Thirteenth century Mongol conqueror Genghis Khan worshiped the sky as a god and declared it the source of power as his hordes built the world's most expansive empire. In the last few years, however, smog and ash have increasingly blotted out the sky here in modern Mongolia's capital.
Coal-fired power plants and the exhaust from the growing number of motor vehicles on Ulan Bator's roads are viewed as the chief culprits, as they are from Beijing to New Delhi. But Ulan Bator's woes are exacerbated by a uniquely Mongolian factor: the tens of thousands of gers, or yurts, clustered around the city's edges.
For centuries, Mongolia's nomads have dwelt in these tent-like structures made of felt. But the promise of a better education and jobs has lured hundreds of thousands to the big city. Ulan Bator has 1.3 million residents — almost half the country's population — and gers have proliferated as a cheap and familiar form of housing. With no access to the city's central heating grid, though, ger dwellers must burn coal to stay warm.
And burn they do. Ulan Bator is the world's coldest capital; in January, the average low temperature was 41.3 degrees below zero, with the mercury once sinking to minus 86.8. Winter weather lingers through April, so clouds of smoke choke the skies for months on end. Ulan Bator means "red hero" in Mongolian, but the pollution is so bad that cynical locals have taken to calling their city Smoky Hero.
"It's really difficult to breathe and the smoke sticks to my clothes," says Tsetsegmaa Tsoggerel, a 23-year-old shop clerk. "Everything smells and I hate it."
Tsoggerel saves money by living in a ger. She bought the structure for $1,500 and pays $25 a month to lease the spot it sits on; a typical one-bedroom apartment rents for about $350 a month. But she worries about the long-term cost to her health and that of her husky puppy, Hero.
"When people sneeze or get rashes, they say they have allergies, but I don't think that's it. I think it's the pollution," she said.
Mongolia, landlocked between Russia and China, became a democracy about 25 years ago after decades as a Soviet satellite. In recent years, its economy has soared as foreign mining companies have been invited to tap the nation's rich deposits of valuable minerals, helping gross domestic product to grow nearly tenfold from 2000 to 2012. Though the economy has slowed, growth continued at a robust 7.8% last year.
The capital, which sits in a valley with mountains on the outskirts, was prone to bad air seasonally even before the economy started booming. Spring dust storms are common, whipping particles into the air and contributing to health problems such as eye infections.
The booming economy has brought thousands of foreigners to Mongolia, including about 2,000 Americans. For their sake as well as to address concern about the global effect of air pollution, the U.S. Embassy here recently began measuring Ulan Bator's air quality at its location in the heart of the city.
Following the lead of American Embassy officials in Beijing — who launched a monitoring program more than five years ago — U.S. diplomatic outposts have begun measuring air quality in Mongolia and other Asian nations, including Vietnam. By this summer, data will be posted and archived for research at a website run by the Environmental Protection Agency.
Ulan Bator has four air-monitoring stations run by the city's air quality department. But the U.S. Embassy is even closer to the central business district and parliament. "Ulan Bator is located in sort of a depression, and the embassy within that pocket is in one of the deepest parts of the city," U.S. Ambassador Piper Campbell said.
Unlike in Beijing, where the monitoring program has been perceived by Chinese leaders as a stick in the eye, the American efforts in Ulan Bator have been welcomed by the government and researchers, she said.
The typical level of tiny particulates known as PM 2.5 in Ulan Bator's air is about three times the level recommended by the World Health Organization, said Luvsan Munkh-Erdene, director of the health policy research center at the Mongolian National University of Medical Sciences. On bad days, it can climb to 12 times the WHO-recommended limit.
Air pollution here is of particular concern to pregnant women and children. Infants and youngsters growing up in ger districts are most at risk, said Munkh-Erdene, who has researched air quality in Ulan Bator and its effect on health for four years. Pneumonia is the most common immediate problem, and long-term exposure can contribute to cardiovascular disease and lung cancer.
Air pollution in Ulan Bator causes 130 premature deaths among children and 1,440 among adults each year, according to a 2014 report Munkh-Erdene researched with collaborators from UC Berkeley.
The government has subsidized and distributed more efficient stoves that produce less smoke. But foreigners in Ulan Bator sense little improvement.
"After a year or two, many expats give up," said Harris Kupperman, an American who heads the commercial real estate rental and development firm Mongolia Growth Group.
Kupperman, who lives much of the year in Miami, removed residential property rentals from his company's business portfolio after many foreign residents broke their leases and decided to leave the country. "There's lots of places with cold weather in the world, but Mongolia is special because of the pollution," he said.
Ulan Bator leaders want to dismantle the gers and wooden houses. They have long envisioned building affordable apartment complexes, with access to the city's heat and water services. That's still years away, however, and doesn't look like an option for Tsoggerel.
She imagines she'll eventually flee to a rural town, as her grandmother did eight years ago.
"I thought I would always just live in the city," she said, "but I don't know how I can keep living here."
Edwards is a special correspondent.