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

Assessment of sulfate and nitrate variations in China during 19902020: Insights into source contributions and formation pathways

Sulfate (SO42-) and nitrate (NO3-) are two critical constituents of fine particulate matter (PM2.5), significantly impacting air quality and public health. This study provides a comprehensive assessment of spatial and temporal variations in SO42- and NO3- levels across China from 1990 to 2020 by using a revised Community Multiscale Air Quality Modeling System (CMAQ), focusing on elucidating insights into source contributions and formation pathways. The results reveal that NO3- pollution has become increasingly significant, with its concentrations surpassing those of SO42- in most regions of China since 2017. Industrial emissions were identified as the primary contributors to SO42- levels, accounting for 40.2 %57.5 % in Beijing-Tianjin-Hebei region (BTH), 51.0 %76.6 % in Yangtze River Delta (YRD), 46.8 %68.2 % in Pearl River Delta (PRD), 38.9 %62.8 % in Sichuan Basin (SCB), and 36.1 %58.8 % in Fenwei Plain (FWP). For NO3-, industrial emissions were predominant in BTH (27.7 %33.1 %) and YRD (31.0 %33.6 %), while transportation emissions were the major source in PRD (26.4 %36.3 %), in SCB and FWP, contributions from these sectors were comparable. The formation pathways of SO42- exhibited distinct regional variations: overall, primary emission of SO42- was the predominant pathway in BTH (23.7 %47.3 %) and YRD (24.1 %30.5 %), heterogeneous reaction dominated in SCB (23.2 %55.5 %) and FWP (20.5 %48.9 %), and aqueous-phase oxidation reaction of SO2 by H2O2 was the leading formation pathway in PRD (23.6 %32.8 %). In contrast, the formation pathways of NO3- demonstrated consistency across all regions, with combined gas-phase oxidation reaction of NO2 by OH and the heterogeneous reaction of N2O5 accounting for over 90 % of its production. This study highlights the need for targeted air quality management strategies that account for regional variations in source contributions and prioritize the reduction of key oxidants driving secondary aerosol formation. The findings could offer valuable insights for policymakers developing effective measures to mitigate air pollution.

Evaluating the health impact of air pollution control strategies and synergies among PM2.5 and O3 pollution in Beijing-Tianjin-Hebei region, China

Since 2013, China has implemented a series of strict Air Pollution Control Strategies (APCS) to mitigate environmental and health risks associated with ambient fine particulate matter (PM2.5). However, while APCS sets clear targets for PM2.5 concentration, it lacks quantitative control over O3 levels. Most existing studies have focused on nation-wide health assessments. Therefore, by conducting a coupled framework using health assessment and decomposition method, the spatiotemporal variation in deaths attributable to PM2.5 pollution, as well as the role of APCS and the synergies between PM2.5 and O3 on PM2.5 concentration and health impacts in the Beijing-Tianjin-Hebei (BTH) region have been explored. The result showed that: (1) PM2.5 concentration in the BTH region decreased by 68.2%, with a reduction of 45,833 (95% Confidence Interval [CI]: 33,808, 50,069) deaths over the period. However, both concentrations and mortality remained high, indicating a need for faster reductions. (2) End-of-pipe control contributed the most to reducing PM2.5 concentrations and deaths, though the gaps between source control and end-of-pipe control is narrowing. (3) The synergistic effects of O3 and PM2.5 in reducing concentration and mortality have increased, becoming a significant driver of PM2.5-related health impacts. Our study emphasizes the future importance of implementing refined, diverse emission reduction measures and coordinating efforts to reduce both O3 and PM2.5 emissions, which are crucial for achieving the Sustainable Development Goals (SDGs) and advancing the "Beautiful China" and "Healthy China" initiatives.

Mapping multilevel adaptation response to protect maternal and child health from climate change impacts: A scoping review

Anthropogenic climate change attributed increases in air pollution, rising temperatures, and extreme weather events are linked to a higher risk of adverse pregnancy and birth outcomes, necessitating interventions to protect maternal and child health. This scoping review mapped multilevel adaptation strategies implemented to protect maternal and child health from climate change effects. Eighteen unique adaptation strategies we identified included educational interventions, risk communication, air purifiers, air cleaning strategies, nutrition supplementation, cash transfer, employment guarantee scheme, community health worker program, chemoprophylaxis, insecticide-treated nests, home and environmental remediation, and bioethanol cooking fuel. Our findings suggest that these adaptation strategies are generally nonspecific and fail to address the specialized needs and unique health risks faced by pregnant women and young children. Prioritizing the involvement of pregnant women, mothers of young children and local healthcare services in developing tailored adaptation interventions is crucial to support climate change adaptation, resilience, and reducing maternal and child health risks.

