Estimated Contributions of Emissions Controls, Meteorological Factors, Population Growth, and Changes in Baseline Mortality to Reductions in Ambient [Formula: see text] and [Formula: see text]-Related Mortality in China, 2013-2017

Assessing the effectiveness of PM2.5 pollution control from the perspective of interprovincial transport and PM2.5 mitigation costs across China

Due to the transboundary nature of air pollutants, a province's efforts to improve air quality can reduce PM2.5 concentration in the surrounding area. The inter-provincial PM2.5 pollution transport could bring great challenges to related environmental management work, such as financial fund allocation and subsidy policy formulation. Herein, we examined the transport characteristics of PM2.5 pollution across provinces in 2013 and 2020 via chemical transport modeling and then monetized inter-provincial contributions of PM2.5 improvement based on pollutant emission control costs. We found that approximately 60% of the PM2.5 pollution was from local sources, while the remaining 40% originated from outside provinces. Furthermore, about 1011 billion RMB of provincial air pollutant abatement costs contributed to the PM2.5 concentration decline in other provinces during 2013-2020, accounting for 41.2% of the total abatement costs. Provinces with lower unit improvement costs for PM2.5, such as Jiangsu, Hebei, and Shandong, were major contributors, while Guangdong, Guangxi, and Fujian, bearing higher unit costs, were among the main beneficiaries. Our study identifies provinces that contribute to air quality improvement in other provinces, have high economic efficiency, and provide a quantitative framework for determining inter-provincial compensations. This study also reveals the uneven distribution of pollution abatement costs (PM2.5 improvement/abatement costs) due to transboundary PM2.5 transport, calling for adopting inter-provincial economic compensation policies. Such mechanisms ensure equitable cost-sharing and effective regional air quality management.

Spatially explicit analysis of production and consumption responsibility for the PM2.5-related health burden towards beautiful China

Promoting good health and ensuring responsible production and consumption are essential components of the Sustainable Development Goals (SDGs) established by of the United Nations, as well as the goals of beautiful China. While the health impacts of air pollution have garnered significant attention, there remains a paucity of studies comparing the disparities in responsibility arising from production versus consumption. This paper integrates the Weather Research and Forecasting - Comprehensive Air Quality Model with Extensions (WRF-CAMx) model, the multiregional input‒output (MRIO) model, and the global exposure mortality model (GEMM) to assess the extent of PM2.5-related premature deaths caused by production and consumption activities in 30 Chinese provinces. The findings reveal a spatial mismatch in health burdens between production and consumption. Considering pollutant emissions and their transfer only through the supply chain leads to the finding that the net outflow of emissions from producers is mainly located in most of the northern provinces of China. However, when atmospheric transport and health impacts are included, the producing provinces are mainly located in central China, while the consuming provinces are located in the southeastern coastal and remote western and northern regions. Additionally, the long-range impact of consumption provinces with respect to the health burden is more than twice as large as that of production provinces, and its potential impact on the health burden cannot be ignored. From a sectoral perspective, production emissions from the non-electricity industry and services sectors contribute to 60% of the health burden, while their consumption emissions contribute to over 80% of the health burden. Furthermore, consumption activities in the non-electricity industry and services sectors significantly influence production emissions in the transport, agriculture, and electricity sectors. The geographical separation of consumption and production regions facilitated by trade is a critical yet often overlooked aspect in current regional air quality planning in China. A more comprehensive analysis of life-cycle emissions driven by final consumption could yield greater reductions compared to direct production reductions.

Identifying Key Sources for Air Pollution and CO2 Emission Co-control in China

China is confronting the dual challenges of air pollution and climate change, mandating the co-control of air pollutants and CO2 emissions from their shared sources. Here we identify key sources for co-control that prioritize the mitigation of PM2.5-related health burdens, given the homogeneous impacts of CO2 emissions from various sources. By applying an integrated analysis framework that consists of a detailed emission inventory, a chemical transport model, a multisource fused dataset, and epidemiological concentration-response functions, we systematically evaluate the contribution of emissions from 390 sources (30 provinces and 13 socioeconomic sectors) to PM2.5-related health impacts and CO2 emissions, as well as the marginal health benefits of CO2 abatement across China. The estimated source-specific contributions exhibit substantial disparities, with the marginal benefits varying by 3 orders of magnitude. The rural residential, transportation, metal, and power and heating sectors emerge as pivotal sources for co-control, with regard to their relatively large marginal benefits or the sectoral total benefits. In addition, populous and heavily industrialized provinces such as Shandong and Henan are identified as the key regions for co-control. Our study highlights the significance of incorporating health benefits into formulating air pollution and carbon co-control strategies for improving the overall social welfare.

Unveiling the health impacts of air pollution transport in China

The transport of atmospheric pollutants plays a pivotal role in regional air pollution, highlighting critical concerns over the unequal health outcomes that arise from such transport. While previous researches predominantly focused on key areas in the battle against air pollution, the intensification of control measures necessitates a national perspective to comprehend the health impacts due to pollution transport. Our study establishes an integrated assessment framework that combine an emission-concentration response surface model with a health impact evaluation model to analyse the nationwide health impacts of PM2.5 and O3 pollution transport across China's 31 provinces. We found that, interprovincial transport of PM2.5 and O3 contributed to 747,000 and 110,000 deaths respectively in 2017, which amounts to 38% and 48% of deaths caused by total anthropogenic emissions. North, East, and Central China together contribute 82% and 69% to the health impacts caused by regional PM2.5 and O3 transport respectively, and the transport among these three regions is also significant. The analysis of interprovincial health impact transport shows that, for PM2.5, the top contributors are Hebei, Shandong, Henan, Anhui, and Jiangsu, with the most affected being Henan, Shandong, Jiangsu, Hebei, and Guangdong. Regarding O3, Shandong, Hebei, Henan, Jiangsu, and Anhui contribute the most, while Henan, Shandong, Hebei, Jiangsu, and Anhui are the most affected. This study can shed lights on regional control strategies by prioritizing control areas based on the health impact of air pollution transport in China.

Air Quality, Health, and Equity Benefits of Carbon Neutrality and Clean Air Pathways in China

In the pursuit of carbon neutrality, China's 2060 targets have been largely anchored in reducing greenhouse gas emissions, with less emphasis on the consequential benefits for air quality and public health. This study pivots to this critical nexus, exploring how China's carbon neutrality aligns with the World Health Organization's air quality guidelines (WHO AQG) regarding fine particulate matter (PM2.5) exposure. Coupling a technology-rich integrated assessment model, an emission-concentration response surface model, and exposure and health assessment, we find that decarbonization reduces sulfur dioxide (SO2), nitrogen oxides (NOx), and PM2.5 emissions by more than 90%; reduces nonmethane volatile organic compounds (NMVOCs) by more than 50%; and simultaneously reduces the disparities across regions. Critically, our analysis reveals that further targeted reductions in air pollutants, notably NH3 and non-energy-related NMVOCs, could bring most Chinese cities into attainment of WHO AQG for PM2.5 5 to 10 years earlier than the pathway focused solely on carbon neutrality. Thus, the integration of air pollution control measures into carbon neutrality strategies will present a significant opportunity for China to attain health and environmental equality.

Ozone Mortality Burden Changes Driven by Population Aging and Regional Inequity in China in 2013-2050

Air pollution exposure is closely linked to population age and socioeconomic status. Population aging and imbalance in regional economy are thus anticipated to have important implications on ozone (O3)-related health impacts. Here we provide a driver analysis for O3 mortality burden due to respiratory disease in China over 2013-2050 driven by population aging and regional inequity. Unexpectedly, we find that population aging is estimated to result in dramatic rises in annual O3 mortality burden in China; by 56, 101-137, and 298-485 thousand over the periods 2013-2020, 2020-2030, and 2030-2050, respectively. This reflects the exponential rise in baseline mortality rates with increasing age. The aging-induced mortality burden rise in 2030-2050 is surprisingly large, as it is comparable to the net national mortality burden due to O3 exposure in 2030 (359-399 thousand yr-1). The health impacts of O3 pollution, shown as mortality burden per capita, are inequitably distributed, with more severe effects in less developed provinces than their developed counterparts by 23.1% and 21.5% in 2019 and 2030, respectively. However, the regional inequity in O3 mortality burden is expected to be mitigated in 2050. This temporal variation reflects evolving demographic dividend characterized by a larger proportion of younger individuals in developed regions. These findings are critical for targeted improvement of healthcare services to ensure the sustainability of social development.

