Another day, same air pollution.
Pollution that has building up for more than a week has six counties of northern Utah under a health alert.
<div class=”p402_hide”>The Utah Division of Air Quality issued the alert for Box Elder, Cache, Davis, Salt Lake, Tooele, Utah and Weber counties.</div>
The National Weather Service says stagnant conditions will run until Thursday.
Officials issue alerts when atmospheric inversions trap cold air and pollutants in bowl-shaped mountain valleys.
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.