Synergistic effects of CO2 and air pollutants from ship emissions in Shanghai, China: Spatial-temporal characteristics, prediction assessment, policy implications

Currently, the goal of achieving net-zero emissions for ships presents a significant challenge to CO2 reduction policies. A comprehensive analysis of ship air pollutants and CO2 emissions is crucial for mitigating greenhouse effect and air pollution. To realize the overall control policies of ship emissions, this study established a high-resolution emissions inventory for air pollutants (CO, HC, NOx, PM2.5, PM10, SO2) and CO2 from 11 types of ships in Shanghai, and conducted analyses of spatiotemporal characteristics, spatial heterogeneity and consistency, and synergistic effects. Results indicated significant monthly and weekly variability in ship emissions. Due to the varying contribution rates of large ocean-going vessels, the temporal-spatial distributions of CO, HC, NOx, and CO2 revealed significant differences compared to PM2.5, PM10, and SO2. CO2 had a positive synergy in emissions with CO, HC, NOx according to the spatial heterogeneity and consistency analysis. Phasing out of old ships and implementing carbon capture technology were more conducive to CO2 reduction, while the replacement of clean energy contributed greater potential in reducing air pollutant emissions. Comprehensive mitigation measures hold effective co-benefits in air pollutants and CO2 reductions, with the synergistic effect index approaching 1. The implementation of strengthened control measures would minimize the ship emissions, achieving a 78.1% reduction in CO2, and have a positive long-term effect on co-control emission reduction. This study combines high-precision analysis, prediction assessment, and synergistic effects, providing a reference for the development of refined ship management policies in megacities worldwide.

Synergies of air pollution control policies: A review

Air pollution control necessitates the implementation of multiple policy instruments in a coordinated manner. However, the enforcement of different policy combinations may generate complementary or offsetting synergistic effects, thereby influencing policy effectiveness. Nevertheless, the direction of synergy and the mechanisms of action among heterogeneous policies is undefined in existing academic research. This study systematically reviewed 773 articles from 1998 to 2023 and, for the first time, integrated four primary domains of air pollution control policies: policy synergy and integration, collaborative governance for pollution and carbon mitigation, joint control of multiple pollutants, and cross-regional cooperative governance. This study revealed the directions and mechanisms of air policy synergy and provided empirical evidence for cross-regional comparisons in global environmental governance, with the ultimate goal of enhancing the effectiveness of air pollution control policies. Specifically, the mechanisms underlying policy synergy suggest that the cumulative impact of policies leads to the synergistic effects of multiple policies being superior to the effects of implementing a single policy. Furthermore, due to market price signals or the characteristics of specific technologies, the concurrent application of multiple policies may occasionally yield negative synergistic outcomes. Despite these advancements, gaps remain particularly in broadening the scope of policy integration, refining the assessment of synergistic effects, developing control strategies, and enhancing stakeholder engagement. Further research is necessary to address these gaps and enhance air policy effectiveness.

New mechanisms of PM2.5 induced atherosclerosis: Source dependent toxicity and pathogenesis

Exposure to fine particulate matter (PM2.5) is recognized to induce atherosclerosis, but the underlying mechanisms are not fully understood. This study used ambient PM2.5 samples collected in one of the highly polluted regions of Guanzhong Plain in China (2017-2020) and an ApoE-/- mouse model to investigate the association between exposure to PM2.5 and atherosclerosis. Despite a substantial decrease in the ambient concentration of PM2.5 from 266.7 ± 63.9 to 124.4 ± 37.7 μg m-3 due to the execution of a series of emission controls, cardiovascular toxicity due to exposure to PM2.5 remained at a significantly high level compared with the Control group. Moreover, the result highlighted that biomass burning (BB) showed an increased contribution to PM2.5 while most anthropogenic sources decreased. This study found that PM2.5 exposure led to vascular oxidative stress and inflammation, accelerated atherosclerotic plaque growth, and altered vascular proliferation pathways. The latter two mechanisms provide new insights into how PM2.5 enhanced the processes of atherosclerosis, promoted lipoprotein cholesterol (LDL-C) absorption in vascular cells, and directed stimulation of cell function factors (VEGF and MCP-1), which are highly associated by PI3K/AKT signaling pathway. Polycyclic aromatic hydrocarbons (PAHs) and their derivatives, and certain biomarkers showed strong correlations with bio-reactivity, while BB was identified as a major contributor to toxicity of PM2.5. The findings offer new insights into the role of PM2.5 promoting atherosclerosis and provide recommendations for controlling PM2.5 pollution to prevent and treat the disease particularly for susceptible populations.

