If you are from Salt Lake City or have visited Salt Lake City in the winter time, chances are you have experienced an inversion. What is an inversion and how does one happen?  During an inversion normal conditions (cool air above and warm air below) are switched or inverted and a layer of warm air traps a layer of cold air in the valley.  

The warm air acts like a lid trapping pollutants near the valley floor.  The longer the inversion lasts, the more pollutants become trapped.  An inversion will stay until wind or a storm front comes through.  Inversions typically last a few days to a week but can last longer.

Studies have found that the length of the inversion rather than the inversion itself, is a factor. This means the longer the inversion lasts, the higher the likelihood of asthma complications.
Unfortunately for asthma sufferers, an inversion can be more than just a minor annoyance. A person with asthma has an increased likelihood of getting upper respiratory infections which can lead to flare ups and worsening of asthma symptoms.

It can also reduce lung function by causing the lining of the lungs to be inflamed. As a result asthma sufferers may experience an increase in asthma symptoms and asthma attacks which can result in missed days of work and school.

In addition, there is an increase in asthma related emergency room visits. Talk to your doctor about taking steps to control asthma, and consider stepping up use of controller medications if your asthma is not being well controlled.