Sep 07, 2021 09:01 PM

More Beijing Smog Blowing in From Outside, Report Shows

An increasing proportion of Beijing’s air pollution is blowing into the Chinese capital from other regions, though most of the city’s smog is still locally emitted, a new report shows.

The Monday report (link in Chinese), issued by Beijing’s ecological and environmental monitoring center, focused on PM2.5 emissions — ultrafine particles that can pass through the lungs into the bloodstream and damage organs in the body.

Over the period covered by the report — January 2020 to June this year — nearly 60% of Beijing’s PM2.5 pollution was emitted within the capital’s borders, down from 66% (link in Chinese) between January 2017 and May 2018. The remainder in both periods came from outside the city.


High-rise buildings in Beijing’s CBD area are shrouded in smog in October 2020. Photo: Jia Tianyong/China News Service,VCG

However, the proportion of local and regional pollution is inverted on the city’s most polluted days, the report found. On heavily smoggy days — those with a daily average concentration of 150 micrograms of PM2.5 per cubic meter of air — more than 60% of the pollution came from so-called regional transmission.

Since China declared a “war on pollution” in 2014, after decades of environmental damage amid rapid economic development, the capital’s air quality has been one of the most high-profile metrics of success.

Experts have suggested a long-term mechanism be established to allow regions to jointly work on air pollution prevention and control, while optimizing the regional industrial layout, the report said.

Beijing is mostly surrounded by Hebei province, a major center for heavy industry including a vast steel sector.

The report is based on research conducted by the Beijing Municipal Ecology and Environment Bureau, the city’s monitoring center, and several other institutions such as the prestigious Peking and Tsinghua universities, the director of the monitoring center was quoted by the state-run Xinhua News Agency as saying.

The report also looked at the various sources of locally generated PM2.5 in the city.


It showed that “mobile sources,” including emissions from diesel and gasoline vehicles, accounted for 46% of Beijing’s local PM2.5 emissions over the period, followed by “life-scenario” sources with 16%, and dust sources at 11%.

Life-scenario sources refer to emissions related to the “rigid operation” of the city, the services industry and residents, according to the report, which gave solvent use and auto repair as examples.

“Mobile sources are the largest source of PM2.5 at different times and spatial ranges throughout the year, which is similar to the (pollution) characteristics of developed cities around the world,” said the report.

The report also noted the life-scenario sources in Beijing rose from 12% of the total compared with the period from January 2017 to May 2018.

“‘Beijing blue’ has gradually become the new normal,” Huang Runqiu, head of the Ministry of Ecology and Environment, said at a press conference (link in Chinese) on Aug. 18, after the city reported its lowest monthly PM2.5 reading since 2013 in July.

In that month, Beijing’s average concentration of PM 2.5 was 16 micrograms. However this was still higher than the World Health Organization’s recommended limit of an annual average of 10 micrograms per cubic meter.

Huang also said that Beijing’s average PM2.5 concentration for 2020 was 38 micrograms per cubic meter, a decrease of 52.9% compared with 2015.

Contact reporter Wang Xintong ( and editor Joshua Dummer (

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