Fine particulate matter disrupts bile acid homeostasis in hepatocytes via binding to and activating farnesoid X receptor

Fine particulate matter (PM2.5)-induced metabolic disorders have attracted increasing attention, however, the underlying molecular mechanism of PM2.5-induced hepatic bile acid disorder remains unclear. In this study, we investigated the effects of PM2.5 components on the disruption of bile acid in hepatocytes through farnesoid X receptor (FXR) pathway. The receptor binding assays showed that PM2.5 extracts bound to FXR directly, with half inhibitory concentration (IC50) value of 21.7 μg/mL. PM2.5 extracts significantly promoted FXR-mediated transcriptional activity at 12.5 μg/mL. In mouse primary hepatocytes, we found PM2.5 extracts (100 μg/mL) significantly decreased the total bile acid levels, inhibited the expression of bile acid synthesis gene (Cholesterol 7 alpha-hydroxylase, Cyp7a1), and increased the expression of bile acid transport genes (Multidrug resistance associated protein 2, Abcc2; and Bile salt export pump, Abcb11). Moreover, these alterations were significantly attenuated by knocking down FXR in hepatocytes. We further divided the organic components and water-soluble components from PM2.5, and found that two components bound to and activated FXR, and decreased the bile acid levels in hepatocytes. In addition, benzo[a]pyrene (B[a]P) and cadmium (Cd) were identified as two bioactive components in PM2.5-induced bile acid disorders through FXR signaling pathway. Overall, we found PM2.5 components could bind to and activate FXR, thereby disrupting bile acid synthesis and transport in hepatocytes. These new findings also provide new insights into PM2.5-induced toxicity through nuclear receptor pathways.

Global variability in atmospheric new particle formation mechanisms

A key challenge in aerosol pollution studies and climate change assessment is to understand how atmospheric aerosol particles are initially formed1,2. Although new particle formation (NPF) mechanisms have been described at specific sites3-6, in most regions, such mechanisms remain uncertain to a large extent because of the limited ability of atmospheric models to simulate critical NPF processes1,7. Here we synthesize molecular-level experiments to develop comprehensive representations of 11 NPF mechanisms and the complex chemical transformation of precursor gases in a fully coupled global climate model. Combined simulations and observations show that the dominant NPF mechanisms are distinct worldwide and vary with region and altitude. Previously neglected or underrepresented mechanisms involving organics, amines, iodine oxoacids and HNO3 probably dominate NPF in most regions with high concentrations of aerosols or large aerosol radiative forcing; such regions include oceanic and human-polluted continental boundary layers, as well as the upper troposphere over rainforests and Asian monsoon regions. These underrepresented mechanisms also play notable roles in other areas, such as the upper troposphere of the Pacific and Atlantic oceans. Accordingly, NPF accounts for different fractions (10-80%) of the nuclei on which cloud forms at 0.5% supersaturation over various regions in the lower troposphere. The comprehensive simulation of global NPF mechanisms can help improve estimation and source attribution of the climate effects of aerosols.

Unequal Health Risks and Attributable Mortality Burden of Source-Specific PM2.5 in China

Anthropogenic emissions, originating from human activities, stand as the primary contributors to PM2.5, which is recognized as a global health threat. The disease burden associated with PM2.5 has been extensively documented. However, the prevailing estimations have predominantly relied on PM2.5 exposure-response functions, neglecting the distinct risks posed by PM2.5 from various sources. China has experienced a significant reduction in the PM2.5 concentration due to stringent emission controls. With diverse sources and abundant mortality data, this situation provides a unique opportunity to estimate short-term source-specific attributable mortality. Our approach involves an integrated unequal health risk-oriented modeling in China, incorporating a source-oriented Community Multiscale Air Quality model, an adjustment and downscaling method for exposure measurement, a generalized linear model with random-effects meta-analysis, and premature mortality estimation. Adhering to the unequal health risk concept, we calculated the attributable mortality of multiple PM2.5 sources by determining the source risk-adjusted factor. In this study, we observed varying excess risks associated with multiple PM2.5 sources, with transportation-related PM2.5 exhibiting the most substantial association. An interquartile range increase (7.65 μg/m3) was linked to a 1.98% higher daily nonaccidental mortality. Residential use- and transportation-related PM2.5 emerged as the two principal sources of premature mortality. In 2018, a remarkable 53,381 avoiding deaths were estimated compared to 2013, and over 67% of these were attributed to reductions in coal-dependent sources. Notably, transportation-related PM2.5 emerged as the largest contributor to premature mortality in 2018. This study underscores the significance of a new source-oriented health risk assessment to support actions aimed at reducing air pollution. It strongly advocates for heightened attention to PM2.5 reductions in the transportation sector in China.

Spatially and Temporally Differentiated NOx and VOCs Emission Abatement Could Effectively Gain O3-Related Health Benefits

The increasing level of O3 pollution in China significantly exacerbates the long-term O3 health damage, and an optimized health-oriented strategy for NOx and VOCs emission abatement is needed. Here, we developed an integrated evaluation and optimization system for the O3 control strategy by merging a response surface model for the O3-related mortality and an optimization module. Applying this system to the Yangtze River Delta (YRD), we evaluated driving factors for mortality changes from 2013 to 2017, quantified spatial and temporal O3-related mortality responses to precursor emission abatement, and optimized a health-oriented control strategy. Results indicate that insufficient NOx emission abatement combined with deficient VOCs control from 2013 to 2017 aggravated O3-related mortality, particularly during spring and autumn. Northern YRD should promote VOCs control due to higher VOC-limited characteristics, whereas fastening NOx emission abatement is more favorable in southern YRD. Moreover, promotion of NOx mitigation in late spring and summer and facilitating VOCs control in spring and autumn could further reduce O3-related mortality by nearly 10% compared to the control strategy without seasonal differences. These findings highlight that a spatially and temporally differentiated NOx and VOCs emission control strategy could gain more O3-related health benefits, offering valuable insights to regions with severe ozone pollution all over the world.

The Long Hazy Tail: Analysis of the Impacts and Trends of Severe Outdoor and Indoor Air Pollution in North China

China, especially the densely populated North China region, experienced severe haze events in the past decade that concerned the public. Although the most extreme cases have been largely eliminated through recent mitigation measures, severe outdoor air pollution persists and its environmental impact needs to be understood. Severe indoor pollution draws less public attention due to the short visible distance indoors, but its public health impacts cannot be ignored. Herein, we assess the trends and impacts of severe outdoor and indoor air pollution in North China from 2014 to 2021. Our results demonstrate the uneven contribution of severe hazy days to ambient and exposure concentrations of particulate matter with an aerodynamic diameter <2.5 (PM2.5). Although severe indoor pollution contributes to indoor PM2.5 concentrations (23%) to a similar extent as severe haze contributes to ambient PM2.5 concentrations (21%), the former's contribution to premature deaths was significantly higher. Furthermore, residential emissions contributed more in the higher PM2.5 concentration range both indoors and outdoors. Notably, severe haze had greater health impacts on urban residents, while severe indoor pollution was more impactful in rural areas. Our findings suggest that, besides reducing severe haze, mitigating severe indoor pollution is an important aspect of combating air pollution, especially toward improving public health.

Accountability analysis of health benefits related to National Action Plan on Air Pollution Prevention and Control in China

China is one of the largest producers and consumers of coal in the world. The National Action Plan on Air Pollution Prevention and Control in China (2013-2017) particularly aimed to reduce emissions from coal combustion. Here, we show whether the acute health effects of PM2.5 changed from 2013 to 2018 and factors that might account for any observed changes in the Beijing-Tianjin-Hebei (BTH) and the surrounding areas where there were major reductions in PM2.5 concentrations. We used a two-stage analysis strategy, with a quasi-Poisson regression model and a random effects meta-analysis, to assess the effects of PM2.5 on mortality in the 47 counties of BTH. We found that the mean daily PM2.5 levels and the SO42- component ratio dramatically decreased in the study period, which was likely related to the control of coal emissions. Subsequently, the acute effects of PM2.5 were significantly decreased for total and circulatory mortality. A 10 μg/m3 increase in PM2.5 concentrations was associated with a 0.16% (95% CI: 0.08, 0.24%) and 0.02% (95% CI: -0.09, 0.13%) increase in mortality from 2013 to 2015 and from 2016 to 2018, respectively. The changes in air pollution sources or PM2.5 components appeared to have played a core role in reducing the health effects. The air pollution control measures implemented recently targeting coal emissions taken in China may have resulted in significant health benefits.

Policy implications for synergistic management of PM2.5 and O3 pollution from a pattern-process-sustainability perspective in China

In recent years, the pattern of air pollution in China has changed profoundly, and PM2.5 and surface ozone (O3) have become the main air pollutants affecting the air quality of cities and regions in China. The synergistic control of the two has become the key to the sustainable improvement of air quality in China. In this study, we investigated and analyzed the spatial and temporal distribution patterns, exposure health risks, key drivers, and sustainable characteristics of PM2.5 and O3 concentrations in China from 2013 to 2022 at the national and city cluster scales by combining methodological models such as spatial statistics, trend analysis, exposure-response function, Hurst index, and multi-scale geographically weighted regression (MGWR) model. Ultimately, a synergistic management system for PM2.5 and O3 pollution was proposed. The results showed that: (1) The PM2.5 concentration decreased at a rate of 1.45 μg/m3 per year (p < 0.05), while the O3 concentration increased at a rate of 2.54 μg/m3 per year (p < 0.05). The trends of the two concentrations showed significant differences in spatial distribution. (2) Population exposure risks to pollutants showed an increasing trend, with PM2.5 and O3 increasing by 55.1 % and 42.7 %, respectively. The annual deaths associated with exposure to PM2.5 and O3 demonstrated a decreasing and inverted U-shaped trend, respectively, with annual average deaths of 1.312 million and 98,000. Significant regional disparities in health risks from these pollutants were influenced by socio-economic factors such as industrial activities and population density. In the future, it is expected that more than half of China's regions will be exposed to rising risks of PM2.5 and O3 population exposure. (3) Key drivers of regional exacerbation in PM2.5 and O3 levels include the number of industrial enterprises above designated size (NSIE) and population agglomeration (PA), while the disposable income of urban residents (URDI), technological innovation (TI), and government attention level (GAL) emerged as primary factors in controlling pollution hotspots, ranked in order of influence from greatest to least as TI > GAL > URDI. Overall, this study sheds light on the current status of air pollution and health risk sustainability in China and enhances the understanding of future air pollution dynamics in China. The results of the study may help to develop effective targeted control measures to synergize the management of PM2.5 and O3 in different regions.

