State-run Xinhua News Agency reported that the average PM2.5 density in Beijing from Nov. 15 to Dec. 31 increased by 75.9 percent year on year, citing a report from the Chinese capital's environment regulator.
As the city continued to witness smoggy days during the winter period because of high population and unfavorable weather, the Beijing government had issued red alerts twice.
"Pollution caused by heating systems is one significant factor, while high humidity and little wind are unfavorable weather conditions for the diffusion of pollutants," Zhang Dawei, Beijing Environmental Protection Bureau's municipal environmental monitoring center director, said.
Zhang also noted that during winter, thick fog and haze are not a rare occurrence in the city. "But the number of days with heavy pollution in Beijing has significantly decreased compared with the same period in previous years," he said.
According to the Ministry of Environmental Protection (MEP), the city failed to meet public expectations despite the general improvement of the city's air quality.
Data further shows that in 2015, the PM2.5 density in Beijing, Tianjin, and the Yangtze River Delta and the Pearl River Delta decreased by 10.4 percent, 11.7 percent and 19 percent, respectively.
Additionally, the PM10 density in 338 cities dropped by 7.4 percent year on year on the average. Meanwhile, the PM2.5 density decreased by 11.3 percent on average in 161 cities.
In line with the upcoming Spring Festival, the MEP has also urged local environmental officials to thoroughly prepare. During the yearly celebration, Chinese citizens set off firecrackers that often lead to heavier air pollution.
The ministry also called for the strict monitoring of the sales and use of firecrackers, asking local authorities to punish anyone who will violate the regulations for such products. This reminder is also part of the MEP's intensified efforts to curb pollution caused by firecrackers.