure outside especially during the morning or evening hours when pollution levels can be higher,” he said.
Air pollution levels have reached unhealthy levels in Idaho’s Pocatello and Treasure Valley regions, Washington state’s Stevens, Pierce and Snohomish counties, and in Oregon’s Oakridge, Klamath Falls and Lakeview areas.
In some instances, the resulting air pollution could lead to tighter regulations on burning next year.
The Klamath Falls Herald and News reported that could be the case for Klamath County. The county was out of compliance with federal standards on Wednesday for a second time, and projections for Saturday would bring make for a third time.
That would mean the region hasn't met its goals, leading to tighter 2014 restrictions, including a ban on open fireplaces and further regulation of industry.
A county commissioner says he'll seek an exception on the grounds the recent conditions are an extreme weather event.
(The Associated Press contributed to this report.)