Emission reduction strategies and health: a systematic review on the tools and methods to assess co-benefits

OBJECTIVE

The objective of this study is to review the current literature on the health co-benefits of emission reduction strategies and the methods and tools available to assess them.

DESIGN

Systematic review conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

DATA SOURCES

PubMed, Scopus, Web of Science, ScienceDirect and GreenFILE were searched from January of 2017 to March of 2023.

ELIGIBILITY CRITERIA

We included original, peer-reviewed journal articles that described emission (ambient air pollutant and greenhouse gases) reduction strategies and assessed their health co-benefits.

DATA EXTRACTION AND SYNTHESIS

Two independent reviewers employed standardised methods to search, screen and code the included studies, documenting their findings in an Excel spreadsheet.

RESULTS

From 6687 articles, 82 were included. Most studies show that emissions reduction strategies improve air quality, reducing mortality and morbidity. Health risk assessment and health impact assessment are common, though procedures may cause confusion. About 33% used established models like the integrated exposure-response and global exposure mortality model. Out of all studies, 16% of them used Environmental Benefits Mapping and Analysis Program-Community Edition. Only 17.8% carried out cost-benefit analyses, but these show economic worth in investing in emission reduction strategies.

CONCLUSIONS

Emission reduction strategies significantly enhance human health, with potential co-benefits offsetting intervention costs, which can be an incentive for action in low and middle-income countries. This review emphasises investing in cost-benefit analyses and research, particularly in regions with limited studies on emission reduction and health co-benefits. It provides decision-makers insights into selecting assessment methods and underscores the ongoing need for model and tool evaluation.

PROSPERO REGISTRATION NUMBER

CRD42022332480.

Hidden hazards behind coal cleaning technology: Unintended health deteriorations amid China's air quality improvements

The "Air Pollution Prevention and Control Action Plan" was implemented by the Chinese government in 2013 to promote the adoption of clean coal technology, successfully led to a significant enhancement in air quality. However, it may have inadvertently shifted pollution from the downstream to the upstream stages of the coal life cycle, leading to unobserved adverse environmental impacts due to the improper treatment of coal-washing wastewater. Consequently, residents in China's coal-production areas may be vulnerable to notable health risks due to intensified coal-washing activities. This study is the first empirical analysis that utilizes real-world microdata, employing a difference-in-differences model to uncover a significant decline in children's health in China's largest coal-production area. It found increases of 7.2 % and 6.3 % in the frequency and probability of hospital visits, respectively. In rural areas, there were increases of 9.5 % and 7.7 %, respectively. Furthermore, in rural areas where people prefer sons over daughters, the observed effects for girls were significantly higher, at 11.8 % and 13 %, respectively. These results indicate that the rapid expansion of clean coal technology could have considerable adverse effects on public health, highlighting the critical need for meticulous management and supervision of related technologies to effectively mitigate potential health risks.

Significant lead isotope 'fractionation' in maize records plant lead uptake, transfer, and detoxification mechanisms

Lead isotope analysis is the main method to trace the sources and cycling of Pb in the biosphere system. The linchpin of such application hinges on the assumption that there is negligible or no biologically mediated isotopic fractionation of Pb occurs in the environment. However, recent measurements by high-precision multi-collector mass spectrometry revealed that biological isotope fractionation of heavy mass elements is a prevalent phenomenon. This study shows that compared with the Pb sources, the maize plant (Zea mays L.) organs exhibit a wider range of Pb isotope compositions and a depletion of radioactive Pb isotopes (206Pb, 207Pb, and 208Pb). Moreover, three independent studies consistently indicate that the 206Pb/207Pb ratio of maize organs varies as root/leaf > stem/grain, reflecting a continuous loss of light Pb isotopes during transportation. The conventional wisdom fails to account for these phenomena, suggesting that maize may undergo Pb isotope fractionation during the absorption and transportation of Pb. However, compared with other non-traditional metal isotopes, Pb isotope exhibits a more significant fractionation magnitude. We tentatively attribute this fractionation to the Pb tolerance mechanism of maize and its selective absorption of various forms of Pb, which requires further research to validate. Findings from this study mandate caution in future Pb source tracing in plants using Pb isotope methods and open up applications in using Pb isotopic fractionation to track Pb uptake and transfer pathways and decipher the associated detoxification mechanisms in plants.

