Pollution Like Snow: A Mongolian Winter

Summer is quickly drawing to a close in Mongolia’s capital, Ulaanbaatar, which means one thing: winter is coming—nearly six months of it. “UB,” as the city is commonly known, is the coldest capital city in the world with winter temperatures below -35 degrees Celsius. But the cold isn’t the only worry for the city. Winter also means the stubborn return of stifling air pollution largely absent during the warm summer months. Each winter UB’s nearly 1.5 million residents, roughly half Mongolia’s population, endure truly terrifying levels of ambient particulate matter.

“Air pollution now sounds like a part of the season to us, like snow,” Bat-Erdene Purevnyamjid, a resident who lives in central UB, told The Diplomat.

“In the mornings and evenings, in some parts of the city, it's even hard to see what's 20 or 30 meters away,” he said.

Beginning as early as October and extending through March, a thick, choking haze regularly occupies the narrow valley in which UB is nestled, obscuring buildings and enveloping entire neighborhoods in dark shrouds of ash.

“UB is one of the most polluted cities in the world,” said Dr. Ryan Allen, a researcher at Simon Fraser University in Canada, who has extensively studied the city’s air quality and its public health implications. The seasonal variation in UB is a unique characteristic that makes it different from other places more infamous for air pollution like Beijing or Delhi, Allen explained.

The annual average PM2.5, or fine particulate matter, concentration in Ulaanbaatar ranges between 70 and 200 micrograms per cubic meter (μg/m3), depending upon the precise location in the capital. Those levels are seven to 20 times higher than the World Health Organization’s (WHO) guidelines.

“That’s dramatically higher than what we’d like to see in order to protect public health,” said Allen.

“The air pollution in UB in the winter rivals anywhere in the world. At some points, the air is comparable to fighting a wildfire, say somewhere in California,” said Dr. Christa Hasenkopf, an atmospheric scientist who studied the city’s air pollution on a Fulbright Scholarship and, more recently, founded OpenAQ, a global open-source platform for public air quality data.

Once a sub-Siberian cold front sets in, UB’s outdoor air pollution can reach nightmarish magnitudes. In October 2015, air quality monitors in the Amgalan district recorded levels of PM10, particulate matter with a diameter of 10 microns or less, that reached 1,010 parts per cubic meter—a rate over 500 times the WHO guidelines. This February, levels of PM2.5, a smaller but deadlier particle that can become trapped in human lungs, hit 488 micrograms per cubic meter, nearly 50 times the WHO’s recommended limit. According to the World Bank, the average daily PM10 concentration at the highest-registering monitoring station in 2009 peaked at 4,360 micrograms per cubic meter—an almost unbelievable figure.

While outdoor air pollution in Beijing and Delhi consistently capture headlines, Ulaanbaatar doesn’t generally receive similar coverage, even though its average pollution levels are on par or worse than both Asian megacities’. According to the WHO’s 2014 data, Mongolia’s annual airborne particulate matter levels exceeded China’s and India’s on both a real and population-weighted basis.

“One of the things that makes UB unique -- and other places similar to UB that are smaller and face extremely severe air pollution levels -- is that they just fall completely off the radar,” said Hasenkopf.