Multi-objective optimisation model of a low-cost path to peaking carbon dioxide emissions and carbon neutrality in China

A low-cost path system for achieving carbon neutrality in China was modelled using multi-objective programming by integrating industrial production, electric power, heating, transportation, and forest carbon sequestration. We aimed to minimise the total system cost, CO2 emissions, and air pollutants. The constraints included China's targets of peaking CO2 emissions before 2030; achieving carbon neutrality before 2060; ensuring industry, power, heating, and transportation supplies; promoting green energy; and implementing emission control. The model accounted for industries with high coal consumption, such as steel and chemical industries. Various power sources were considered, including coal-fired, nuclear, wind, and solar energy. Forest carbon sink and carbon capture and storage technologies were employed to achieve the emission reduction goals. The model, which was validated using available research data, offered cost-effective path schemes and exhibited high validity. Our findings emphasise the importance of structural adjustments and emission control, with electric power, heating, and transportation sectors showing higher feasibility and providing greater contributions to achieving carbon neutrality than other industries. Conversely, industrial transformation in sectors such as iron and steel, chemical, and construction materials had low feasibility and limited contribution. The modelling outcomes provide valuable insights for developing low-cost, carbon emission-targeted transportation structures in China's complex system. The results presented here demonstrate the global applicability of this method in contributing to plans aimed at meeting key carbon reduction targets.

Unpacking the factors contributing to changes in PM2.5-associated mortality in China from 2013 to 2019

From 2013 to 2019, a series of air pollution control actions significantly reduced PM2.5 pollution in China. Control actions included changes in activity levels, structural adjustment (SA) policy, energy and material saving (EMS) policy, and end-of-pipe (EOP) control in several sources, which have not been systematically studied in previous studies. Here, we integrate an emission inventory, a chemical transport model, a health impact assessment model, and a scenario analysis to quantify the contribution of each control action across a range of major emission sources to the changes in PM2.5 concentrations and associated mortality in China from 2013 to 2019. Assuming equal toxicity of PM2.5 from all the sources, we estimate that PM2.5-related mortality decreased from 2.52 (95 % confidence interval, 2.13-2.88) to 1.94 (1.62-2.24) million deaths. Anthropogenic emission reductions and declining baseline incidence rates significantly contributed to health benefits, but population aging partially offset their impact. Among the major sources, controls on power plants and industrial boilers were responsible for the highest reduction in PM2.5-related mortality (∼80 %), followed by industrial processes (∼40 %), residential combustion (∼40 %), and transportation (∼30 %). However, considering the potentially higher relative risks of power plant PM2.5, the adverse effects avoided by their control could be ∼2.4 times the current estimation. Our power plant sensitivity analyses indicate that future estimates of source-specific PM2.5 health effects should incorporate variations in individual source PM2.5 effect coefficients when available. As for the control actions, while activity levels increased for most sources, SA policy significantly reduced the emissions in residential combustion and industrial boilers, and EOP control dominated the contribution in health benefits in most sources except residential combustion. Considering the emission reduction potential by source and control actions in 2019, our results suggest that promoting clean energy in residential combustion and enforcing more stringent EOP control in the iron and steel industry should be prioritized in the future.

Decoding the effect of demographic factors on environmental health based on city-level PM2.5 pollution in China

Although considerable health effects are gained from air quality improvement action plans implemented in China recently, they may have been amplified or offset due to the complexity and uncertainty of the changing demographic factors. In this study, we developed a framework for analyzing the effects of demographic factors on environmental health effects, focusing on three aspects: population scale, age structure, and spatial distribution. We quantified the above three effects by investigating how the health endpoint changed by the three demographic factors, based on a strategy of counterfactual and step-by-step relaxing hypothesis. We found that the increasing population scale and population aging caused 44,279 to 292,442 premature deaths, which offset the health effect of air quality improvement efforts for China. The change in population spatial distribution, in general, has little impact on the health effects of air quality improvement. Furthermore, the three effects are distributed unevenly across regions, especially the spatial distribution effect. Considering the widespread effect of demographic factors, PM2.5 concentration should be further reduced, and the aged population and mega-cities should be targeted for managing air quality in a cost-effective manner.

Meteorological and anthropogenic drivers of surface ozone change in the North China Plain in 2015-2021

Surface ozone (O3) concentrations in China have increased largely in the past decade. An accurate understanding of O3 pollution evolution is critical for making effective regulatory policies. Here we integrate data- and process-based models to explore the drivers of the observed summertime surface O3 change in the North China Plain (NCP) over 2015-2021. The data-based model by the deep learning (DL) suggests the reverse of meteorological contributions to the observed O3 change, i.e., 0.14 ppb/y in 2015-2019 and -1.74 ppb/y in 2019-2021. This is mainly resulted from the reversed changes in meteorological variables in surface air temperature and relative humidity. The simulations from a global chemical transport model, GEOS-Chem, also support those results, i.e., the meteorological contribution to O3 changes are 0.26 ppb/y in 2015-2019 and -0.74 ppb/y in 2019-2021. Furthermore, our analysis exhibits possible weakened anthropogenic contributions to surface O3 rise, for example, 1.53 and 0.54 ppb/y by DL in 2015-2019 and 2019-2021, respectively. Similarly, GEOS-Chem simulations suggest an accelerated decrease in surface O3 concentrations driven by the decline in nitrogen dioxide (NO2) concentrations, i.e., approximately 0.4 and 1.2 ppb in 2015-2019 and 2019-2021, respectively. The combined effects of meteorological and anthropogenic contributions led to a significant decrease in surface O3 concentrations by -1.20 ppb/y in 2019-2021. The findings in this work offer valuable insights to mitigate O3 pollution in China.

Cost-benefits analysis of ultra-low emissions standard on air quality and health impact in thermal power plants in China

As China's largest energy infrastructure, thermal power plant consumed approximately half of China's coal over the past decade and threatened air quality, human health and socioeconomic development. Thus, a series of control policies have been implemented to alleviate those impacts in China. Particularly, China has witnessed unprecedented declines in air pollutant emissions from thermal power plants since the ultra-low emissions (ULE) standards were implemented. In contrast, the effect of the ULE policy on air quality, health and cost benefits remains poorly understood. Therefore, this study estimates the improved air quality and associated health and economic benefits under the ULE standards in the thermal power sector by using a measure-specific approach, combining a bottom-up emission inventory, an atmospheric model, a health assessment model and a cost analysis model. The results show that all the control measures lead to reduced air pollution, and renovating pre-existing units (RPU) is the most effective. Compared to without implementing the ULE policy, the population-weighted average PM2.5 and O3 concentrations decreased by 1.50 μg/m3 and 0.87 ppm, and 67,831 premature deaths could be avoided nationally. Furthermore, the results also show the net economic benefits of combining health benefits and costs due to control measures are 109.92 billion Yuan (in 2015 value) in China. The comprehensive results reveal that the health benefits outweigh the direct policy. Based on these empirical findings and the specific circumstances of China, we suggest that RPU should be further promoted to the entire of China, and if necessary, establish a long-term compensation mechanism for inter-provincial interests and institute and enforce comprehensive policies that carefully consider the health impacts of policies. This study provides strong arguments for China's policy-making and considering tightening emission standards for thermal power plants worldwide.

Estimation of health risk and economic loss attributable to PM2.5 and O3 pollution in Jilin Province, China

Ambient pollutants, particularly fine particulate matter (PM2.5) and ozone (O3), pose significant risks to both public health and economic development. In recent years, PM2.5 concentration in China has decreased significantly, whereas that of O3 has increased rapidly, leading to considerable health risks. In this study, a generalized additive model was employed to establish the relationship of PM2.5 and O3 exposure with non-accidental mortality across 17 districts and counties in Jilin Province, China, over 2015-2016. The health burden and economic losses attributable to PM2.5 and O3 were assessed using high-resolution satellite and population data. According to the results, per 10 µg/m3 increase in PM2.5 and O3 concentrations related to an overall relative risk (95% confidence interval) of 1.004 (1.001-1.007) and 1.009 (1.005-1.012), respectively. In general, the spatial distribution of mortality and economic losses was uneven. Throughout the study period, a total of 23,051.274 mortalities and 27,825.015 million Chinese Yuan (CNY) in economic losses were attributed to O3 exposure, which considerably surpassing the 5,450.716 mortalities and 6,553,780 million CNY in economic losses attributed to PM2.5 exposure. The O3-related health risks and economic losses increased by 3.75% and 9.3% from 2015 to 2016, while those linked to PM2.5 decreased by 23.33% and 18.7%. Sensitivity analysis results indicated that changes in pollutant concentrations were the major factors affecting mortality rather than baseline mortality and population.

