ULAN BATOR, Dec. 27 (Xinhua) -- The Mongolian capital city of Ulan Bator on Wednesday saw solid particles in the air reaching dangerous levels, with the most-polluted area registering an amount almost 13 times above the safety level set by the World Health Organization (WTO).

There were "catastrophic pollution" at five locations in Ulan Bator, including the Bayankhoshuu slum district at 898 mg per cubic meter, and the Tolgoit slum district at 513 mg per cubic meter, according to the country's national agency for for meteorology and environment monitoring.

The city is no stranger to severe air pollution during winter in the past two decades, given its unfavorable meteorological conditions for pollutants to dissipate, and the heavy-dependence on coal in the large Ger areas surrounding the metropolitan region.

More than 800,000 residents, over half of Ulan Bator's population, live in Ger districts. Most of them came from provinces to find a job in the capital city of Mongolia.

Tight on money, some of them burn plastics and old tires to stay warm and to cook their meals during the long winter.

Since 2000, the Mongolian government, supported by various international organizations including the World Bank and the Asian Development Bank, has spent millions of dollars on programs to reduce air pollution.