"Legal Daily" reporter dialogue with Beijing Normal University, postdoctoral researcher Mao Da.

Recently, Jilin, deputy mayor of Beijing Municipality, announced the results of Beijing’s improvement in air quality when attending the CPPCC thematic symposium. He also stated that the data released by the public was true and explained that the public’s perceptions and monitoring data are different. s reason. In the next step, Beijing must fight a tough battle to further improve air quality. It is necessary to further eliminate high-energy-consuming, high-pollution enterprises and sacrifice some GDP and fiscal revenue.

Prior to this, the second public comment on the "Ambient Air Quality Standard" ended, and PM2.5 was first included in the standard. Hao Jiming, an academician of the Chinese Academy of Engineering and a professor at Tsinghua University, publicly stated at the 7th Sino-U.S. Air Quality Seminar recently held that simply emphasizing PM2.5 emission reduction could not achieve the desired effect of regional air quality improvement and should be done well. The project pollutants work together to reduce emissions. To improve air quality, what pollutants should be controlled? In response, the reporter of the "Legal Daily" initiated a dialogue with Mao Da, a postdoctoral fellow of the School of Chemistry of Beijing Normal University, who has conducted in-depth research on the air pollutant dioxin.

dialogue

Reporter: In the recent period, the public’s attitude toward PM2.5 can be described as a change of color. However, some experts have suggested that the impact on human health of air pollutants is far more than PM2.5, and it also includes pollutants such as dioxins.

Mao Da: During this time, the high concentration of PM2.5 in the air of large cities in China has caused great public concern. However, atmospheric pollutants with serious health concerns are not only fine particulates, so the new national standards for air quality under development should comprehensively assess the environmental health risks of various atmospheric pollutants, including what the world calls persistent organic. Dioxins of pollutants.

Dioxin compounds are one of the strongest toxic pollutants known to date by humans. The results of a large number of animal experiments and human epidemiological studies show that the health effects of dioxins on the human body are all-round. It has been identified as having carcinogenicity, neurotoxicity, reproductive toxicity, developmental toxicity and teratogenicity, cardiovascular Toxicity, immunotoxicity, and can directly cause chloracne and liver diseases, as well as an endocrine disruptor. According to the recommendations of the World Health Organization, in order to ensure human health, individual dioxin daily intake is 1 to 4 pg (toxic equivalent) per kilogram of body weight, and the long-term goal is to be reduced to 1 picogram (toxic equivalent) per Kilograms below body weight.

Scientific research also shows that dioxins are almost ubiquitous in the environment and they accumulate and accumulate in various organisms. Therefore, dioxins can be ingested through various channels such as breathing, diet, and skin contact. Although most dioxins are absorbed by the body through dietary intake and digestive tracts, the high concentration of dioxins in the air also makes it possible for the body's daily intake to exceed the WHO's recommended value.

Reporter: It is understood that Yuan Shaodong, Director of the Environmental Protection Bureau of Dongguan City, Guangdong Province, revealed that this year will promote the construction of Dongguan City's environmental monitoring and control center and speed up the testing laboratories for PM 2.5, dioxins, radiation, persistent organic pollutants, and ecological environment. Construction. According to the current situation, what standards should be used to limit dioxin?

Mao Da: To protect the health of the public, many countries or regions in the world have already established standards for atmospheric dioxin concentration. Japan, which has learned the history of tragic public hazards, is no exception. As early as 1999, Japan’s “Special Implementation Law for Dioxin Countermeasures” set various environmental media including the maximum allowable concentration of dioxins in the atmosphere, soil, water bodies, and sediments. Its purpose was to enable Japanese nationals to The daily intake of dioxin is below the WHO's maximum recommended value of 4 pg (toxic equivalent) per kilogram of body weight. According to the law, the concentration of atmospheric dioxins in Japan cannot exceed 0.6 pg (toxic equivalent) per cubic meter.

Although Japan's atmospheric dioxin concentration limit is not the most stringent in the world (the standards of Ontario, Canada and Arizona, USA are 0.1 and 0.023 picograms per cubic meter, respectively), the environmental standards are for China's current dioxin. Pollution prevention and control work has special significance because the Ministry of Environmental Protection, the National Development and Reform Commission, and the National Energy Administration jointly issued the “Circular on Further Strengthening the Management of Environmental Impact Assessment of Biomass Power Generation Projects” in 2008, and notified the The "Technical Essentials" section of the "Essentials" section stipulates that the EIA entity shall evaluate and predict the impact of dioxin emissions from construction projects on the surrounding environmental quality by referring to the dioxin atmospheric concentration limits in Japan. This shows that, to a certain extent, the Chinese government recognizes that atmospheric dioxin concentrations reaching or exceeding 0.6 pg (toxic equivalents) per cubic metre will have a non-negligible impact on the environment and human health. Therefore, this value can be regarded as the maximum tolerable concentration of atmospheric dioxins.

Reporter: At present, what is the level of dioxin in the air in China?