Achieving health-oriented air pollution control requires integrating unequal toxicities of industrial particles

Protecting human health from fine particulate matter (PM) pollution is the ambitious goal of clean air actions, but current control strategies  largely ignore the role of source-specific PM toxicity. Here, we proposed health-oriented control strategies by integrating the unequal toxic potencies of the most polluting industrial PMs. Iron and steel industry (ISI)-emitted PM2.5 exhibit about one order of magnitude higher toxic potency than those of cement and power industries. Compared with the current mass-based control strategy (prioritizing implementation of ultralow emission standards in the power sector), the proposed health-oriented control strategy (priority control of the ISI sector) could generate 5.4 times higher reduction in population-weighted toxic potency-adjusted PM2.5 exposure among polluting industries in China. Furthermore, the marginal abatement cost per unit of toxic potency-adjusted mass of ISI-emitted PM2.5 is only a quarter of that of the other two sectors under ultralow emission scenarios. We highlight that a health-oriented air pollution control strategy is urgently required to achieve cost-effective reductions in particulate exposure risks.

Synergetic roadmap of carbon neutrality and clean air for China

It is well recognized that carbon dioxide and air pollutants share similar emission sources so that synergetic policies on climate change mitigation and air pollution control can lead to remarkable co-benefits on greenhouse gas reduction, air quality improvement, and improved health. In the context of carbon peak, carbon neutrality, and clean air policies, this perspective tracks and analyzes the process of the synergetic governance of air pollution and climate change in China by developing and monitoring 18 indicators. The 18 indicators cover the following five aspects: air pollution and associated weather-climate conditions, progress in structural transition, sources, inks, and mitigation pathway of atmospheric composition, health impacts and benefits of coordinated control, and synergetic governance system and practices. By tracking the progress in each indicator, this perspective presents the major accomplishment of coordinated control, identifies the emerging challenges toward the synergetic governance, and provides policy recommendations for designing a synergetic roadmap of Carbon Neutrality and Clean Air for China.

Health burden evaluation of industrial parks caused by PM2.5 pollution at city scale

Industrial park is an important emission sector of PM2.5 pollution. Previous studies have provided valuable information on the impact of PM2.5 from industrial parks on human health, but relevant studies at city scale are limited. In this study, the health burden of industrial parks was evaluated based on PM2.5-related premature deaths and economic contributions. The premature deaths were calculated in terms of a novel research model by integrating the Bayesian maximum entropy (BME) model, weighted concentration-weighted trajectory (WCWT), and integrated exposure-response function (IER). Take Tianjin City for example, it was found that since the main diffusion direction of PM2.5 in Tianjin is from south to north, the industrial parks in the south of Tianjin and close to the central city with high population density have high health burden. These industrial parks need to be focused on or even relocated in the future. The research model can provide scientific basis for the health burden evaluation of industrial parks at city scale, so as to help local governments optimize the layout of industrial parks and formulate environmental responsibility management policies for industrial parks.

Mismatched Social Welfare Allocation and PM2.5-Related Health Damage along Value Chains within China

Value chains have played a critical part in the growth. However, the fairness of the social welfare allocation along the value chain is largely underinvestigated, especially when considering the harmful environmental and health effects associated with the production processes. We used fine-scale profiling to analyze the social welfare allocation along China's domestic value chain within the context of environmental and health effects and investigated the underlying mechanisms. Our results suggested that the top 10% regions in the value chain obtained 2.9 times more social income and 2.1 times more job opportunities than the average, with much lower health damage. Further inspection showed a significant contribution of the "siphon effect"─major resource providers suffer the most in terms of localized health damage along with insufficient social welfare for compensation. We found that inter-region atmosphere transport results in redistribution for 53% health damages, which decreases the welfare-damage mismatch at "suffering" regions but also causes serious health damage to more than half of regions and populations in total. Specifically, around 10% of regions have lower social welfare and also experienced a significant increase in health damage caused by atmospheric transport. These results highlighted the necessity of a value chain-oriented, quantitative compensation-driven policy.

Economic Growth Facilitates Household Fuel Use Transition to Reduce PM2.5-Related Deaths in China

Exposure to ambient and indoor particle matter (PM2.5) leads to millions of premature deaths in China. In recent years, indoor air pollution and premature deaths associated with polluting fuel cooking demonstrate an abrupt decline. However, the driving forces behind the mortality change are still unclear due to the uncertainty in household fuel use prediction. Here, we propose an integrated approach to estimate the fuel use fractions and PM2.5-related deaths from outdoor and indoor sources during 2000-2020 across China. Our model estimated 1.67 and 1.21 million premature deaths attributable to PM2.5 exposure in 2000 and 2020, respectively. We find that the residential energy transition is associated with a substantial reduction in premature deaths from indoor sources, with 100,000 (95% CI: 76,000-122,000) for urban and 265,000 (228,000-300,000) for rural populations during 2000-2020. Economic growth is the dominant driver of fuel use transition and avoids 21% related deaths (357,000, 315,000-402,000) from polluting fuel cooking since 2000, which offsets the adverse impact of ambient emissions contributed by economic growth. Our findings give an insight into the coupled impact of socioeconomic factors in reshaping health burden in exposure pathways.

Change of Composition, Source Contribution, and Oxidative Effects of Environmental PM2.5 in the Respiratory Tract

Fine particulate matter is a leading air pollutant, and its composition profile relates to sources and health effects. The human respiratory tract hosts a warmer and more humid microenvironment in contrast with peripheral environments. However, how the human respiratory tract impacts the transformation of the composition of environmental PM2.5 once they are inhaled and consequently changes of source contribution and health effects are unknown. Here, we show that the respiratory tract can make these properties of PM2.5 reaching the lung different from environmental PM2.5. We found via an in vitro model that the warm and humid conditions drive the desorption of nitrate (about 60%) and ammonium (about 31%) out of PM2.5 during the inhalation process and consequently make source contribution profiles for respiratory tract-deposited PM2.5 different from that for environmental PM2.5 as suggested in 11 Chinese cities and 12 US cities. We also observed that oxidative potential, one of the main health risk causes of PM2.5, increases by 41% after PM2.5 travels through the respiratory tract model. Our results reveal that PM2.5 inhaled in the lung differs from environmental PM2.5. This work provides a starting point for more health-oriented source apportionment, physiology-based health evaluation, and cost-effective control of PM2.5 pollution.

Regional joint PM2.5-O3 control policy benefits further air quality improvement and human health protection in Beijing-Tianjin-Hebei and its surrounding areas

Beijing-Tianjin-Hebei and its surrounding areas (hereinafter referred to as "2+26" cities) are one of the most severe air pollution areas in China. The fine particulate matter (PM_2.5) and surface ozone (O₃) pollution have aroused a significant concern on the national scale. In this study, we analyzed the pollution characteristics of PM_2.5 and O₃ in "2+26" cities, and then estimated the health burden and economic loss before and after the implementation of the joint PM_2.5-O₃ control policy. During 2017-2019, PM_2.5 concentration reduced by 19% while the maximum daily 8 hr average (MDA8) O₃ stayed stable in "2+26" cities. Spatially, PM_2.5 pollution in the south-central area and O₃ pollution in the central region were more severe than anywhere else. With the reduction in PM_2.5 concentration, premature deaths from PM_2.5 decreased by 18% from 2017 to 2019. In contrast, premature deaths from O₃ increased by 5%. Noticeably, the huge potential health benefits can be gained after the implementation of a joint PM_2.5-O₃ control policy. The premature deaths attributed to PM_2.5 and O₃ would be reduced by 91.6% and 89.1%, and the avoidable economic loss would be 60.8 billion Chinese Yuan (CNY), and 68.4 billion CNY in 2035 compared with that in 2019, respectively. Therefore, it is of significance to implement the joint PM_2.5-O₃ control policy for improving public health and economic development.

Chronic and acute health effects of PM2.5 exposure and the basis of pollution control targets

Ho Chi Minh City (HCMC) is changing and expanding quickly, leading to environmental consequences that seriously threaten human health. PM2.5 pollution is one of the main causes of premature death. In this context, studies have evaluated strategies to control and reduce air pollution; such pollution-control measures need to be economically justified. The objective of this study was to assess the socio-economic damage caused by exposure to the current pollution scenario, taking 2019 as the base year. A methodology for calculating and evaluating the economic and environmental benefits of air pollution reduction was implemented. This study aimed to simultaneously evaluate the impacts of both short-term (acute) and long-term (chronic) PM2.5 pollution exposure on human health, providing a comprehensive overview of economic losses attributable to such pollution. Spatial partitioning (inner-city and suburban) on health risks of PM2.5 and detailed construction of health impact maps by age group and sex on a spatial resolution grid (3.0 km × 3.0 km) was performed. The calculation results show that the economic loss from premature deaths due to short-term exposure (approximately 38.86 trillion VND) is higher than that from long-term exposure (approximately 14.89 trillion VND). As the government of HCMC has been developing control and mitigation solutions for the Air Quality Action Plan towards short- and medium-term goals in 2030, focusing mainly on PM2.5, the results of this study will help policymakers develop a roadmap to reduce the impact of PM2.5 during 2025-2030.

