'We have great air quality at the moment': Utah’s inversion season is over

'We have great air quality at the moment': Utah’s inversion season is over

(Carter Williams, KSL.com, File)


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SALT LAKE CITY — Finally some good news.

Northern Utah’s 2019-2020 inversion season is over after the Utah Division of Air Quality stopped needing to issue action forecasts for poor air quality related to the meteorological phenomenon, state environmental officials said Wednesday. It put to a close a stretch where the region is most at risk for higher air particulate matter.

The winter’s inversion period wasn’t bad this time around due in part to consistent weather patterns and better action from individuals. The division reports there were no "red days," where the air is deemed unhealthy and there were just three total "orange days," where air quality is unhealthy for sensitive groups. One of those days happened in Salt Lake City last December and the other two were reported in the Cache Valley in January.

"The last two years we’re really had good air quality during the winter," said Jared Mendenhall, spokesman for the Utah Department of Environmental Quality, which oversees the air quality division.

"We've had people that are working really hard and are taking air quality seriously, but we've also had some really good weather patterns that have really just kept kicking out the pollution before those inversions set up (for long periods of time)."

Inversions are created when warm air locks cooler air below it, almost like a lid. It’s a problem because that means pollution is trapped underneath inversion and stays in the atmosphere. When particulate matter is below 35.5 micrograms per cubic meter, it falls under the federal guideline for acceptable air quality. Good air quality is defined as anything below 12 micrograms per cubic meter, according to the air quality division.

Weather patterns heavily factor into this. If a series of high-pressure systems move over the Wasatch Front, it could keep pollution trapped for days until a cold front comes through and moves the air along. The longer the inversion, the poorer air quality gets. University of Utah researchers have recorded some of the Wasatch Front’s inversions lasting as long as one to two weeks.

This table, created by the Utah Division of Air Quality, shows the possible different air quality levels.
This table, created by the Utah Division of Air Quality, shows the possible different air quality levels.

Luckily that hasn’t been the case during recent winters, Mendenhall pointed out. That’s partly why the Utah Division of Air Quality only reported three orange and no red days during this inversion season.

Pollutants are the other part of the air quality equation. Environmental officials have tried to reduce what gets put in the air and that’s been increasingly difficult because Utah’s population continues to grow. Tier 3 fuel arrived in Utah about the same time the inversion season began and that’s expected to cut down on emissions produced in the state. Mendenhall added that Utahns have also done a better job reducing emissions through commuting.

"We're starting to see cleaner cars and as more and more of those cleaner cars show up, it's going to improve air pollution," he said. "People are taking TRAX and using public transit, starting to use better strategies with their automobiles and approaching life with a better eye toward air quality — and that's great news. We've seen air quality improve consistently over the last 10 years. We’ve also seen the standards tightened."

This year’s inversion season ends amid the COVID-19 pandemic. That’s meant people have been asked to work from home and remain home as much as possible the past few weeks as a way to reduce the spread of the novel coronavirus. It has meant fewer vehicles on roads, but that likely hasn’t impacted Utah’s air quality much because there have been several storm systems that have swept through the Wasatch Front during the same time, Mendenhall said.

If the coronavirus has any impact on air quality, it may come in the future from changing habits.

"We have great air quality at the moment and the thing that we just encourage people to think about as they're working from home and as they're teleworking, that hopefully they can start to see that as an opportunity long-term," he said. "And when the wintertime comes in the next season and the inversion starts, they may have recognized and figured out a few things that make it possible so they can telework. And perhaps they’re also recognizing that they don’t need to use a car as much."

While the inversion season is over, the focus now shifts to Utah’s other period of poor air quality. The division will start issuing ozone forecasts in May, which will last through the end of summer.

Ozone has similar air quality standards, which means there are good air quality days through unhealthy and even hazardous days.

"It's an oxidant, so when you breathe it in, it's akin to giving your lungs a sunburn and it can irritate people who have asthma and other pulmonary or cardiovascular issues," Mendenhall said. "We are moving into the ozone season, so the same steps that you take to reduce emissions in the winter can be used in the summer."

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Carter Williams is a reporter who covers general news, local government, outdoors, history and sports for KSL.com.

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