On October 23, 2020, Ulaanbaatar, Mongolia registered the worst air quality in the world according to IQAir AirVisual air quality index (AQI). Registering at an air quality index of 203, the city has average AQI readings between 100-200 since October 11. Despite a government ban on burning raw coal, the city still experienced a steep decline in air quality as colder nights have descended on the north Asian capital city.

The city topped Lahore, Pakistan; Delhi, India; Chengdu, China; and Belgrade Serbia, all cities with unhealthy air quality at the time the Mongolian capital city registered at 203. The AQI level was part of a live city ranking of 100 cities recorded around 8 PM Ulaanbaatar Time.

Pictured: Ranked listing of cities around the world and their AQIs on Friday, October 23. The time listed is 5AM PST.

Dangerously high air quality levels can have a direct impact on human health. Ulaanbaatar, Mongolia air pollution levels have registered as dangerous on the Air Quality Index (AQI):

• 101-150: Classified as “unhealthy for sensitive groups.” People most affected by poor air quality should limit their exertion outdoors.
• 151-200: Within this range, air quality is deemed “unhealthy,” a threat to sensitive demographics. It’s also harmful to the general public.
• 201-300: This AQI range is considered “very unhealthy,” and sensitive groups are encouraged to limit outdoor activities. There are health risks for anyone outdoors when air quality reaches this level.

Pictured: the IQAir AirVisual air quality index (AQI), based on US AQI standards per the Environmental Protection Agency (EPA)

Ulaanbaatar ranked 48th on the list of most polluted citiesfor PM2.5 (particulate matter with a diameter size of 2.5 microns or smaller) in 2019, with the worst air quality registered from January through March and October through December.Overnight temperatures in October, 2020 have dropped from a low of 20 degrees Fahrenheit on October 1st, just 4 degrees Fahrenheit on October 13th.¹

Mongolia ranked 3rd among reported nations in the IQAir 2019 World Air Quality Report, with an average PM2.5 concentration of 62micrograms per cubic meter (µg/m³) weighted by population, equating to an AQI of 154. PM2.5 concentration was 6 times above the World Health Organization (WHO) annual exposure recommendation of 10 µg/m³.

Pictured: Hourly air quality index (AQI) data for Ulaanbaatar, Mongolia from Thursday, September 24 to Friday morning, October 23rd.

Why does Mongolia have air pollution?

Ulaanbaatar’s poor air quality in winter is most frequently connected to Mongolia’s dominant heating practices in a city with some of the coldest winters of any world capital. Air pollution in Mongolia has been attributed in studies to seasonal solid fuel combustion.²

Raw coal is burned in city districts within traditional gers, portable circular one-room homes made from a wooden frame and felt. Stoves or boilers located in the center of the home send exhaust through a chimney and out a flap at the top of the dome.

Coal is preferred in winter due to the longer lasting burn provided in comparison to biomass materials such as dung or wood. Raw coal-burning in the gers is attributed as the city’s primary source of pollution. The WHO estimates that 80 percent of the city’s winter air pollution comes from the gers, where an estimated 60 percent of city dwellers reside.³

According to WHO health and environmental officer Dr Delgermaa Vanya, “the coal used in the stoves is a primary cause of Ulaanbaatar’s air pollution, much worse than other sources of pollution such as cars and trucks or waste burning.”

Other sources of regional air pollution include coal-fired power plants, dust from unpaved roads, and motor vehicle exhaust.

47 percent of the country’s population lives in Ulaanbaatar, up from around 27 percent in 1989.⁴ The city population has boomed, with an estimated 1.4 million people in 2018. Rural Mongolians have moved to Ulaanbaatar to find better jobs, living conditions, health services, education services, or for family. Increasingly harsh winters and severe droughts have taken their toll on migratory herding, as livestock may be lost or herders are forced to travel greater distances for pastureland, causing herders to move to the city for more stable work.

The Ger districts, found on the outskirts of the city, are largely off the grid due to a lack of infrastructure. Residents have been forced to make due without running water, sewage, central heating, and in some cases, electricity. Even those city migrants who have access to electricity still tend to use coal-, wood-, or dung-fired stoves for heating and cooking due to the lower cost.

Contributing to Ulaanbaatar’s struggle with air pollution is its location. The city was built in a valley, a geographic liability that’s led to a thermal inversion effect. Cool air and pollutants stay closer to the ground below, trapped by a layer of warmer air above.⁵Salt Lake City is prone to the same affect.

The Mongolian government began a ban on raw coal burning in May, 2019. Raw coal has generally been cheap and obtainable for the city’s poorer residents; keeping a ger warm and cooking meals when the external temperatures drop below freezing has been an essential priority. Recognizing the urgency to reduce air pollution and still permit essential household functions, the government has committed to expanding infrastructure. As a transitional step, the government distributed more fuel-efficient semicoke briquettes as an alternative to raw coal.

Poor air quality in Mongolia can lead to numerous health issues

Coal combustion creates PM2.5, an airborne pollutant measuring only ≤25 microns in diameter. Though tiny, they can do significant damage to the human system through inhalation. Coarse particles (PM10-2.5) can be irritants to the eyes, nose and throat.⁶ Finer particulates go deep into the lungs and heart, and bloodstream. Potential negative health impacts include:

• asthma aggravation
• respiratory symptoms
• increased hospitalizations
• increased mortality rates from cardiovascular and respiratory diseases
• lung cancer

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Those with pre-existing heart and lung conditions, the elderly, and children are considered most vulnerable to adverse health effects; children can struggle with reduced lung growth rate and long-term function.

Apart from creating high levels of PM2.5, raw coal burning also releases sulfur dioxide, nitrogen oxide, and carbon monoxide into the atmosphere.

The IQAir major city ranking features 100 major cities with a population of more than 300,000 people. Cities have been selected to represent a wide range of countries to allow global contrast. The ranking is updated hourly and is based on a comparative level of air quality across major cities at any given hour. To compare cities using their annual mean air quality levels, visit IQAir’s World’s Most Polluted Cities list.