Understanding air pollution reduction from the perspective of synergy with carbon mitigation in China from 2008 to 2017

In response to the dual challenges of air pollution control and carbon mitigation, China has strategically shifted its focus towards the synergistic reduction of air pollutants and CO2 emissions. This study identifies the potential areas and specific air pollutant species (including CO, NOx, and SO2) for co-reduction with carbon mitigation. We also reveal the driving forces behind the emissions of each air pollutant at both the national and regional scales. Our findings are as follows: (1) The potential for synergistic reduction of CO and SO2 with CO2 emissions has diminished in economically developed areas. There is a significant opportunity for co-reduction of SO2 and CO2 in the western and northern regions of China, particularly within Heilongjiang Province. (2) NOx is the key species for synergistic reduction with CO2 emissions across China, especially in the Chengyu Plain. (3) Cleaner production and the synergistic reduction effect are the primary contributors to national air pollutant reduction in China from 2008 to 2017. Conversely, efforts in economic development and energy efficiency have led to emission increases. Energy and industrial structures have only made limited contributions to emission reductions, and carbon mitigation shows an inhibition effect on emission reductions. These results offer valuable insights for developing targeted regional strategies for deeper air pollution control, considering the specific characteristics and needs of each region. Additionally, our findings highlight the importance of addressing policy misalignments and strengthening mutual-influence mechanisms between air pollution control and carbon mitigation, ensuring that policies for carbon reduction also effectively contribute to air quality improvements.

Uncovering the differentiated impacts of carbon neutrality and clean air policies in multi-provinces of China

Ambitious action plans have been launched to address climate change and air pollution. Through coupling the IMED|CGE, GAINS, and IMED|HEL models, this study investigate the impacts of implementing carbon neutrality and clean air policies on the energy-environment-health-economy chain in the Beijing-Tianjin-Hebei-Henan-Shandong-Shanxi region of China. Results show that Shandong holds the largest reduction in energy consumption and carbon emissions toward the 1.5°C target. Shandong, Henan, and Hebei are of particularly prominent pollutant reduction potential. Synergistic effects of carbon reduction on decreasing PM2.5 concentration will increase in the future, specifically in energy-intensive regions. Co-deployment of carbon reduction and end-of-pipe technologies are beneficial to decrease PM2.5-related mortalities and economic loss by 4.7-12.9% in 2050. Provincial carbon reduction cost will be higher than monetary health benefits after 2030, indicating that more zero-carbon technologies should be developed. Our findings provide scientific enlightenment on policymaking toward achieving carbon reduction and pollution mitigation from multiple perspectives.

A novel framework for quantitative attribution of particulate matter pollution mitigation to natural and socioeconomic drivers

Quantifying drivers contributing to air quality improvements is crucial for pollution prevention and optimizing local policies. Despite advances in machine learning for air quality analysis, their limited interpretability hinders attribution on global and local scales, vital for informed city management. Our study introduces an innovative framework quantifying socioeconomic and natural impacts on mitigation of particulate matter pollution in 31 Chinese major cities from 2014 to 2021. Two indices, formulated based on the additivity of Shapley additive explanations, are proposed to measure driver contributions globally and locally. Our analysis explores the self-contained and interactive effects of these drivers on particulate levels, pinpointing critical threshold values where these drivers trigger shifts in particulate matter levels. It is revealed that SO2, NOx, and dust emission reductions collectively account for 51.58 % and 51.96 % of PM2.5 and PM10 decreases at the global level. Moreover, our findings unveil a significant heterogeneity in driver contributions to pollutant mitigation across distinct cities, which can be instrumental in crafting location-specific policy recommendations.

Multi-timescale variation characteristics of PM2.5 in different regions of China during 2014-2022

