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.”