Stagnant air is blanketing the Wasatch Front, with a Class A health advisory in effect for Utah County.

"Due to the air stagnation, the Utah Department of Health suggests that the non-essential use of motor vehicles be reduced," Art King, environmental health scientist at the state's monitoring center, 261 W. 500 South, said Friday. That applies throughout the Wasatch Front.For Utah County, PM10 particulates, the smallest and most hazardous particles, violated federal health standards for the past few days.

The federal standard requires no more than 150 micrograms per cubic meter of the pollutant on a 24-hour average, but on Thursday the level was an unhealthy 197 at the monitoring station in Lindon, Utah County. Nearly the same level was noted on Friday morning at Lindon.

"Persons with heart or respiratory ailments should reduce physical exertion and outdoor activity," King said.

Since Jan. 1, the federal particulate standard has been exceeded more than two dozen times along the Wasatch Front, he added.