Salt Lake County's air quality slipped briefly into the "red" zone on Thursday, meaning that wood and coal stoves or fireplaces could not legally be used. But when a weak storm system approached, it blew the gunk out and air quality improved.
The Utah Division of Air Quality issued a health advisory Thursday morning, saying particulate pollution was so high that people sensitive to the pollution should avoid prolonged or heavy exertion outdoors. They are "those with respiratory or heart disease, the elderly and children," says the release.
But by 3:30 p.m. air quality in Salt Lake County was listed as "yellow," with officials calling for voluntary restrictions. People were asked not to burn wood or coal, and to reduce vehicle use by consolidating trips.
"Industry should optimize operation conditions" to reduce pollution, it adds. Sensitive people still should avoid prolonged or heavy exertion outdoors.
Cache, Davis and Weber counties were listed as having "yellow" conditions also. Utah County's air quality was in the "green" category, meaning it was clear.
The National Weather Service predicted patchy fog and snow Friday in Utah's capital, followed by breezy weather Saturday. That seemed likely to brush out even more of the pollution.