By Yereth Rosen

ANCHORAGE, Alaska (Reuters) - Santa may need more than Rudolph's bright nose to get through the grimy North Pole atmosphere.

North Pole, Alaska - the Fairbanks suburb, not the spot at the top of the globe - has posted some of the nation's worst air-quality readings in recent days, thanks to high levels of wood smoke streaming into stagnant cold air.

Concentrations of particulates have made North Pole's air "very unhealthy," meaning children, the elderly and other vulnerable people should stay indoors and all residents should refrain from prolonged exercise, according to local government officials.

The "very unhealthy" classification was given in the past few days. A search of airnow.gov - the government portal which monitors air quality - did not reveal any other U.S. community currently with such poor quality air.

The problem stems from residents' dependence on wood-burning stoves for heat in an extremely cold region prone to pollution-trapping temperature inversions, said officials with the Fairbanks North Star Borough, the regional government.

"As long as it's cold and the air is still, we have a particulate problem," said Jim McCormick, a technician with the borough's Air Quality Division.

With temperatures in some spots below minus-30 degrees Fahrenheit (-34.4 C) and no relief forecast until next week, the air is expected to stay dirty, McCormick said.

As of Friday, particulate pollution in North Pole was worse than in Beijing, which is notorious for chronic air pollution, a Fairbanks newspaper columnist reported, although Reuters was unable to verify the claim independently.

Dermot Cole of the Fairbanks News-Miner said his research found only one city in the world, Guangzhou in southern China, with particulate readings that are currently worse than those in North Pole.

Alaska's pristine, mountainous landscapes suggest crystal clean air. But the city of Fairbanks also has had recent problems, with air quality classified by the borough on Friday as "unhealthy" - not as dire as in North Pole, but still triggering warnings against outdoor activities.

The entire Fairbanks North Star Borough has been plagued for years with wintertime air pollution. It is consistently in violation of federal air-quality standards and is required under federal and state laws to come up with measures to clear the air, although they have proved elusive.

A local program that allowed residents to swap out old wood stoves for more efficient models was halted by an anti-regulation initiative that borough voters passed in October.

"That stopped it cold," McCormick said.

(Editing by Tim Gaynor and Vicki Allen)