In this Jan. 5, 2013 photo, an inversion cloud partially obscures shrouds the cities in the northern Wasatch Front from the Snowbasin ski resort boundary in Utah. A group of Utah doctor

 

              In this Jan. 5, 2013 photo, an inversion cloud partially obscures shrouds the cities in the northern Wasatch Front from the Snowbasin ski resort boundary in Utah. A group of Utah doctor
In this Jan. 5, 2013 photo, an inversion cloud partially obscures shrouds the cities in the northern Wasatch Front from the Snowbasin ski resort boundary in Utah. A group of Utah doctors is declaring a health emergency over the Salt Lake City area's lingering air pollution problem. Utah Physicians for a Healthy Environment planned to deliver a petition Wednesday, Jan. 23, 2013, demanding immediate action by elected officials. (AP Photo/Standard-Examiner, Robert Johnson)