Teaming Up to Fight PM2.5 Pollution: Sino-Japanese Research into Causes, Ways to Counter It
[2015.12.02] Read in: 日本語 | 简体字 | 繁體字 |

On October 1, 2015, a public seminar took place in the Nippon Foundation Building in Tokyo with the aim of shedding light on air pollution caused by particulate matter with a diameter of 2.5 micrometers or less, and seeking the possibility of Sino-Japanese cooperation on the issue. The seminar was organized by the Sasakawa Japan-China Friendship Fund as the first phase of a joint research project launched this year involving Japanese and Chinese universities and corporations. Experts from both countries gave talks on PM2.5 air pollution, which is a widespread problem in China.

Elusive Mechanism of PM2.5 Formation

Wakamatsu Shinji, president of the Japan Society for Atmospheric Environment and professor at the Ehime University Faculty of Agriculture.

Fine particulate matter smaller than 2.5 micrometers in size is a factor in serious air pollution that has become a particular problem in China and ultimately across the sea in Japan too. This year the Sasakawa Japan-China Friendship Fund launched a joint project seeking to find the causes of the high concentrations of PM2.5 that are often seen in wintertime and to propose countermeasures. The project, which involves Japanese and Chinese universities and corporations, aims to improve the quality of life in Japan and China and boost bilateral relations. At an October seminar, Professor He Kebin, dean of the Tsinghua University School of Environment, which has been monitoring PM2.5 levels in northern China centering on Beijing and Tianjin, reported mainly on the latest developments in China. Meanwhile, Professor Wakamatsu Shinji of the Ehime University Faculty of Agriculture discussed the past efforts and future plans of the Japan Society for Atmospheric Environment. The society, of which Wakamatsu is president, will be responsible for analyzing observed data and putting together the final proposal.

The governments of Japan and China, together with that of South Korea, adopted a five-year joint action plan at a tripartite meeting of environment ministers held in April 2015. Projects for intercity coordination and cooperation are already under way involving the cities of Kitakyūshū, Yokkaichi, and Kawasaki and prefectures including Hyōgo, Fukuoka, Nagano, and Saitama on the Japanese side and their counterparts in China. In the projects, participating municipalities work together in such areas as analysis of the factors generating air pollution, forecasting and prediction, and analysis of the sources of pollution. Private-sector efforts are taking place as well, such as the Japan-China Comprehensive Energy Conservation and Environment Forum. Launched in 2006 by the Japan-China Economic Association as a platform for promoting cooperation projects between Japanese and Chinese corporations, the forum has led to a total of 259 projects, including 41 in 2014; it was not held in 2013 due to tense bilateral relations.

Since Japan stopped providing yen loans to China in 2008, however, large-scale model projects have also ceased. The SJCFF joint research project is significant in that regard, as it endeavors to propose the formulation of effective and realistic measures against PM2.5, the causes of which are still poorly understood, and support various activities in the environmental field.

Seasonal Changes in Occurrence Patterns

According to He, there are seasonal patterns for PM2.5, with high concentrations being observed at night during the winter. Levels also fluctuate over the course of the day. The fine particles do not directly originate from motor vehicles and factories; they are formed secondarily as a result of chemical reactions between diverse substances. The phenomenon is seen over a large area in China, including Beijing and Tianjin. It is therefore important, Professor He stressed, to scientifically clarify the unique mechanism in China and come up with a reasonable set of measures that covers a wide geographic area, rather than dealing with each city separately.

Meanwhile in Japan, as Wakamatsu explained, the JSAE issued an emergency statement titled “The JSAE’s Approach to the PM2.5 Air Pollution Problem in China” in February 2013 in response to the massive scale of particulate pollution in China. “By cooperating internationally,” the society concluded, “we hope to accelerate research on this serious and unprecedented air pollution problem and, based on the scientific knowledge acquired through research, take a multifaceted approach toward tackling it.”

With regard to joint research with China on PM2.5, bilateral talks on model cities began after a “Japan-China Environmental Model Cities Plan” was proposed during a summit meeting between the two countries in 1997. The outcomes of joint research received high evaluations in 2004 and 2009. But despite these efforts, “There were severe cases of pollution in Beijing in 2013,” Wakamatsu said at the beginning of his lecture. He expressed his regret that the studies did not serve to circumvent large-scale pollution.

Wakamatsu went on to explain that some of the substances contributing to PM2.5 formation are of human origin, such as factories and cars, while others are of natural origin, such as volcanoes and yellow dust. The combination of these substances with meteorological factors—including amount of solar radiation, wind direction and speed, temperature, and humidity—gives rise to fine particulate matter. The formation process is further complicated by the addition of seasonal factors, such as low temperatures and light winds in winter and yellow dust and photochemical pollution in spring.

The JSAE’s emergency statement likewise described PM2.5 as “a highly complex phenomenon of air pollution in which gaseous matter and particulate matter emitted from diverse sources react and change their composition in the atmosphere.” Several hundred or more chemical substances may be involved, it said.

Past studies have made clear that PM2.5 is formed through highly different processes in summer and winter. The particulates are mostly the product of secondary formation in summer, while they are generated at night during the winter. Moreover, international comparisons between cities have revealed that the severity of the phenomenon in China is on an entirely different scale than what is seen elsewhere, in terms of both the extent and duration of episodes.

Learning Again From Japan

The seminar ended with closing remarks by Jia Die, deputy director of the China Youth Center for International Personnel Exchanges. His words were powerful.

Recalling his memories of being involved as a kind of guide in the 1972 restoration of diplomatic relations, Jia remarked that peace, friendship, and cooperation between the two countries have brought “invaluable benefits” to the people of both countries. He talked of how Japan began engaging in environmental conservation in the 1970s and when he visited Japan then, there was severe pollution in Tokyo. “But today the air is clean, and Japan’s beautiful environment is the object of envy. We would like to once again learn from Japan. It is my hope that China and Japan will contribute to the lives of both peoples by further stepping up exchanges and cooperation in the area of environmental conservation.” Jia spoke these words with great emotion, and many members of the audience could not help but think about the often troubled Sino-Japanese relationship of recent years.

Peace, friendship, and cooperation between the two countries have brought “invaluable benefits” to the people of both countries, said Jia Die, deputy director of the China Youth Center for International Personnel Exchanges, in his closing remarks.

According to the secretariat of the SJCFF, the research project will culminate in a proposal for measures to alleviate the high levels of PM2.5 pollution based on the results of research over the next two years. During this period, joint study meetings will be held as needed to review the results of monitoring and analysis, and propose necessary measures to alleviate the phenomenon. Proposed measures will be shared through public seminars, papers, and other means. They will also be submitted to both governments.

In September 2015 the JSAE signed a memorandum on academic exchange with its Chinese counterpart, the Atmospheric Environment Subcommittee of the Chinese Society for Environmental Sciences. The parties are planning an international symposium between Japan, China, and South Korea to coincide with the subcommittee’s annual meeting, scheduled to take place from December 6 to 8.

(Originally written in Japanese by Miki Takajirō of the editorial department and published on November 11, 2015. Banner photo: He Kebin, dean of the Tsinghua University School of Environment. All photographs courtesy of the Sasakawa Japan-China Friendship Fund.)

  • [2015.12.02]
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