A multifaceted approach to explain short- and long-term PM2.5 concentration changes in Northeast Asia in the month of January during 2016-2021

Changes in PM_2.5 concentrations are influenced by interwoven impacts of key drivers (e.g., meteorology, local emissions, and regional emissions). However, it is challenging to quantitatively disentangle their impacts individually at once. Therefore, we introduced a multifaceted approach (i.e., meteorology vs. emissions and self-contribution vs. long-range transport) to analyze the effects of major drivers for long- and short-term PM_2.5 concentration changes based on observation and simulation in the month of January during 2016-2021 in Northeast Asia. For the simulations, we conducted modeling with the WRF-CMAQ system. The observed PM_2.5 concentrations in China and South Korea in January 2021 decreased by 13.7 and 9.8 μg/m³, respectively, compared to those in January 2016. Emission change was the dominant factor to reduce PM_2.5 concentrations in China (-115%) and South Korea (-74%) for the 6 years. However, the short-term changes in PM_2.5 concentrations between January of 2020-2021 were mainly driven by meteorological conditions in China (-73%) and South Korea (-68%). At the same time, in South Korea located in downwind area, the impact of long-range transport from upwind area (LTI) decreased by 55% (9.6 μg/m³) over the 6 years whereas the impact of local emissions increased (+2.9 μg/m³/year) during 2016-2019 but decreased (-4.5 μg/m³/year) during 2019-2021. Additionally, PM_2.5 concentrations in the upwind area showed a positive relationship with LTIs. However, for the days when westerly winds became weak in the downwind area, high PM_2.5 concentrations in upwind area did not lead to high LTIs. These results imply that the decline of PM_2.5 concentrations in South Korea was significantly affected by a combination of emission reduction in upwind area and meteorological conditions that hinder long-range transport. The proposed multifaceted approach can identify the main drivers of PM_2.5 concentration change in a region by considering the regional characteristics.

Assessing the health impacts of PM2.5 and ozone pollution and their comprehensive correlation in Chinese cities based on extended correlation coefficient

The coordinated control of PM_2.5 and ozone pollution is becoming more and more important in the current and next stage of Chinese environmental pollution control. Existing studies are unable to provide sufficient quantitative assessments of the correlation of PM_2.5 and ozone pollution to support the coordinated control of the two air pollutants. This study develops a systematic method to comprehensively assess the correlation between PM_2.5 and ozone pollution, including the evaluation of the impact of two air pollutants on human health and the extended correlation coefficient (ECC) for assessing the bivariate correlation index of PM_2.5-ozone pollution in Chinese cities. According to the latest studies on epidemiology conducted in China, we take cardiovascular and cerebrovascular diseases and respiratory diseases as the ozone pollution's health burden when evaluating the health impact of ozone pollution. The results show that the health impact of PM_2.5 in China decreases by 25.9 % from 2015 to 2021, while the health impact of ozone increases by 11.8 %. The ECC of 335 cities in China shows an increasing-decreasing trend but has generally increased from 2015 to 2021. The study provides important support for an in-depth understanding of the correlation and development trend of Chinese PM_2.5 and ozone pollution by classifying the comprehensive PM_2.5-ozone correlation performances of Chinese cities into four types. China or other countries will get better environmental benefits by implementing different coordinated management approaches for different correlative types of regions based on the assessment method in this study.

Tracing the sources of PM2.5-related health burden in China

Fine particulate matter (PM2.5) poses a major environmental risk to human health. We estimated PM2.5-related premature deaths in 30 Chinese provinces in 2020 using an integrated exposure response model based on monitored concentrations and obtained regional and sectoral contributions based on the atmospheric transport of the atmospheric transport contribution matrix. From the perspective of regional- and sectoral-scale effects, the results revealed that 740,140 [95% confidence interval (CI):646,538-839,968] premature deaths were related to PM2.5 in 2020, mainly in East (30%), Central (18%), and North (15%) China. Manufacturing activity was found to be the major cause of PM2.5-related premature deaths, accounting for over 50% of the deaths. From the perspective of the interregional atmospheric transport effect, although local emissions were the major source of PM2.5-related premature deaths in all regions, non-local emissions contributed approximately 30%. The overall trend in the net atmospheric transport direction was from north to south. In particular, the Guangdong, Guangxi, and Hainan provinces of South China received contributions of more than 40% from non-local provinces, mainly from the East and Central China. Combined with economic data, the regions and sectors with the highest PM2.5-related premature deaths per unit output or consumption include the manufacturing and household sectors in North and Northeast China and transportation, agriculture, and electricity in Central China. Therefore, from the perspective of the above three impacts, although the potential impact of PM2.5 pollution on health in China has decreased with the decrease in PM2.5 concentration in the past decade owing to strict air pollution control, the central and northern parts of China are still the key areas requiring air pollution control. The health impacts of air pollution associated with the rapid development of China's manufacturing industry in the post-pandemic era cannot be ignored.

The pollution control effect of the atmospheric environmental policy in autumn and winter: Evidence from the daily data of Chinese cities

The pollution control effect of seasonal environmental regulation policies in developing countries still lacks empirical evidence. In 2017, China implemented its first Atmospheric Environmental Policy in Autumn and Winter (AEPAW) to coordinate efforts among cities in reducing air pollutant emissions. Taking the daily panel data of 174 cities in northern China from July 2017 to July 2020 as samples, this paper empirically examines the pollution control effect of the AEPAW using a difference-in-differences model, a difference-in-difference-in-differences model, and a regression discontinuity design. The results show that the AEPAW significantly improves air quality in autumn and winter, with the air quality index decreasing by 5.6% on average by reducing PM_2.5, PM₁₀, SO₂, and O₃ emissions. However, the AEPAW only creates a short-term "policy-induced blue sky", and there exists a phenomenon of "retaliatory pollution" after the AEPAW ends. Besides, the pollution control effect of the AEPAW is moderated by the heterogeneity of the national "Two Sessions" and the Central Environmental Protection Inspection. The implementation of the AEPAW also has a significant spillover effect on air pollution control in surrounding areas. The net benefit from the AEPAW is estimated to be approximately US$ 670 million per year. These findings not only have practical significance for strengthening the comprehensive control of air pollution in China, but also give some important references for other developing countries.

Substantial short- and long-term health effect due to PM2.5 and the constituents even under future emission reductions in China

Heavy pollution events of fine particulate matter (PM_2.5) frequently occur in China, seriously affecting the human health. However, how meteorological factors and anthropogenic emissions affect PM_2.5 and the major constituents, as well as the subsequent health effect, remains unclear. Here, based on regional climate and air quality models Weather Research and Forecasting (WRF) and Community Multiscale Air Quality (CMAQ), the PM_2.5 and major constituents in China at present and mid-century under the carbon neutral scenario Shared Socioeconomic Pathways (SSP)1-2.6 are simulated. Due to anthropogenic emission reduction, concentrations of PM_2.5 and the constituents decrease substantially in SSP1-2.6. The long-term exposure premature deaths at present are 2.23 million per year in mainland China, which is projected to increase by 76 % under SSP1-2.6 despite emission reduction, primarily attributable to aging which strikingly offsets the effect of air quality improvement. The number of annual premature deaths resulting from short-term exposure is 228,104 in mainland China at present, which is projected to decrease in the future. Using North China Plain as an example, we identify that among the major constituents of PM_2.5, organic carbon leads to the most short-term exposure deaths considering the largest exposure-response coefficient. Regarding the abnormally meteorological conditions, we find, relative to low relative humidity (RH) and non-stagnation, the compound events, defined as concurrence of high RH and atmospheric stagnation, exhibit an amplified role inducing larger premature deaths compared to the additive effect of the individual event of high RH and atmospheric stagnation. This nonlinear effect occurs at both present and future, but diminished in future due to emission reductions. Our study highlights the importance of considering both the long- and short-term premature deaths associated with PM_2.5 and the constituents, as well as the critical effect of extreme weather events.

Atmospheric dry deposition fluxes of trace metals over the Eastern China Marginal Seas: Impact of emission controls

Atmospheric deposition is an important exogenous input of trace metals to Eastern China Marginal Seas (ECMS), which is strongly affected by human activities. With emission control practices implemented in China, it still remains unknown what changes have taken place in the atmospheric dry depositions of the trace metals over ECMS. This study aimed to estimate the atmospheric dry depositions of Zn, Pb, Cu, and Cd over ECMS via Weather Research and Forecasting Model-Community Multiscale Air Quality Modeling System (WRF-CMAQ) in the two winter periods of January 2012 and January 2019 as well as to explore the impacts of emission control on the depositions. The anthropogenic metal emissions from China, the Korean Peninsula, Japan, and marine ships were investigated in this study. In 2012, the dry deposition fluxes of Zn, Pb, Cu, and Cd over ECMS were in the ranges of 0.50-3.4 μg m^-2 d^-1, 0.22-1.9 μg m^-2 d^-1, 0.14-0.90 μg m^-2 d^-1, and 12-88 ng m^-2 d^-1, respectively. The deposition fluxes of the four metals over Bohai Sea (BS) and Yellow Sea (YS) were 2-3 times those over East China Sea (ECS). Outflow of polluted air masses from East Asia increased the metal depositions by 3- 5-fold relative to clear days. Compared with 2012, a 5-85 % reduction in the metal depositions over ECMS were estimated in 2019, largest reductions were found over YS and BS. Meteorological variation was able to decrease or increase the metal depositions. However, the emission control only caused a reduction in the entire study region. The metal inputs to the sea were significantly lower from the ship emissions than from the continental anthropogenic emissions, although the proportion of the ship emissions in the total metal depositions rose slightly from 2012 to 2019.

