AbstractThis introduction provides an overview and analysis of key scientific data regarding air pollution in China. It constitutes a reference for understanding how policymakers, media and population in China make sense of and deal with air pollution, as discussed in the other articles of the section. We summarize the major characteristics and trends regarding air pollution in China, including its main sources and composition, levels of population exposure across the country, attributable mortality, and mitigation efforts. We also compare current levels of air pollution in China with other parts of the world and in a historical perspective. While the situation remains dire in many regions, particularly the Northeast, we conclude that there are signs of relief, or at least a halt to the increase in ambient air pollution levels. At the same time, critical issues regarding unequal levels of exposure remain, and health damaging levels of air pollution in cities will undoubtedly remain high for a long time to come. The rural population residing in areas close to industry and polluted cities and still depending on solid household fuels will likely be the worst off when it comes to air pollution exposure.
Air pollution in Chinese cities has become a major topic of public debate and political concern. At the same time, few rural areas are subjected to measurements of ambient air quality, and policy documents and media rarely discuss the health and environmental risks caused by household air pollution (HAP) produced by the use of biomass for cooking and heating. Between 2014 and 2017 a cross-disciplinary team carried out a joint study of air quality and perceptions of air pollution in one of China's richest provinces, Zhejiang. We found that the ambient PM2.5 concentration in the rural villages was similar to that in the urban areas. Moreover, the 24-hour mean personal exposure to particulate pollution (PM2.5) was similar for urban and rural participants in total. However, we found indications of enhanced exposure levels in certain sub-groups, such as biomass users, women, and family cooks. We found that while villagers were strongly concerned about risks of air pollution coming from nearby factories, they were largely unaware of the problem of HAP. In this article, we analyse to what extent HAP contributes to the air pollution exposure in the areas studied, and we discuss possible reasons why it has largely remained a hidden hazard. In the conclusion, we suggest that air pollution in rural areas should receive more attention from media, environmental organizations and policy makers; furthermore, that HAP in particular should be incorporated into air pollution policies to a greater extent, and its contribution to air pollution exposure in rural areas be made more publicly known.
The increasing ozone (O 3 ) pollution and high fraction of secondary organic aerosols (SOA) in fine particle mass highlighted the importance of volatile organic compounds (VOCs) in air pollution control. In this work, a campaign of comprehensive field observations was conducted at an urban site in Beijing, from December 2018 to November 2019, to identify the composition, sources, and secondary transformation potential of VOCs. The total mixing ratio of the 95 quantified VOCs (TVOC) observed in this study ranged from 5.5–118.7 ppbv with the mean value of 34.9 ppbv, and the contemporaneous mixing ratios of TVOC was significantly lower than those observed in 2014 and 2016, confirming the effectiveness of VOCs emission control measures in Beijing in recent years. Alkanes, OVOCs and halocarbons were the dominant chemical groups, accounting for 75–81 % of the TVOCs across the sampling months. High and low-O 3 /PM 2.5 months as well as several O 3 /PM 2.5 polluted days were identified during the sampling period. By deweathered calculation, we found that high O 3 /PM 2.5 levels were due to both enhanced precursor emission levels and meteorological conditions favorable to O 3 and PM 2.5 production. The molar ratios of VOCs to NO X indicated that O 3 formation was limited by VOCs during the whole sampling period. Diesel exhaust and industrial emission were identified as the major VOCs sources on both O 3 -polluted and PM 2.5 -polluted days based on positive matrix factorization (PMF) analysis, accounting for 46 % and 53 %, respectively. Moreover, higher proportion of oil/gas evaporation was observed on O 3 -polluted days (18 %) than that on O 3 -clean days (13 %), and higher proportion of coal/biomass combustion was observed on PM 2.5 -polluted days (18 %) than that on PM 2.5 -clean days (13 %). On the base of O 3 formation impact, VOCs from fuel evaporation and diesel exhaust particularly toluene, xylenes, trans-2-butene, acrolein, methyl methacrylate, vinyl acetate, 1-butene and 1-hexene were the main contributors, illustrating the necessity of conducting emission controls on these pollution sources and species for alleviating O 3 pollution. Instead, VOCs from diesel exhaust and coal/biomass combustion were found to be the dominant contributors for secondary organic aerosol formation potential (SOAFP), particularly the VOC species of toluene, 1-hexene, xylenes, ethylbenzene and styrene, and top priority should be given to these for the alleviation of haze pollution. The positive matrix factorization (PSCF) analysis showed that O 3 and PM 2.5 pollution was mainly affected by local emissions. This study provides insights for government to formulate effective VOCs control measures for air pollution in Beijing.
