Two million people are at risk from a toxicÂ fog that has descended over Utah as pollution levels in Salt Lake City reach anÂ all-time high.
The icy fog has smothered the Salt LakeÂ Valley for several weeks and trapped lung-busting soot emitted in the cityÂ underneath.
The level of pollution in the city is now theÂ highest in America according to theÂ Environmental Protection Agency andÂ medical experts are now urging residents to stay indoors.
The smog over Salt Lake City, which isÂ surrounded by the Wasatch and Oquirrh mountain ranges,Â has been caused byÂ a temperature inversion where warmer air has created a barrier above cold fog soÂ everything underneath is trapped.
Snow cover on the surrounding mountains hasÂ amplified the phenomena, leaving Salt Lake City at just 18 degrees while ParkÂ City basks in sunny 43-degree weather.
The warmer air aloft has acted like a lid onÂ the frigid valley air, leaving it with no place to go.
The pollution is now getting so bad that moreÂ than 100 Utah doctors are calling for authorities to immediately lower highwayÂ speed limits, curb industrial activity and make mass transit free for the restÂ of winter.
Doctors say the microscopic soot – aÂ showerÂ of combustion particles from tailpipe and other emissions – canÂ tax the lungsÂ of even healthy people.
‘We’reÂ in a public-health emergency forÂ much of the winter,’ said Brian Moench, aÂ 62-year-old anesthesiologistÂ and president of Utah Physicians for a HealthyÂ Environment, whichÂ delivered the petition demanding action at the Utah Capitol.
TheÂ greater Salt Lake region had up to 130 micrograms of soot per cubic meter – moreÂ than three times the federal clean-air limit, according to the U.S.Â Environmental Protection Agency.
And for two million Utah residents, there isÂ no escape from the fog, except to the snow-capped mountains surrounding the cityÂ or resort towns like Park City, where the Sundance Film Festival is under way.