Trends of source apportioned PM2.5 in Tianjin over 2013-2019: Impacts of Clean Air Actions

A long-term (2013-2019) PM_2.5 speciation dataset measured in Tianjin, the largest industrial city in northern China, was analyzed with dispersion normalized positive matrix factorization (DN-PMF). The trends of source apportioned PM_2.5 were used to assess the effectiveness of source-specific control policies and measures in support of the two China's Clean Air Actions implemented nationwide in 2013-2017 and 2018-2020, respectively. Eight sources were resolved from the DN-PMF analysis: coal combustion (CC), biomass burning (BB), vehicular emissions, dust, steelmaking and galvanizing emissions, a mixed sulfate-rich factor and secondary nitrate. After adjustment for meteorological fluctuations, a substantial improvement in PM_2.5 air quality was observed in Tianjin with decreases in PM_2.5 at an annual rate of 6.6%/y. PM_2.5 from CC decreased by 4.1%/y. The reductions in SO₂ concentration, PM_2.5 contributed by CC, and sulfate demonstrated the improved control of CC-related emissions and fuel quality. Policies aimed at eliminating winter-heating pollution have had substantial success as shown by reduced heating-related SO₂, CC, and sulfate from 2013 to 2019. The two industrial source types showed sharp drops after the 2013 mandated controls went into effect to phaseout outdated iron/steel production and enforce tighter emission standards for these industries. BB reduced significantly by 2016 and remained low due to the no open field burning policy. Vehicular emissions and road/soil dust declined over the Action's first phase followed by positive upward trends, showing that further emission controls are needed. Nitrate concentrations remained constant although NO_X emissions dropped significantly. The lack of a decrease in nitrate may result from increased ammonia emissions from enhanced vehicular NO_X controls. The port and shipping emissions were evident implying their impacts on coastal air quality. These results affirm the effectiveness of the Clean Air Actions in reducing primary anthropogenic emissions. However, further emission reductions are needed to meet global health-based air quality standards.

Carbon Mitigation and Environmental Co-Benefits of a Clean Energy Transition in China's Industrial Parks

Industrial parks are emerging priorities for carbon mitigation. Here we analyze air quality, human health, and freshwater conservation co-benefits of decarbonizing the energy supply of 850 China's industrial parks. We examine a clean energy transition including early retirement of coal-fired facilities and subsequent replacement with grid electricity and onsite energy alternatives (municipal solid waste-to-energy, rooftop photovoltaic, and distributed wind power). We find that such a transition would reduce greenhouse gas emissions by 41% (equal to 7% of 2014 national CO2 equivalent emissions); emissions of SO2 by 41%, NOx by 32%, and PM2.5 by 43% and freshwater consumption by 20%, relative to a 2030 baseline scenario. Based on modeled air pollutant concentrations, we estimate such a clean energy transition will result in ∼42,000 avoided premature deaths annually due to reduced ambient PM2.5 and ozone exposure. Costs and benefits are monetized including technical costs of changes in equipment and energy use and societal benefits resulting from improvements in human health and reductions of climate impacts. We find that decarbonizing industrial parks brings annual economic benefits of US$30-156 billion in 2030. A clean energy transition in China's industrial parks thus provides both environmental and economic benefits.

Sources of Organic Aerosol in China from 2005 to 2019: A Modeling Analysis

Organic aerosol (OA) is a key component of fine particulate matter (PM_2.5) and affects the human health and leads to climate change. With strict control measures for air pollutants during the last decade, the OA concentration in China declined slowly, while its sources remain unclear. In this study, we simulate the primary OA (POA) and secondary OA (SOA) concentrations from 2005 to 2019 with a state-of-the-art air quality model, Community Multiscale Air Quality (CMAQ, version 5.3.2) coupled with a Two-Dimensional Volatility Basis Set (2D-VBS) module, and a long-term emission inventory of full-volatility organic compounds in China and conduct source apportionment and sensitivity analysis. The simulation results show that, from 2005 to 2019, the OA concentration in China decreased from 24.0 to 12.8 μg/m³ with most of the reduction from POA. The OA pollution from residential biomass burning declined 75% from 2005 to 2019, while it is still the major OA source in China. OA pollution from VCP increased by more than 2-fold and became the largest SOA source in China. From 2014 to 2019, the NO_x control in China slightly offset the decrease of SOA concentration due to elevated oxidation capacity.

Source Contributions to PM2.5-Related Mortality and Costs: Evidence for Emission Allocation and Compensation Strategies in China

The emissions from various pollution sources were not proportional to their contributions to ambient PM_2.5 concentrations and associated health burdens. That means even with the same total abatement targets, different abatement allocation strategies across emission sources can have distinct health benefits. Insufficient knowledge of various sources' contributions to health burdens in China, the country suffering substantial PM_2.5-related deaths, hindered the government from seeking optimized abatement allocation strategies. In this context, we separated the contributions of 155 emission sources (31 provinces × 5 sectors) to PM_2.5-related mortality across China in 2017 by coupling the Comprehensive Air Quality Model with Extensions (CAMx), Weather Research and Forecasting model (WRF), and health impact assessment model. We further identified the priority-control emission sources and quantified interprovincial ecological compensation volumes to alleviate inequality induced by emission allocation strategies. Results showed that PM_2.5 pollution caused 899,443 excess deaths and around 127 billion USD costs in 2017. Approximately half of the deaths and costs were attributable to emissions from sources outside the boundary of the regions where the deaths occurred. Twenty-five out of 155 emission sources that contributed to the top 60% mortality burdens and had high marginal abatement efficiencies in China shall be the priority-control emission sources. A 1 μg/m³ decrease of PM_2.5 concentration in regions where these key emission sources occur shall be compensated by 76-153 million USD in their receptor regions. Our study sheds light on the sources' contributions to mortality burdens and costs and provides scientific evidence for optimizing the emission allocation and compensation strategies in China. It also has wide implications for other countries suffering similar problems.

Extreme Emission Reduction Requirements for China to Achieve World Health Organization Global Air Quality Guidelines

A big gap exists between current air quality in China and the World Health Organization (WHO) global air quality guidelines (AQG) released in 2021. Previous studies on air pollution control have focused on emission reduction demand in China but ignored the influence of transboundary pollution, which has been proven to have a significant impact on air quality in China. Here, we develop an emission-concentration response surface model coupled with transboundary pollution to quantify the emission reduction demand for China to achieve WHO AQG. China cannot achieve WHO AQG by its own emission reduction for high transboundary pollution of both PM_2.5 and O₃. Reducing transboundary pollution will loosen the reduction demand for NH₃ and VOCs emissions in China. However, to meet 10 μg·m^-3 for PM_2.5 and 60 μg·m^-3 for peak season O₃, China still needs to reduce its emissions of SO₂, NO_x, NH₃, VOCs, and primary PM_2.5 by more than 95, 95, 76, 62, and 96% respectively, on the basis of 2015. We highlight that both extreme emission reduction in China and great efforts in addressing transboundary air pollution are crucial to reach WHO AQG.

Exploring Health Effects under Specific Causes of Mortality Based on 90 Definitions of PM2.5 and Cold Spell Combined Exposure in Shanghai, China

In this study, a total of 90 definitions were set up based on six air pollution definitions, five cold spell definitions, and three combined exposure scenarios. The relative risks (RRs) on all-cause, circulatory, and respiratory mortality were explored by a model combining a distributed linear lag model with quasi-Poisson regression. The definition in which daily PM_2.5 increases more than 75 μg/m³ for at least 2 days and the average temperature falls below the 10th percentile for at least 2 days produced the best model fit performance in all-cause mortality. The high peaks of the health effect were generally observed around the lag days 6-9. The cumulative relative risks (CRRs) were more significant in the simultaneous-exposure scenario and higher in respiratory mortality, where the highest CRR (12.15, 3.69-40.03) was observed in definition P1T5, in which daily PM_2.5 increases more than 75 μg/m³, and the average temperature falls below the 2.5th percentile for at least two days. For relative risk due to interaction (RERI), we found positive additive interactions (RERI > 0) between PM_2.5 pollution and cold spell, especially in respiratory mortality. Clarifying the definition of combined events can help policymakers to capture health risks and construct more effective risk warning systems.