Mao Da: If the reference value of the dioxin environmental impact as defined by the three sectors in 2008, ie, the atmospheric dioxin concentration limit in Japan, is used as a basic standard for evaluating air quality, China currently knows from known scientific research results, Beijing. The concentration of air dioxin in the three mega cities, Shanghai and Guangzhou, has approached or exceeded the safety line.

In 2008, a number of researchers from the Chinese Academy of Sciences' Research Center for Eco-Environment and the Hong Kong Baptist University published an article in the international academic magazine Atmospheric Environment, showing that dioxins in three districts of Beijing Atmospheric concentrations range from 0.018 to 0.644 picograms (toxic equivalents) per cubic meter with an average of 0.268 picograms (toxic equivalents) per cubic meter. This result shows that the average concentration of atmospheric dioxins in some areas of Beijing is already in the same order of magnitude as the maximum tolerance of 0.6 pg (toxic equivalent) per cubic meter, and in some cases still higher than this value.

In the same year, several researchers from the Guangzhou Institute of Geochemistry of the Chinese Academy of Sciences and Shanghai University published a paper on the concentration level of atmospheric dioxins in Shanghai in another international academic journal Chemosphere, pointing out that Jiading and Zhabei The average dioxin concentrations in the four regions of Pudong and Huangpu were 0.4971, 0.289, 0.1444, and 0.1432 picograms per cubic meter, respectively. The results also indicate that the average concentration of atmospheric dioxins in some areas of Shanghai has approached the maximum tolerance of 0.6 picograms (TE) per cubic meter.

The situation in Guangzhou is also not optimistic. According to the PhD thesis of Yu Liping of the Guangzhou Institute of Geochemistry of the Chinese Academy of Sciences in 2007, the average concentrations of dioxins in the atmosphere in the four districts of Huadu, Liwan, Tianhe, and Huangpu reached 0.1046, 0.4305, 0.1637, and 0.7693 picograms (toxic equivalents), respectively. Every cubic meter. This result not only shows that Guangzhou, on the whole, is facing the same level of atmospheric dioxin pollution as Beijing and Shanghai. Local industrial activity areas such as Huangpu even exceed the maximum tolerance of 0.6 pg (toxic equivalent) per cubic meter. value. It is worth noting that Yu Liping also estimated the daily dioxin intake of adults in Tianhe District as 1.1 lb (toxic equivalent) per kilogram of body weight through the exposure formula, and the daily intake of children in some seasons was as high as 4.3 picograms. (Toxic Equivalent) The latter exceeds WHO's recommended safety standards per kilogram of body weight.

Reporter: What are the sources of pollution that cause high levels of dioxin?

Mao Da: In fact, the above findings should not be surprising, because China’s large or large cities already have a variety of significant sources of dioxin emissions, including steel industry, renewable non-ferrous metals industry, waste incineration industry, paper industry, and A huge amount of car exhaust emissions. If these sources are not effectively controlled, high concentrations of dioxins will continue to be discharged, and their accumulation in the environment will become more and more serious, and human health risks will increase.

In addition, the big cities are not the only disaster areas that cause dioxin air pollution. Recently, a dioxin pollution lawsuit in a rural area of ​​Hai’an County, Jiangsu Province revealed that a local household waste incineration plant may cause dioxin pollution in the surrounding environment. According to field sampling tests by researchers of the Dalian Institute of Chemicals, Chinese Academy of Sciences, the average concentration of atmospheric dioxins within 1.5 km of the incineration plant during operation in 2008 reached 0.716 and 0.622 picograms (TCE) per cubic meter. Even reached 0.901 picograms (toxic equivalents) per cubic meter. This case illustrates that there are also obvious sources of dioxin pollution in rural areas, and their atmospheric dioxins concentrations may exceed the maximum tolerance of 0.6 pg (toxic equivalents) per cubic metre.

Reporter: Since the three departments already have technical requirements for the environmental assessment of dioxins, why did they also propose the inclusion of dioxins in the new air quality standards?

Mao Da: Although China's dioxin pollution monitoring and research work is still very weak in general, the above important scientific findings or findings are enough to show that atmospheric dioxin pollution is an unavoidable environmental and health problem, and its degree of risk It is no less than the pollution of particles. Therefore, the re-discussion and re-enactment of China's air quality standards that are currently triggered by PM2.5 must include dioxin and other pollutants that have been neglected but have equivalent hazards in their consideration. After all, the dioxin-related technical requirements for dioxin proposed by the three departments in 2008 are not national environmental standards. Their legal binding force is not only limited, but also applies only to the environmental impact assessment of biomass power generation projects and is not sufficient to be fully controlled. The basic legal protection of atmospheric dioxin pollution.

Reporter: Then, how should the new air quality standards limit dioxins?

Mao Da: As for how the new national standard should set the maximum limit of atmospheric dioxins concentration, the relevant departments should use the most reliable scientific research data as the basis to fully solicit opinions from all sectors of the community, while taking into account foreign experience, to give a maximum protection of the environment. With national health and safety standards. From the current situation, this standard must not be more stringent than Japan's 0.6 gram (toxic equivalent) per cubic meter. Because only stricter standards can ensure that the level of dioxin exposure of ordinary people, especially sensitive individuals such as pregnant women and children, should be lower than WHO's recommended value.