SALT LAKE CITY — The dreaded ugly, unhealthy inversions: There have been 10 sickening days of them so far this winter, and the season isn't even half over.
An average of 41 times each winter season, dreary gray haze, smoke and pollution dominate the skies of Utah's capital during inversions, according to utahweather.org. On about a fourth of those days — usually during consecutive days of inversions — pollution builds up and creates red air action days.
Utah, Davis and Weber counties usually have similar episodes of gray skies and gunky air.
Blame the bad air on the Salt Lake City's majestic mountains, so many people living here and, yes, the weather.
"We're at the mercy of meteorology," said Bryce Bird, branch manager for the Utah Division of Air Quality. When high pressure dominates and there aren't regular storms, inversions occur, and they eventually result in poor air quality.
Inversions and bad air quality usually go hand-in-hand.
Salt Lake City is surrounded by mountains. Certain meteorological conditions, like cold temperatures without wind, can cause the cold air to become trapped. Pollution has nowhere to go and begins to build up. Warm air gathers above and holds the frigid air and pollution in place, like a lid.
The condition is called an inversion because it is the reverse of a typical weather pattern. A storm or wind is required to scour out the dirty, cold air.
Thursday and for at least the next two days, until Sunday, Salt Lake's air quality is predicted to be moderate, with a yellow rating. However, that reprieve from the red might be short-lived. Pollution could build up on Sunday, Monday and Tuesday, according to KSL meteorologist Dan Pope.
The four-month inversion/air quality monitoring season begins on Nov. 1 and continues until March 1 in Utah's most populous counties.
Salt Lake City has already experienced 10 red no-burn days so far this year, one more than the annual average during the past nine years.
Salt Lake's recent worst pollution winter was 2006-07, with 30 red days. The winter of 1981-82 also saw many long inversions.
The clearest winters were those of 2004-05 and 2002-03, with only two red days each.
Wood-burning restrictions went into effect in 2001-02 as a proactive measure to improve air quality.
Despite today's challenges, Utah's air is significantly cleaner than it was 25 years ago. Better pollution control is a major factor.
But, "It's still an issue," Bird said. "It's still impacting people's health."
He said less driving during winter inversions is the best solution. Or at least having residents drive their newest vehicle, the one with the best pollution controls.
Also, he recommends that people don't idle their cars in the driveway or at drive-ups.
"Idling is zero miles a gallon," Bird said.
The Utah Division of Air Quality has 50 tips for curbing pollution on the Web at www.cleanair.utah.gov.
(Red, yellow or green days identify burning conditions. A red day means woodburning is prohibited and those with respiratory problems should limit their outdoor activity. A yellow day means a voluntary no-burn day and a green day means burning is allowed.)
e-mail: lynn@desnews.com