The ambient air quality of Guangzhou in 2016 has significantly improved since Guangzhou and its surrounding cities implemented a series of air pollution control measures from 2014 to 2016. This study not only estimated the effects of meteorology and emission control measures on air quality improvement in Guangzhou but also assessed the contributions of emissions reduction from various sources through the combination of observation data and simulation results from Weather Research and Forecasting - Community Multiscale Air Quality (WRF-CMAQ) modeling system. Results showed that the favorable meteorological conditions in 2016 alleviated the air pollution. Compared to change in meteorology, implementing emission control measures in Guangzhou and surrounding cities was more beneficial for air quality improvement, and it could reduce the concentrations of SO(2), NO(2), PM(2.5), PM(10), and O(3) by 9.7 μg m(−3) (48.4%), 9.2 μg m(−3) (17.7%), 7.7 μg m(−3) (14.6%), 9.7 μg m(−3) (13.4%), and 12.0 μg m(−3) (7.7%), respectively. Furthermore, emission control measures that implemented in Guangzhou contributed most to the concentration reduction of SO(2), NO(2), PM(2.5), and PM(10) (46.0% for SO(2), 15.2% for NO(2), 9.4% for PM(2.5), and 9.1% for PM(10)), and it increased O(3) concentration by 2.4%. With respect to the individual contributions of source emissions reduction, power sector emissions reduction showed the greatest contribution in reducing the concentrations of SO(2), NO(2), PM(2.5), and PM(10) due to the implementation of Ultra-Clean control technology. As for O(3) mitigation, VOCs product-related source emissions reduction was most effective, and followed by transportation source emissions reduction, while the reductions of power sector, industrial boiler, and industrial process source might not be as effective. Our findings provide scientific advice for the Guangzhou government to formulate air pollution prevention and control policies in the future.
To tackle the severe fine particle (PM2.5) pollution in China, the government has implemented stringent control policies mainly on power plants, industry, and transportation since 2005, but estimates of the effectiveness of the policy and the temporal trends in health impacts are subject to large uncertainties. By adopting an integrated approach that combines chemical transport simulation, ambient/household exposure evaluation, and health-impact assessment, we find that the integrated population-weighted exposure to PM2.5 (IPWE) decreased by 47% (95% confidence interval, 37-55%) from 2005 [180 (146-219) μg/m3] to 2015 [96 (83-111) μg/m3]. Unexpectedly, 90% (86-93%) of such reduction is attributed to reduced household solid-fuel use, primarily resulting from rapid urbanization and improved incomes rather than specific control policies. The IPWE due to household fuels for both cooking and heating decreased, but the impact of cooking is significantly larger. The reduced household-related IPWE is estimated to avoid 0.40 (0.25-0.57) million premature deaths annually, accounting for 33% of the PM2.5-induced mortality in 2015. The IPWE would be further reduced by 63% (57-68%) if the remaining household solid fuels were replaced by clean fuels, which would avoid an additional 0.51 (0.40-0.64) million premature deaths. Such a transition to clean fuels, especially for heating, requires technology innovation and policy support to overcome the barriers of high cost of distribution systems, as is recently being attempted in the Beijing-Tianjin-Hebei area. We suggest that household-fuel use be more highly prioritized in national control policies, considering its effects on PM2.5 exposures.
To tackle the severe fine particle (PM2.5) pollution in China, the government has implemented stringent control policies mainly on power plants, industry, and transportation since 2005, but estimates of the effectiveness of the policy and the temporal trends in health impacts are subject to large uncertainties. By adopting an integrated approach that combines chemical transport simulation, ambient/household exposure evaluation, and health-impact assessment, we find that the integrated population-weighted exposure to PM2.5 (IPWE) decreased by 47% (95% confidence interval, 37-55%) from 2005 [180 (146-219) μg/m3] to 2015 [96 (83-111) μg/m3]. Unexpectedly, 90% (86-93%) of such reduction is attributed to reduced household solid-fuel use, primarily resulting from rapid urbanization and improved incomes rather than specific control policies. The IPWE due to household fuels for both cooking and heating decreased, but the impact of cooking is significantly larger. The reduced household-related IPWE is estimated to avoid 0.40 (0.25-0.57) million premature deaths annually, accounting for 33% of the PM2.5-induced mortality in 2015. The IPWE would be further reduced by 63% (57-68%) if the remaining household solid fuels were replaced by clean fuels, which would avoid an additional 0.51 (0.40-0.64) million premature deaths. Such a transition to clean fuels, especially for heating, requires technology innovation and policy support to overcome the barriers of high cost of distribution systems, as is recently being attempted in the Beijing-Tianjin-Hebei area. We suggest that household-fuel use be more highly prioritized in national control policies, considering its effects on PM2.5 exposures.
To tackle the severe fine particle (PM_(2.5)) pollution in China, the government has implemented stringent control policies mainly on power plants, industry, and transportation since 2005, but estimates of the effectiveness of the policy and the temporal trends in health impacts are subject to large uncertainties. By adopting an integrated approach that combines chemical transport simulation, ambient/household exposure evaluation, and health-impact assessment, we find that the integrated population-weighted exposure to PM_(2.5) (IPWE) decreased by 47% (95% confidence interval, 37–55%) from 2005 [180 (146–219) μg/m^3] to 2015 [96 (83–111) μg/m^3]. Unexpectedly, 90% (86–93%) of such reduction is attributed to reduced household solid-fuel use, primarily resulting from rapid urbanization and improved incomes rather than specific control policies. The IPWE due to household fuels for both cooking and heating decreased, but the impact of cooking is significantly larger. The reduced household-related IPWE is estimated to avoid 0.40 (0.25–0.57) million premature deaths annually, accounting for 33% of the PM_(2.5)-induced mortality in 2015. The IPWE would be further reduced by 63% (57–68%) if the remaining household solid fuels were replaced by clean fuels, which would avoid an additional 0.51 (0.40–0.64) million premature deaths. Such a transition to clean fuels, especially for heating, requires technology innovation and policy support to overcome the barriers of high cost of distribution systems, as is recently being attempted in the Beijing–Tianjin–Hebei area. We suggest that household-fuel use be more highly prioritized in national control policies, considering its effects on PM_(2.5) exposures.
