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Tom Smart, Chopper 5, Deseret News
An inversion of smog hangs over the Salt Lake Valley Thursday.

SALT LAKE CITY — The weather is not the only frightful thing outside these days. The air Utahns are breathing is pretty awful as well. Cold temperatures and excessive smog have veiled the Salt Lake Valley and much of northern Utah under a thick blanket of muck and mire — otherwise known as a dreaded inversion. Ugh!

Inversions occur during winter months — typically between Thanksgiving and Valentine's Day — when normal conditions such as cool air above and warm air below are inverted. Inversions trap a dense layer of cold air under a layer of warm air acting much like a lid that traps pollutants within the cold air near the valley floor.

Along the Wasatch Front, valleys and their surrounding mountains act as a pot, holding the air down. The longer the inversion lasts, the more pollutants become concentrated within the weather pattern.

So bad is the air these days that red alerts and health advisories have been issued in Cache, Davis, Salt Lake and Weber counties. In addition, Box Elder, Tooele and Utah counties are under yellow alert air quality action alerts.

"Every minute that goes by, (we have) all the vehicles, houses, industry and everybody … creating pollution," said Bo Call, air monitoring section manager with the Division of Air Quality. "That pollution just goes up and gets trapped."

To make matters worse, inversions can be extended for days when snow covers the valley floors and reflects the sunlight needed to break up the inversion. This pattern allows pollution to continue to concentrate near ground level and also increases when fog is present to facilitate chemical reactions that create even more pollution. Yuck!

Call said when the situation becomes critical — resulting in a red alert status — health advisories are issued.

According to the Utah Department of Environmental Quality, a health advisory indicates that the air quality is especially unhealthy for people with sensitive conditions such as respiratory or heart disease along with the elderly and children — who should limit prolonged or heavy exertion in the outdoors.

19 comments on this story

While the current inversion isn't the first since the recent cool-down began, it is the most potent thus far.

And according to KSL chief meteorologist Kevin Eubank, it will be around for a little while at least. Oy!

"We very well could be in this pattern for a week and a half, maybe more," he told the Deseret News. Relief could be on the way in 10 to 14 days, he added, when the next significant weather pattern moves into the area.

"For the immediate future, the air quality will remain in the moderate to unhealthy range," Eubank said.

"It's bad air, that's all there is to it," he said. "It's bad air."

e-mail: jlee@desnews.com