Most Utahns are familiar with the “inversions” that occur each winter. Here in Utah, we associate an inversion period with poor air quality, but inversions are a natural atmospheric phenomenon that occurs world-wide. Inversions occur in regions with similar topography to ours such as the Los Angeles Basin and Denver. An inversion happens when a cold air is trapped in a valley during times of still air and cold temperatures. Humidity rises, and fog forms. Cold air isn’t the only thing trapped by inversions, though—our emissions also stick around until the weather shifts. Our largest air pollutant in the winter is particulate matter (PM). PM is a pollutant that comes from our tailpipes, wood-burning, and dust and also forms through chemical reactions of other pollutants in cold temperatures. PM 2.5 (particulate matter that is less than 2.5 microns in size) is dangerous to human health because its small size means it can enter our lungs and bloodstreams more easily.

In the summer we don’t see the haze and fog of the winter, so it is easy to forget to check the air quality. Unfortunately, there’s an invisible summertime threat: ground-level ozone. While ozone is beneficial in the upper atmosphere where it provides a barrier that captures harmful ultraviolet radiation from the sun, ground-level ozone is linked to various respiratory illnesses in humans. Ozone is a secondary pollutant which means that a chemical reaction must take place in order for the pollutant to be created. Ozone is created when our emissions react together in the hot summer sunlight. Since Ozone concentrations are highest during the heat of the day, exercising in the morning or late in the evening can reduce your exposure.

current conditions and standards How has our air quality changed Annual ozone trends