Utah Asthma Program
Utah Asthma Program

Winter Pollution

During the winter, particulate matter (or PM) is the main pollutant of concern. PM is made up of soot, dust, and vehicle emissions. It is measured in two sizes, 2.5 and 10.

  • PM10 can usually be filtered by nose hair and lung cilia and coughed out.
  • PM2.5 is a bigger concern because it is small enough to get past the body's natural defense systems. When breathed in, PM2.5 can get deep into the lungs where it becomes trapped, aggravating current health problems like asthma.

Winter Inversions in Utah

PM levels increase during Utah's Inversions. Inversions form when the right weather conditions—cold temperatures and no breezes—cause the cold air and pollution to become trapped in the valley.

An inversion will stay until wind or a storm front comes through. The longer the inversion lasts, the more pollution there is in the air.


Symptom Tracking Sheet - A sheet to assist in tracking PM2.5 levels and your symptoms to plan physical activity.