All general educational schools in the Mongolian capital of Ulan Bator will observe winter vacation during the peak season of air pollution, local media reported Friday, citing the country's education ministry.

According to the Ministry of Education, Culture, Science and Sports, all primary schools in the capital will observe winter vacation for a period of 49 days starting from Dec. 22.

Secondary and high schools will have a winter vacation lasting 42 days starting from Dec. 29.

The ministry's decision is a preventive measure to protect the health of students from air pollution.

Ulan Bator, the world's coldest capital in winter, suffers one of the world's heaviest levels of air pollution.

The city is also home to nearly half of the country's child population, who are found to have 40 percent poorer lung functions than those from rural areas.

More than 800,000 residents, over half of Ulan Bator's population, burn raw coal and other flammable materials, a major contributor (80 percent) to the city's air pollution.

Since the early 2000s, the Mongolian government, international donors and development organizations, including the World Bank and the Asian Development Bank, have spent millions of dollars combating air pollution in Ulan Bator.

However, the city has not seen a significant reduction in levels. The city's air pollution on Jan. 30 exceeded 133 times above the safety level set by the World Health Organization.