Inversion returns to Utah. Here's how long it's expected to last

An inversion begins to fill the Salt Lake Valley on Nov. 29, 2021. Inversion conditions return again this week.

An inversion begins to fill the Salt Lake Valley on Nov. 29, 2021. Inversion conditions return again this week. (Scott G Winterton, Deseret News)

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SALT LAKE CITY — After weeks of storms provided a breath of fresh air, it's back to inversion season for many Utahns this week.

The inversion is already in place. KSL meteorologist Grant Weyman explained that patterns have shifted and a high-pressure system has returned over the state after weeks of beneficial storms, which is causing the inversion. It also is helping push a storm currently in the Pacific Northwest up into Canada, Weyman added.

"Haze will kind of build up (throughout the week)," he said. "If you've been here long enough, this time of the year, when we're under a high-pressure system and things are pretty quiet for a while, the air quality tends to get a little worse."

Bryce Bird, director of the Utah Division of Air Quality, said the current inversion is expected to linger for most of the week if not longer.

Monday's conditions weren't as bad. Air Quality Index levels surpassed 50 throughout the Wasatch Front during the day, into what's considered "moderate" air quality. But air quality is expected to worsen as the system remains in place, meaning that levels above 100 — unhealthy levels especially for people with sensitive conditions — are likely by Thursday, according to Weyman.

A weak storm system is forecast to arrive Friday but it's unclear at the moment if that will move out the dirty air building up this week. Bird said it will depend on if that storm reaches the Wasatch Front and northern Utah regions and has enough energy to push out the stagnant air.

"For right now, we're anticipating for the conditions to persist long enough that concentration of air pollutions will increase up to levels that impact public health," he said.

With the forecast the way it is, Tuesday and Wednesday are already designated as mandatory action days. That means all state employees who can work from home will work remotely to reduce emissions into the atmosphere. Bird said people can reduce the amount of pollution during the inversion by driving less whenever they can this week, too

People aren't allowed to burn solid fuel sources at home, like a wood stove, unless the devices have been properly registered as the sole source of heat for their homes. Bird added that residents who don't have those sources can also help by turning their heat down a few degrees this week.

Some Utah counties have reinstated mask orders with the recent uptick in COVID-19 cases. But air quality experts say some of those masks — especially N95-quality masks — may also prove to be beneficial this week because of the inversion, too.

"They are effective at reducing particle concentrations that you're exposed to," Bird said. "These small ultrafine particles are the ones that can evade your body's natural defenses and really get into the deepest parts of the lungs. It would take an N95 mask to reduce that particle loading as we get those high levels (during an inversion)."

Other masks, such as homemade cloth ones, aren't beneficial during inversion or wildfire smoke events.

Utahns can check Air Quality Index levels for many places in the state through the KSL Air Quality Network.

Full seven-day forecasts for areas across Utah can be found at the KSL Weather Center.

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Carter Williams is an award-winning reporter who covers general news, outdoors, history and sports for


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