SALT LAKE CITY (AP) - Regulators are issuing an air pollution alert for seven counties along the Wasatch Front, home to 2 million Utah residents.
A pollution-trapping inversion or icy fog has given northern Utah the nation's worst air.
State monitors show Utah County has the worst air. It was exceeding federal standards by three times early Monday.
The Utah Division of Air Quality issued the alert for Box Elder, Cache, Davis, Salt Lake, Tooele, Utah and Weber counties.
For those who could, getting out of the mucky air was a priority Monday. Megan Peterson and her girls were just on the edge of the bad air, sledding at Mountain Dell Golf Course.
"We actually have been down in Arizona for six years. It's our first year back, and I forgot what the inversion is like," Peterson said.
Authorities are prohibiting wood burning and urging people to limit driving.
Doctors say people — especially pregnant women and children — should stay indoors, or at least avoid active outdoor exercise.
Valley temperatures across northern Utah weren't expected to break 21 degrees Monday.
Mountain temperatures are warmer, with Park City expected to reach 43 degrees.
According to KSL's weather team, a front is expected to move in Thursday that may provide some improvement to the air. A bigger storm is forecast for Jan. 28.
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