How Dangerous is Our Air?


Facts and Tips for Utah Athletes

An unborn baby’s lungs are full of amniotic fluid. Before we exit the womb, we’re incapable of breathing so mom delivers the requisite oxygen through the placenta, but once on the outside…we’re on our own. Our first breath fills our clean lungs with oxygen and—if you live in the Salt Lake Valley—microscopic particles of soot, exhaust, dust, aerosols, and other pollutants that cause inflammation, the precursor to disease.

Breathing this polluted air is highly correlated with an overall increased risk of death, and researchers in Canada found that people chronically exposed to pollutants are 20% more likely to die from lung cancer than those who breathe clean air—the same odds you face if you live with a smoker. Thankfully, your lungs have the capacity to filter an occasional dose of toxicity. But for Salt Lake Valley athletes, when is the air too polluted to exercise in?

We live and play in atmospheric layer closest to Earth, called the troposphere. The two biggest concerns for our health are ground-level ozone and particulate matter. Human activities, from vehicle exhaust to industrial emissions, contribute to both.

Ground-level ozone occurs when warming temperatures and sunlight react with engine and fuel gases in the air. Ozone levels increase in cities when the air is still, the sun is bright, and the temperature is warm. Ozone is therefore worse in the summer because of the ripe conditions. So don’t be fooled into thinking bad air is only a winter danger!

Particulate matter is a term used to describe the microscopic particles floating in the air. These particles normally can’t be seen with the human eye, but when there are a large number present we clearly see a dark blanket of smog—also known as a temperature inversion.

Salt Lake City’s unique geographic layout lends itself to temperature inversions. The surrounding mountains create a bowl where the warmer air acts as a lid and traps the colder air—and its pollution—in the valley. At times this causes Salt Lake City’s pollution levels to exceed cities five times its population! On average, only 5% of our annual days exceed the EPA standard of 35 micrograms per cubic meter, but in 2012 the Wasatch Front saw 22 days when the air quality was considered dangerous to human health. A scary statistic for athletes who run, cycle, and spend time outdoors year-round.

Observational and controlled human studies suggest air pollution adversely affects athletic performance because athletes take in 10–20% more oxygen than sedentary folks—exposing them to greater levels of pollutants. The size of these microscopic particles allows them to bypass some of our defense mechanisms, like our noses, allowing them to penetrate deep into the lungs where they create inflammation and oxidative stress (a harmful by-product of your cells producing energy). During exercise these particles can travel directly into the bloodstream, resulting in bronchoconstriction and reduced ventilatory flow, both of which negatively affect athletic performance. They can also contribute to conditions like asthma and chronic obstructive pulmonary disease.

Thankfully, Salt Lake athletes can travel up-canyon above the inversion to leave the toxic environment behind, but if you must stay in the Valley, you’re faced with the difficult question of when to exercise and when to stay in. While there is no hard and fast rule for when to avoid exercising in bad air, check out the sidebar for tips to help you decide when to choose the dreadmill instead of venturing outdoors.

Exercising Tips for Outsmarting the Smog

Check the Quality: It’s easy to find daily air quality for Salt Lake City at or You can also download the American Lung Association’s app for on-the-go readings. If it’s a red air day, skip the outdoor workout—spending the afternoon coughing or with a sore throat is not worth the runner’s high.

Hit the Trails: Cars and trucks emit toxic particles, so getting off the road and onto the trails is a smart decision. The farther you are from the source of the pollution the better the air quality, so hit the singletrack or canyons. Cyclists should choose lightly traveled roads or parks, and head out in off-peak traffic hours.

Get an Early Start: High ozone pollution levels require sunlight and heat, so get out early in the day before the ozone rises to harmful levels.

Sportsta dust mask

Wear a Mask: If you must ride city roads on high-pollution days, consider wearing a mask. We like the Sportsta™ from Respro® because it’s proven to filter out exhaust emissions and sub-micron particulates while allowing you to breathe easily during intense runs or bike rides. Get one online at


About Author

Matt Hart owns and operates Coaching Endurance LLC, through which he’s helped hundreds of athletes reach a wide range of fitness and endurance goals. Initially USA Cycling Certified as a coach, Matt now works mostly with runners and multisport athletes. Matt resides in Utah and practices what he preaches as a professional ultrarunner for Mountain Hardwear and Montrail. For more information on Matt, follow him on Twitter @TheMattHart. To read more of Matt’s work pick up Trail Runner Magazine, where he writes the “Ask the Coach” column each issue.

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