An acid rain-friendly NH3 control strategy to maximize benefits toward human health and nitrogen deposition

Ammonia (NH₃) abatement remains controversial in China owing to its effectiveness in reducing PM_2.5 pollution and nitrogen deposition but with the potential risk of promoting acid rain formation, necessitating scientific guidance. Here, we propose a novel method for designing an NH₃ control strategy to mitigate both air pollution and nitrogen deposition without significantly exacerbating acid rain. This method involves extending the response surface model (RSM) to deposition using a delicately developed polynomial response function of deposition (i.e., dep-RSM). The Yangtze River Delta (YRD) dep-RSM application reveals that 16 out of 41 cities have NH₃ control potentials from 15 % to 71 %. Excellent NH₃ control potentials have been noted between April and June (78 %-92 %). From 2013 to 2017, the effective SO₂ and NO_x control significantly reduced wet sulfur and oxidized nitrogen deposition, providing considerable NH₃ abatement potentials (15 %-24 %) to further reduce PM_2.5 and nitrogen deposition by up to 2 % and 9 %, respectively, without acid rain exacerbation (the wet neutralization factor was maintained). Additionally, 57 % and 73 % NH₃ emission reduction potentials were obtained under acid rain constraints with 75 % and 86 % reductions in the other precursors to reduce the average PM_2.5 concentration below 25 and 15 μg/m³, and an additional 8408 and 14,459 premature deaths could only be avoided at an extra cost of 8.7 and 19.7 billion CNY, respectively. Meanwhile, the N deposition considerably reduced by 10 and 13 kgN/ha·yr. However, the YRD region could still simultaneously obtain substantial amounts of PM_2.5 and N deposition mitigation using the strategy proposed herein. The expanded optimization system can be directly adopted by policymakers to implement coordinated control in regions or countries facing the same NH₃ control conundrum.

Increases in ozone-related mortality in China over 2013-2030 attributed to historical ozone deterioration and future population aging

We systematically examine historical and future changes in premature respiratory mortalities attributable to ozone (O₃) exposure (O₃-mortality) in China and identify the leading cause of respective change for the first time. The historical assessment for 2013-2019 is based on gridded O₃ concentrations generated by a multi-source-data-fusion algorithm; the future prediction for 2019-2030 uses gridded O₃ concentrations projected by four Coupled Model Intercomparison Project Phase 6 (CMIP6) models under three Shared Socioeconomic Pathways (SSP) scenarios. During 2013-2019, national annual O₃-mortality is 176.3 thousand (95%CI: 123.5-224.0 thousand) averaged over 2013-2019 with an increasing trend of 14.1 thousand yr^-1 (95%CI: 10.2-17.4 thousand yr^-1); sensitivity experiments show that the O₃-mortality varies at a rate of +12.7 (95%CI: 9.2-15.6), +5.8 (95%CI: 4.0-7.4), +1.0 (95%CI: 0.7-1.2), -5.4 (95%CI: -6.9 to -3.7) thousand yr^-1, owing to changes in O₃ concentration, population age structure, population size, mortality rate for respiratory disease, respectively. The deterioration of O₃ air quality, shown as significant increase in O₃ concentration, is identified as the primary factor which contributes 90.1 % of 2013-2019 O₃-mortality rise. Compared with O₃-mortality estimated in this study, the widely-used O₃-mortality assessment method based on urban-site-dominant O₃ measurements generates close national O₃-mortality but overestimates (underestimates) provincial O₃-mortality in coastal (central) provinces. From 2019 to 2030, national O₃-mortality is projected to increase by 50.4-103.7 thousand under different SSP scenarios. The change in age structure (i.e. population aging) alone will result in significant O₃-mortality rises of 137.9-160.5 thousand. Compared with 2013-2019 rapid O₃ increase (+2.5 μg m^-3 yr^-1 at national level), O₃ concentrations are projected to increase at a lower rate (+0.4 μg m^-3 yr^-1 in SSP5-8.5) or even decrease (-0.7 μg m^-3 yr^-1 in SSP1-2.6) from 2019 to 2030. Therefore, population aging, in place of O₃ air quality deterioration, will become the leading cause of future O₃-mortality rises during the coming decade.

Variability of PM2.5 and O3 concentrations and their driving forces over Chinese megacities during 2018-2020

Recently, air pollution especially fine particulate matters (PM_2.5) and ozone (O₃) has become a severe issue in China. In this study, we first characterized the temporal trends of PM_2.5 and O₃ for Beijing, Guangzhou, Shanghai, and Wuhan respectively during 2018-2020. The annual mean PM_2.5 has decreased by 7.82%-33.92%, while O₃ concentration showed insignificant variations by -6.77%-4.65% during 2018-2020. The generalized additive models (GAMs) were implemented to quantify the contribution of individual meteorological factors and their gas precursors on PM_2.5 and O₃. On a short-term perspective, GAMs modeling shows that the daily variability of PM_2.5 concentration is largely related to the variation of precursor gases (R = 0.67-0.90), while meteorological conditions mainly affect the daily variability of O₃ concentration (R = 0.65-0.80) during 2018-2020. The impact of COVID-19 lockdown on PM_2.5 and O₃ concentrations were also quantified by using GAMs. During the 2020 lockdown, PM_2.5 decreased significantly for these megacities, yet the ozone concentration showed an increasing trend compared to 2019. The GAMs analysis indicated that the contribution of precursor gases to PM_2.5 and O₃ changes is 3-8 times higher than that of meteorological factors. In general, GAMs modeling on air quality is helpful to the understanding and control of PM_2.5 and O₃ pollution in China.

County level study of the interaction effect of PM2.5 and climate sustainability on mortality in China

Introduction

PM2.5 and climate change are two major public health concerns, with majority of the research on their interaction focused on the synergistic effect, particularly for extreme events such as hot or cold temperatures. The climate sustainability index (CLS) was introduced to comprehensively explore the impact of climate change and the interactive effect on human health with air pollution.

Methods

In this study, a county-level panel data in China was collected and used. The generalized additive model (GAM) and geographically and temporally weighted regression (GTWR) was used to explore the interactive and spatial effect on mortality between CLS and PM2.5.

Results and discussions

Individually, when CLS is higher than 150 or lower than 50, the mortality is higher. Moreover, when PM2.5 is more than 35 μg/m3, the influence on mortality is significantly increased as PM2.5 concentration rises; when PM2.5 is above 70 μg/m3, the trend is sharp. A nonlinear antagonistic effect between CLS and PM2.5 was found in this study, proving that the combined adverse health effects of climate change and air pollution, especially when CLS was lower (below 100) and PM2.5 was higher (above 35 μg/m3), the antagonistic effect was much stronger. From a spatial perspective, the impact of CLS and PM2.5 on mortality varies in different geographical regions. A negative and positive influence of CLS and PM2.5 was found in east China, especially in the northeastern and northern regions, -which were heavily polluted. This study illustrated that climate sustainability, at certain level, could mitigate the adverse health influence of air pollution, and provided a new perspective on health risk mitigation from pollution reduction and climate adaptation.

Assessment of indoor air quality and their inter-association in hospitals of northern India-a cross-sectional study

This study was commenced to evaluate the indoor and outdoor air quality concentrations of PM_2.5, sub-micron particles (PM_>2.5, PM_1.0-2.5, PM_{0.50 -1.0}, PM_0.25-0.50, and PM_<0.25), heavy metals, and microbial contaminants along with their identification in three different hospitals of Lucknow City. The study was conducted from February 2022 to April 2022 in hospitals situated in the commercial, residential, and industrial belts of the city. The indoor concentration trend of particulate matter as observed during the study suggested that most of the highest concentrations belonged to the hospital situated in an industrial area. The highest obtained indoor and outdoor concentrations for PM_1.0-2.5, PM_0.50-1.0, PM_0.25-0.50, and PM_<0.25 are 40.44 µg/m³, 56.08 µg/m³, 67.20 µg/m³, 74.50 µg/m³, 61.9 µg/m³, 79.3 µg/m³, 82.0 µg/m³, and 93.9 µg/m³, respectively, which belonged to hospital C situated in the industrial belt. However, for PM_>2.5, the highest indoor concentration obtained belonged to hospital B, i.e., 30.7 µg/m³, which is situated in the residential belt of the city. Regarding PM_2.5, the highest indoor and outdoor concentrations obtained are 149.41 µg/m³ and 227.45 µg/m³, which were recorded at hospital A and hospital C, respectively. The present study also observed that a high bacterial load of 1389.21 CFU/m³ is recorded in hospital B, and the fungi load was highest in hospital C with 786.34 CFU/m³. Henceforth, the present study offers thorough information on the various air pollutants in a crucial indoor setting, which will further aid the researchers in the field to identify and mitigate the same more precisely.

