Air quality reaches unhealthy levels due to inversion

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SALT LAKE CITY — If the Wasatch Front's nasty temperature inversion and resulting smog is making you cough, clear your throat or leading to teary eyes, don't curse the reaction, praise it.

A state toxicologist says it is just your body fighting back with phlegm and tears to protect your respiratory system.

The federal threshold that classifies "unhealthy" air for sensitive groups is set at 35 micrograms per cubic meter of PM2.5, or fine particulate matter invisible to the naked eye but potentially injurious to your lungs.

On Tuesday, PM2.5 levels climbed to 70 micrograms per cubic meter, and by midafternoon Wednesday, levels were beginning to eclipse 48 in the Salt Lake Valley.

Compared to last winter, when Salt Lake City experienced its warmest winter on record and snow was practically a fantasy, there was a marked absence of prolonged temperature inversions; this February's fog and pollution is much worse.

Toxicologist Steve Packham, who works for the Utah Department of Environmental Quality, said it's bad, but most people's biological defenses are equipped to deal with the increased levels of pollution.

"Those who are sensitive to symptoms of air pollution might be more likely to experience them due to these inversion events, such as having asthma episodes triggered or the increased production of mucus or phlegm. If these symptoms go away when you go inside, there's nothing to be afraid of. Those symptoms are basically your body responding to foreign elements."

Packham compared the bad air to smoking cigarettes.

"There are 20 days like this or 20 days of pollution packed into that one cigarette," he said. "Some people smoke several cigarettes a day and they are physically able to deal with that stuff. It doesn't mean that it is good for you. It can take years off your life, but you don't drop dead."

He said people are exposed to varying levels of air pollution all the time and biological responses help us cope.

"The most important thing to remember is that every individual has their own level of sensitivity, and people need to be sensitive to that," Packham said.

University of Utah scientists are gathering data both on the ground and in the air to evaluate pollution levels and trouble spots. Thursday students and professors doing atmospheric research released a weather balloon to get a closer look at the particulates within the cloud of pollution.

"All of these things are really important to know," Erik Crosman, of the University of Utah, said.

If there are any redeeming factors associated with Utah's inversion episodes is that they are predictable and temporary. Packham pointed to a worldwide air quality index that maps pollution around the globe, and Southern California numbers on that scale in particular.

"In Utah we can predict them and we know they are not going to last forever," he said. "It is a lot healthier if you know you can deal with these things than if you were in Los Angeles and you had to deal with them every day."

The air quality index is a different yardstick than the EPA's particular threshold for PM2.5, and the numbers can look daunting.

Photo: Ravell Call/Deseret News
Photo: Ravell Call/Deseret News

On Wednesday's map, Salt Lake City sat in the unhealthy category at 133, Fresno sat at 107 and a Pahala, Hawaii, was inching up the meter at 132.

Some spots in Australia, South Korea, Turkey and even Ireland were downright nasty in the "red" zone, while some spots in China, India and Serbia were classified as "hazardous."

"The orange and reds hit more often in California than here. It is never green or good there. It is sad that they are living in that condition, but they are living. … If we can through these next few days, we should be OK."

Lead forecaster Linda Cheng with the National Weather Service in Salt Lake City said the high pressure system keeping the inversion in place along the Wasatch Front and in Cache Valley will remain through Friday.

A weak storm will brush by Saturday that could chip away at the gunk, followed by a stronger storm that may prove even more helpful at washing away the air pollution.

Cheng said forecasters are hopeful a more lively storm will hit late next week and scrub this inversion away for good.

Contributing: Jed Boal


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