Controlling air pollution will continue to be a priority for the Beijing municipal government in the coming year, with a decline expected in the concentration of fine airborne particles, the city's mayor said in a report.

The average density of PM2.5 - airborne particles smaller than 2.5 microns in diameter that can penetrate the lungs and harm health - is expected to decrease by 5 percent in Beijing next year due to continuing efforts such as controlling coal burning and vehicles' discharge of pollutants, Mayor Wang Anshun said on Wednesday while delivering a report on Beijing's economic and social development for this year.

Emission of carbon dioxide is expected to be cut by 2.5 percent next year, he said.

Density of PM2.5 for this year in Beijing was expected to be reduced to 85 micrograms per cubic meter, according to a plan released by the municipal government earlier this year. The fine particles are a major contributor to Beijing's smog.

According to an air pollution control plan released by the municipal government last year, the average density of PM2.5 in Beijing is expected to be about 60 micrograms per cubic meter in 2017, a quarter less than that of 2012.

In recent years, thick smog has become more common in Beijing and many other areas in China, causing complaints among the public.

In October, Beijing encountered a total of 10 days of serious pollution, with density of PM2.5 increasing by more than 77 percent over September, according to the Ministry of Environmental Protection.

High emissions of pollutants and a lack of wind were the major reasons for this, environmental protection authorities said.

The Beijing municipal government has taken a series of measures to combat pollution this year. To reduce pollution for the Asia-Pacific Economic Cooperation meetings that were held in Beijing last month, nearly 61,000 factories were asked to curb production in Beijing and neighboring areas during the meetings.

Beijing's daily PM2.5 density fell to 43 micrograms per cubic meter between Nov 1 and 12, dropping 55 percent year-on-year, which was the best for the same period in five years, according to the Ministry of Environmental Protection.

Compared with the major cities of some developed countries, Beijing faces an arduous task to control its pollution, as there are multiple major sources of pollutants, including coal and oil, said Ye Qian, a professor of meteorology and disaster relief at Beijing Normal University.

"In addition, urbanization is still in progress, and the city is becoming taller and larger, making it harder for pollutants to be dispersed," he said.