(Left) A ger on the city’s outskirts. (Right) A chimney in one ger sends the coal smoke out through the opening in the roof. In the past 20 years, 600,000 people have migrated to Ulaanbaatar — many occupying traditional gers off the city’s electric grid. They burn raw coal, garbage and other material to stay warm. Smokestacks feed a layer of smog that blankets the city.

(Left) A ger on the city’s outskirts. (Right) A chimney in one ger sends the coal smoke out through the opening in the roof. In the past 20 years, 600,000 people have migrated to Ulaanbaatar — many occupying traditional gers off the city’s electric grid. They burn raw coal, garbage and other material to stay warm. Smokestacks feed a layer of smog that blankets the cit