Neighbouring regions are one of the major contributors to the Chinese capital's PM 2.5 pollution - particulate matter with a diameter less than 2.5 micrograms that can go deep into the lungs and is extremely harmful to health - according to recently updated research by the city's environmental watchdog.
As much as 28 per cent to 36 per cent of Beijing's PM 2.5 pollution is contributed by neighbouring regions, including Tianjin and Hebei province, according to the PM 2.5 source-identification study released by the Beijing Environmental Protection Bureau during a news briefing on Wednesday.
The study was jointly conducted by the bureau, the Beijing Environmental Protection Monitoring Center, the Chinese Research Academy of Environmental Sciences and Peking University, the bureau said.
Among the local culprits for the city's notorious smog, automobile exhaust contributes the most, accounting for 31.1 per cent of the emissions in the city, said Chen Tian, head of the bureau.
Monitoring stations by roadsides register an obviously higher PM 2.5 intensity compared with other monitors, mostly due to direct emissions from automobiles, which also stir up dust while driving, further worsening pollution, the bureau said.
As one of the areas hit hardest by smog, the Beijing-Tianjin-Hebei region has been conducting studies to identify the sources of PM 2.5.
Results on the pollution sources for Tianjin and Shijiazhuang of Hebei province will be released by June, and the Pearl River and Yangtze River delta areas as well as the rest of the cities in Hebei province will reach a conclusion of identified pollution sources by the end of this year, as required by the Ministry of Environmental Protection.
The study and analysis of what contributes to the atmospheric pollution will provide essential evidence for policymaking by the central government to deal with the hazy days, said Chen.
The analysis is a fundamental basis for Beijing's clean air action plan, he said.
According to the plan, more than 300 polluting industries will be shut down this year.