Utah health officials last week urged principals to keep school children indoors during recess and advised other to avoid prolonged exertion because of worsening air quality.

 

An inversion of cold air trapped dust against the Salt Lake valley floor and sent the region’s Air Quality Index from moderate to unhealthy. Portions of the state were ranked as having the most polluted air in the country for the third day in a row last Tuesday, according to the Air Quality Index, which is published by the Environmental Protection Agency.

 

From Jan. 9-12, data showed that Salt Lake City exceeded standards for tiny specks of pollution known at PM2.5 (particulate matter). By Tuesday, PM2.5 exceeded federal standards nearly three- fold.   By mid-afternoon Friday, a weather system had blown out the inversion and air quality had improved to a rating of moderate. The forecast at the EPA’s www.airnow.gov website, however, called for unhealthy conditions to resume.