On July 26, Assistant Professor Geng Guannan from Professor He Kebin's research group at SOE, in collaboration with Professor Zhang Qiang from the Department of Earth System Science of Tsinghua University, published a paper about the drivers of PM2.5 air pollution and its health impact in China during 2002-2017. The study systematically quantified the relative influence of eight different factors on PM2.5-related deaths in China from 2002 to 2017, including economic growth, end-of-pipe control policy, energy-climate policy, economic structure, interannual meteorological variation, population growth, population ageing and improved health care.
PM2.5 levels in China now far exceeds the WHO guidelines, thus posing a serious threat to public health. Since many natural and anthropogenic factors contribute to the pollution, clarifying the drivers of PM2.5 air pollution is a common concern for the scientific community and policymakers, which is of great significance for analyzing the causes of pollution and formulating effective control strategies. Among the natural factors, meteorological conditions are an important one, and the interannual variation of meteorological conditions may have a non-negligible impact on the long-term trends of PM2.5 concentrations. In terms of the anthropogenic factors, economic growth leads to an increase in fossil fuel consumption, which exacerbates PM2.5 air pollution. On the other hand, a series of policies implemented by the government to improve energy efficiency and optimize energy structure, and the end-of-pipe control measures can reduce pollutant emissions and mitigate PM2.5 pollution. In addition, the health impacts attributed to PM2.5 pollution is also influenced by social factors such as population aging and medical conditions. Therefore, the long-term trends in PM2.5 pollution and its health effects are the results of the combined effects of the above-mentioned natural and anthropogenic factors. The contribution of some of these factors has been quantified in previous studies, but a comprehensive understanding of the effects of various natural and anthropogenic factors on PM2.5 pollution and its health impact calls for a deeper coupling between natural sciences and social sciences, which has been a challenge for a long time.
To address the above problems, the research group designed an interdisciplinary modeling framework, including atmospheric science, environmental science, economics, etc. Through the coupling of emission inventory model, decomposition approach, GEOS-Chem transport model, and exposure-mortality model, the complex nonlinear correlation between socio-economic system and atmospheric environment system was revealed. For the first time, the contributions of eight major factors to the long-term PM2.5 pollution and its health effects in China were quantitatively decomposed.
Figure 1 Long-term trends and main drivers of PM2.5 exposure in China during 2002-2017
The study found that premature deaths associated with PM2.5 pollution in China increased by 23% between 2002 and 2017. Among all these factors, the surge in fossil fuels consumption brought by rapid economic growth was one of the leading factors for the increased mortality risk, contributing to 1.23 million increase in PM2.5-associated deaths. The implementation of end-of-pipe control policies avoided premature deaths of 870,000 people, offsetting about 70% of the incremental mortality risk due to economic growth. Energy-climate policies and changes in economic structure contributed significantly to air pollution improvement, avoiding premature deaths of 720,000 people. During 2002-2017, with the implementation of the Air Pollution Prevention and Control Action Plan, stronger measures were taken on end-of-pipe control and energy structure transformation, driving the inflection point of PM2.5-associated mortality decrease in China.
The study also found that the overall meteorological variation was unfavorable in this period, increasing 90,000 PM2.5 pollution-related deaths. As to population vulnerability, PM2.5 pollution had a much more severe impact on the health of the elderly. The total population growth and the aging process increased 1.09 million PM2.5-related deaths, while the improved medical conditions prevented 430,000 potential deaths.
Figure 2 Long-term trends and main drivers of PM2.5-related mortality in China during 2002-2017
The study is the first attempt to quantitatively assess the main drivers of the long-term PM2.5 air pollution and its health impacts in China. The findings provide important implications for China to formulate future air pollution prevention and control policies and continue to improve air quality. Although PM2.5 concentrations in China have decreased significantly in recent years, it still lags behind the WHO guidelines. In addition, the problem of ozone (O3) has become more prominent, so the synergistic control of PM2.5 and O3 is of great urgency. In addition, the aging problem has become more prominent and the population has become more vulnerable to air pollution. Therefore, more stringent measures are needed to keep the air clean and protect public health in the future.
As the process of air pollution control is going deeper, China's mitigation efforts in air pollutant emission have entered a more difficult phase, where the dividends of end-of-pipe control cannot be sustained and further emission reduction is increasingly challenging. The study found that the structural transformation measures during the implementation of the Air Pollution Prevention and Control Action Plan from 2012 to 2017 were an important factor in scaling down PM2.5 air pollution levels. In the context of the major strategic goals of reaching carbon peak and carbon neutrality, it is advised that we seek greater synergy between curbing pollution and cutting carbon emissions. Under this guideline, we should transit from end-of-pipe control to addressing the root causes of issues, release the pollution reduction potential in the restructuring of energy, industry, transport, and land use, accelerate the energy transition towards clean and low-carbon growth and promote sustainable air quality improvement in the long-run.
The research results were published online in Nature Geoscience with the title of “Drivers of PM2.5 air pollution deaths in China 2002–2017”. Geng Guannan, an assistant professor in the School of Environmental, and Zheng Yixuan, a Ph.D. graduate from the Department of Earth System Science and an assistant professor in Chinese Academy of Environmental Planning, are the first authors of the paper, and Professor Zhang Qiang of the Department of Earth System Science is the corresponding author. The research was supported by the National Natural Science Foundation of China.
Link to the paper：
