With thousands of families burning coal to survive in arctic temperatures, Mongolia is now home to the most poisonous air on the planet.

For Baasanjargal Batbaatar, a single mother of four, coal brings the only warmth they can afford. But it's coming at a price.

"The first time I almost lost my daughter was last winter. I went to the next room to feed my son and when I returned, she was suffocating. Her eyes rolled back. The diagnosis: asthma," Batbaatar said.

The hazardous haze is mainly caused by household stoves making Mongolia's air pollution up to 80 times the World Health Organization's safe limit.

Children and newborns are worst hit.

"A recent study indicated that during the winter of 2014-2015, there was a five-fold increase in the rate of still-births, with a near perfect correlation to air pollution," said Alex Heikens, resident representative of UNICEF in Mongolia.