A consequence of our geography, industry, and population density, inversions result when warm air traps polluted cold air in mountain valleys. Winter temperature inversions result in high particulate matter concentrations and the nasty haze we see, taste, and smell when we're outdoors. One can imagine, without too much difficulty, that air you can taste and smell probably isn't good to breathe either.

There's incontrovertible evidence linking poor air quality to adverse health outcomes. This is especially true for people with pre-existing conditions such as heart disease, stroke, asthma, and chronic obstructive pulmonary disease. However, healthy people are at risk too.

RELATED: Air Quality and Outdoor Exercise or Work

The air quality index from the Environmental Protection Agency is a measurement of major air pollutants, including particle pollution, ground level ozone, sulfur dioxide and nitrogen dioxide, and carbon monoxide. The index provides guidance as to the safety of the air quality. In Utah, the index is reported daily on both the radio and television. You can also download the airnow.gov app for your smart phone, and receive the air quality index for an entered zip code.

Here are some tips to help you maintain an active lifestyle when our air quality is poor. And note: It is important to remember that a scarf or mask doesn't protect you from the poor air quality.

• Exercise earlier in the day. Both inversions and ground level ozone tend to accumulate throughout the day
• If possible, exercise "above the inversion" at a higher altitude — that way you'll get some altitude training too.
• Consider indoor exercise, if the first two options aren't practical

Of course we want people to be physically active, and better yet, to be active outdoors. However, it's important to keep in mind that an adult exercising at a moderate level of exertion exchanges about six liters of air per minute. An athlete running at 70 percent of their maximal oxygen uptake for the length of a marathon inhales the same volume of air as a sedentary person does in two days. Going back to an earlier comment on air you can taste and smell, that's not the time you want to go out for a 30 to 60 minute jog.

Finally, think about what you can do as an individual to reduce your contribution to Utah's poor air quality by using public transportation when possible, combining driving trips, eliminating the time your car idles, avoiding wood-burning, and replacing or installing ultra-low nitrogen oxide water heaters. If we all do our part to clean the air, it will make the environment safer for the outdoor exercise we love.