SALT LAKE CITY -- Utah has long been known as an outdoor lover's utopia. The skiing and mountain biking are among the best anywhere. And the snow-clotted mountains that tower around Salt Lake give this city a mythic quality during winter.
But lately, the Wasatch Front, the corridor of cities and towns where most Utahans live, has acquired a reputation for a less enviable attribute: bad air.
For the last few years, the area has been grappling with one of the nation's most vexing pollution problems, where atmospheric inversions during the winter months lead to a thick fog of dirty air cloaking the region.
"Obviously, this is not acceptable," said Bryce Bird, the director of Utah's Division of Air Quality. "The public is fed up with it. The concern for them is that it is not being addressed fast enough."
According to the division, Salt Lake County has experienced 22 days this winter in which pollution levels exceeded federal air quality standards, compared with just one last year.
The air pollution has gotten so bad at times that it has prompted warnings from local doctors, spawned protests at the State Capitol and led to a variety of legislative proposals in the hopes of confronting the problem before it gets worse.
It is not that the region necessarily emits more pollution than other large metropolitan areas, or that the problem is especially new, Mr. Bird said. What makes the situation here different is the confluence of topographic and meteorological factors.
When heavy winter storms sweep through the area, they leave snow on the Salt Lake Valley floor. But intermittent warm fronts trap the cold air, creating the effect of a lid on a soup bowl and keeping dirty air from car emissions and other pollutants from escaping.
Federal safe air standards are set at 35 micrograms of particles per cubic meter of air -- about the weight of a single crystal of table salt -- averaged over a 24-hour period. During inversions last month, Salt Lake County reached 69 micrograms per cubic meter, while nearby Utah County got to 125 micrograms, Mr. Bird said.
"If the 40,000 women in Utah who are pregnant suddenly started smoking, that would constitute a genuine health emergency," said Dr. Brian Moench, an anesthesiologist who leads Utah Physicians for a Healthy Environment, a group that has urged Gov. Gary R. Herbert, a Republican, to declare a public health emergency. "But our levels of air pollution are causing the exact same consequences as if all these women were smoking."
Air pollution is harmful to everyone, even if they do not show symptoms, Dr. Moench said, and the effects of the inversions can raise blood pressure and shorten life expectancy.
These days, the term "inversion" has been woven into Utahans' vernacular, and it is not uncommon to see commuters wearing masks on bad-air days.
Heather McCartin moved to Salt Lake City two years ago and bought a mask as soon she got here.
A 28-year-old student, Ms. McCartin suffers from cystic fibrosis and immediately felt the effects from the air.
"My asthma flares up -- it feels like I can't take a deep breath," she said. "It's definitely something I find a little ironic. As someone who cares so much about my health and my lungs, I ended up in a city that I absolutely love, and we sometimes have the worst air in the country."
Recently, Ms. McCartin and a group of friends ordered more masks, reflecting the growing concern with air quality.
In an interview on Thursday, Governor Herbert said the state had taken a number of steps to address the pollution: urging people to take mass transit, meeting with energy companies to develop emission reduction plans and reducing the use of state vehicles.
"I am very concerned about the air quality; we're doing everything we can to make sure it is improving, and in fact, it is," Mr. Herbert said, adding that the region had experienced more days that exceeded federal air standards in previous years. "Our air quality is much cleaner than it was. We've also had tremendous growth, and that compounds the problem."
It is not only people with health problems who notice the inversions. State Representative Patrice M. Arent of Millcreek was recently prescribed an inhaler because she found herself having trouble breathing.
Ms. Arent said she had been inundated with e-mail from constituents complaining about the air quality.
She and other Democratic lawmakers plan on introducing legislation that, among other things, would make regional public transportation free during January and July, the two months when air quality is typically at its worst (January because of the inversions, and July because of increased ozone levels due to heat and emissions), and would require all state agencies to develop plans to reduce activities that cause air pollution.
"I wish there was some easy solution, but there's not," Ms. Arent said. "The longer we delay, the harder it gets to clean up our air."
This article originally appeared in The New York Times.