Synergetic PM2.5 and O3 control strategy for the Yangtze River Delta, China

PM_2.5 concentrations have dramatically reduced in key regions of China during the period 2013-2017, while O₃ has increased. Hence there is an urgent demand to develop a synergetic regional PM_2.5 and O₃ control strategy. This study develops an emission-to-concentration response surface model and proposes a synergetic pathway for PM_2.5 and O₃ control in the Yangtze River Delta (YRD) based on the framework of the Air Benefit and Cost and Attainment Assessment System (ABaCAS). Results suggest that the regional emissions of NOx, SO₂, NH₃, VOCs (volatile organic compounds) and primary PM_2.5 should be reduced by 18%, 23%, 14%, 17% and 33% compared with 2017 to achieve 25% and 5% decreases of PM_2.5 and O₃ in 2025, and that the emission reduction ratios will need to be 50%, 26%, 28%, 28% and 55% to attain the National Ambient Air Quality Standard. To effectively reduce the O₃ pollution in the central and eastern YRD, VOCs controls need to be strengthened to reduce O₃ by 5%, and then NOx reduction should be accelerated for air quality attainment. Meanwhile, control of primary PM_2.5 emissions shall be prioritized to address the severe PM_2.5 pollution in the northern YRD. For most cities in the YRD, the VOCs emission reduction ratio should be higher than that for NOx in Spring and Autumn. NOx control should be increased in summer rather than winter when a strong VOC-limited regime occurs. Besides, regarding the emission control of industrial processes, on-road vehicle and residential sources shall be prioritized and the joint control area should be enlarged to include Shandong, Jiangxi and Hubei Province for effective O₃ control.

Secondary PM2.5 dominates aerosol pollution in the Yangtze River Delta region: Environmental and health effects of the Clean air Plan

The Clean Air Plan has been active in China since 2013 to mitigate severe PM_2.5 pollution. In this study, we applied the air quality model WRF-Chem to simulate PM_2.5 in the Yangtze River Delta (YRD) region of China in 2017, with the aim of assessing the air quality improvement and its associated health burden in the final year of the Clean Air Plan. To better describe the fate of various PM_2.5 compositions, we updated the chemical mechanisms in the model beforehand, including heterogeneous sulfate reactions, aqueous secondary organic aerosol (SOA) uptake, and volatility basis set (VBS) based SOA production. Both the observation and simulation results agreed that the stringent clear air action effectively reduced the PM_2.5 pollution levels by ∼ 30 %. The primary PM_2.5 (-6 ∼  - 16 % yr^-1) showed a more significant decreasing trend than the secondary PM_2.5 (-2 ∼  - 8 % yr^-1), which was mainly caused by the directivity of the clear air actions and the worsening ozone pollution in the recent years. The inconsistent decreasing trends of PM_2.5 components subsequently led to an increasing proportion of secondary PM_2.5. Nitrate particles, higher in the central and western YRD region, have replaced sulfate and have become the largest component of secondary inorganic aerosols year-round, except in summer, when strong ammonium nitrate evaporation occurs. In addition, SOA remains an important component (21 ∼ 22 %) especially in summer, most of which is produced from the oxidation and ageing of semi/intermediate volatile organic compounds (S/IVOC). Furthermore, we quantified the associated health impacts and found that the Clean Air Plan has largely reduced premature mortality due to PM_2.5 exposure in the YRD region from 399.1 thousand to 295.7 thousand. Our study highlights the benefits of the Clean Air Plan and suggests that subsequent PM_2.5 improvement should be geared more towards controlling secondary pollutants.

Characteristics of Air Pollutants Emission and Its Impacts on Public Health of Chengdu, Western China

Pollution caused by PM_2.5 and O₃ are common environmental problems which can easily affect human health. Chengdu is a major central city in Western China, and there is little research on the regional emissions and health effects of air pollution in Chengdu. According to the Multi-resolution Emissions Inventory of the Chinese Model, 2017 (MEIC v1.3), this study compiled the air pollutant emission inventory of Chengdu. The results show that the pollutant emission of Chengdu is generally higher in winter than in summer. The southeast area of Chengdu is the key area where emissions of residential and industrial sectors are dominant. Through air quality simulation with a Weather Research and Forecasting model, coupled with the Community Multiscale Air Quality (WRF-CMAQ), the health effects of PM_2.5 and O₃ in winter and summer in Chengdu of 2017 were investigated. The primary pollutant in winter is PM_2.5 and O₃ in summer. PM_2.5 pollution accounted for 351 deaths in January and July 2017, and O₃ pollution accounted for 328 deaths in the same period. There were 276 deaths in rural areas and 413 in urban areas. In January and July 2017, the health economic loss caused by PM_2.5 accounted for 0.0974% of the gross regional product (GDP) of Chengdu in 2017, and the health economic loss caused by O₃ accounted for 0.0910%.

How the Air Clean Plan and carbon mitigation measures co-benefited China in PM2.5 reduction and health from 2014 to 2020

China implemented a stringent Air Clean Plan (ACP) since 2013 to address environmental and health risks caused by ambient fine particulate matter (PM_2.5). However, the policy effectiveness of ACP and co-benefits of carbon mitigation measures to environment and health are still largely unknown. Using satellite-based PM_2.5 products produced in our previous study, concentration-response functions, and the logarithmic mean Divisia index (LMDI) method, we analyzed the spatiotemporal dynamics of premature deaths attributable to PM_2.5 exposure, and quantitatively estimated the policy benefits of ACP and carbon mitigation measures. We found the annual PM_2.5 concentrations in China decreased by 33.65 % (13.41 μg m^-3) from 2014 to 2020, accompanied by a decrease in PM_2.5-attributable premature deaths of 0.23 million (95 % confidence interval (CI): 0.22-0.27), indicating the huge benefits of China ACP for human health and environment. However, there were still 1.12 million (95 % CI: 0.79-1.56) premature deaths caused by the exposure of PM_2.5 in mainland China in 2020. Among all ACP measures, clean production (contributed 55.98 % and 51.14 % to decrease in PM_2.5 and premature deaths attributable to PM_2.5) and energy consumption control (contributed 32.58 % and 29.54 % to decrease in PM_2.5 and premature deaths attributable to PM_2.5) made the largest contribution during the past seven years. Nevertheless, the environmental and health benefits of ACP are not fully synergistic in different regions, and the effectiveness of ACP measures reduced from 2018 to 2020. The co-effects of CO₂ and PM_2.5 has become one of the major drivers for PM_2.5 and premature deaths reduction since 2018, confirming the clear environment and health co-benefits of carbon mitigation measures. Our study suggests, with the saturation of clean production and source control, more targeted region-specific strategies and synergistic air pollution-carbon mitigation measures are critical to achieving the WHO's Air Quality Guideline target and the UN's Sustainable Development Goal Target in China.

Coordinated effects of energy transition on air pollution mitigation and CO2 emission control in China

China has made progress in energy transition to improve air quality, but still confronts challenges including further ambient PM_2.5 reduction, O₃ pollution mitigation, and CO₂ emission control. To explore the coordinated effects of energy transition on air quality and carbon emission in the near term in China, we designed 4 scenarios in 2025 based on different projections of energy transition progress with varying end-of-pipe control level, in each of which we calculated emissions of major air pollutants and CO₂, and simulated ambient PM_2.5 and O₃ concentrations. Results show that energy transition has disparate effects on emission reduction of different air pollutants and sectors, which largely depends on their current end-of-pipe control levels. The different effects on emission reduction may result in opposite variation tendencies of ambient PM_2.5 and O₃ concentration in a future scenario with aggressive energy transition policies and end-of-pipe control level in 2018. With the end-of-pipe control level strengthened in 2025, PM_2.5 and O₃ concentration could both reduce on the national scale, but the reduction of ambient O₃ lags behind PM_2.5, indicating the difficulty of O₃ pollution control. As to CO₂, national emission would go up in 2025 either implementing current or aggressive energy transition policies due to growing needs of electricity and on-road transportation, but emissions in most provinces could decline to below the 2018 level with aggressive energy transition policies because of substitution of clean energy in industrial, residential and off-road transportation sectors. The study results suggest strictly implementing restrictive end-of-pipe control measures along with energy transition to simultaneously reduce ambient PM_2.5 and O₃ concentration, and accelerating substitution of renewable energy in power sectors where electricity generation grows rapidly to synergistically control air pollution and CO₂ emissions. Furthermore, the projection of CO₂ emissions could provide references for short-term emission control targets from the perspective of air quality improvement.

Increasing life expectancy in China by achieving its 2025 air quality target

China is striving to build a "Beautiful China" characterized by clean air. The country has committed to further reducing its national mean fine particle (PM2.5) concentration by 10% from 2020 to 2025, following the substantial improvements in its air quality during the past decade. Meanwhile, the "Healthy China" mission has pledged to increase the national mean life expectancy by one year during the same period. Yet, to what extent will the "Beautiful China" mission contribute to the "Healthy China" vision by reducing the levels of the detrimental PM2.5 is still unclear. Here, by coupling the life table approach and an epidemiological concentration-response model, this study quantifies the potential benefits of achieving China's 2025 air quality target on the national life expectancy. The analysis reveals that the Chinese citizen could expect to extend the average life expectancy by 42.5 days by 2025 due to improved air quality. In addition, if the Chinese government outperforms the planned air quality target, as it usually does, the gains would increase to 65.4 days, ∼18% of the "Healthy China" life expectancy increment task. Further reductions in PM2.5 concentration would lead to accelerated gains in life expectancy both nationally and at the city level, providing strong incentives for the authorities to keep improving air quality. This study reveals the notable benefits on individual life that could be expected from air quality improvement in China and suggests that longer life expectancy is achievable by implementing a health-prioritized air quality management mechanism.