Over the past decade, China has achieved a significant reduction in PM2.5 concentrations. Due to the diversity of natural and artificial factors, regional differences are remarkable in the variation characteristics and have not been well addressed in previous studies. Based on hourly observed PM2.5 concentrations from 2014 to 2022, this study conducted a comprehensive analysis of variation characteristics on annual, seasonal, and diurnal scales, with a special focus on differences across major regions. Driving factors of the variations, the effectiveness of air pollution control efforts as well as future priorities were discussed. The annual PM2.5 concentrations in all regions showed an overall downward trend from 2014 to 2022, but the decline rates differed notably across the regions, with the maximum value nearly two times higher than the minimum value. The seasonal decline rates also differ from region to region, which could be partially attributed to the burning of crop residues and dust events. Northeast China was significantly affected by the burning of crop residues and experienced a big drop in the number of fire points in autumn, but a remarkable increase in spring. The spring dust events may greatly contribute to PM2.5 concentrations in northern and western China. For diurnal variation, nighttime concentrations were generally greater than daytime concentrations, and the nighttime concentrations were likely to increase in eastern regions and decrease in western regions. Furthermore, the daytime and nighttime ratios (calculated by daytime/nighttime concentration divided by the daily-mean concentration) exhibited different interannual trends, with the daytime ratios decreasing and nighttime ratios increasing, especially in the northeastern and western regions. The findings indicate that the air pollution control efforts have been generally successful, but with large regional disparities, and highlight the importance of controlling crop residue burning, dust events, and nighttime emissions for specific seasons and regions.

Interpreting Highly Variable Indoor PM2.5 in Rural North China Using Machine Learning

Household air pollution associated with solid fuel use is a long-standing public concern. The global population mainly using solid fuels for cooking remains large. Besides cooking, large amounts of coal and biomass fuels are burned for space heating during cold seasons in many regions. In this study, a wintertime multiple-region field campaign was carried out in north China to evaluate indoor PM2.5 variations. With hourly resolved data from ∼1600 households, key influencing factors of indoor PM2.5 were identified from a machine learning approach, and a random forest regression (RFR) model was further developed to quantitatively assess the impacts of household energy transition on indoor PM2.5. The indoor PM2.5 concentration averaged at 120 μg/m3 but ranged from 16 to ∼400 μg/m3. Indoor PM2.5 was ∼60% lower in families using clean heating approaches compared to those burning traditional coal or biomass fuels. The RFR model had a good performance (R2 = 0.85), and the interpretation was consistent with the field observation. A transition to clean coals or biomass pellets can reduce indoor PM2.5 by 20%, and further switching to clean modern energies would reduce it an additional 30%, suggesting many significant benefits in promoting clean transitions in household heating activities.

Strategies for the coordinated control of particulate matter and carbon dioxide under multiple combined pollution conditions

Air pollutants represented by fine particulate matter (PM2.5) and the greenhouse effect caused by carbon dioxide (CO2), are both urgent threats to public health. Tackling the synergistic reduction of PM2.5 and CO2 is critical to achieving improvements in clean air worldwide. A persistent issue is the identification of their common sources and integrated impacts under different environmental conditions. In this study, we investigated the characteristics of the pollution types captured by combined analysis through a comprehensive observational dataset for 2017-2020, and applied machine learning algorithms to quantify the effects of drivers on air pollutants and CO2 formation. More importantly, detailed conclusions were drawn for the joint control of PM2.5-CO2 in multiple pollution types by using ensemble traceability technique. We demonstrated that reducing coal combustion emissions was an effective measure to maximize the benefits of PM2.5-CO2 in weather with low CO2 levels and no PM2.5 pollution. Correspondingly, on days with severe PM2.5 episodes, prioritizing control of vehicle emissions can simultaneously mitigate PM2.5 and CO2. Similar conclusions were found at high CO2 levels, accompanied by a more extensive role of vehicle emissions. Furthermore, a comparison of the differences in source impacts between PM2.5-CO2 and individual species suggests that focusing only on the sources that contribute significantly to one species may result in an underestimation or overestimation of PM2.5-CO2 source impacts. One such implication, as evidenced by our findings, is that synergistic controlling common sources of pollutants should be efficient. Thereby, common source management targeting PM2.5-CO2 under multiple pollution types is a more workable solution to alleviate environmental pollution.

Toxicological Effects of Secondary Air Pollutants

Secondary air pollutants, originating from gaseous pollutants and primary particulate matter emitted by natural sources and human activities, undergo complex atmospheric chemical reactions and multiphase processes. Secondary gaseous pollutants represented by ozone and secondary particulate matter, including sulfates, nitrates, ammonium salts, and secondary organic aerosols, are formed in the atmosphere, affecting air quality and human health. This paper summarizes the formation pathways and mechanisms of important atmospheric secondary pollutants. Meanwhile, different secondary pollutants' toxicological effects and corresponding health risks are evaluated. Studies have shown that secondary pollutants are generally more toxic than primary ones. However, due to their diverse source and complex generation mechanism, the study of the toxicological effects of secondary pollutants is still in its early stages. Therefore, this paper first introduces the formation mechanism of secondary gaseous pollutants and focuses mainly on ozone's toxicological effects. In terms of particulate matter, secondary inorganic and organic particulate matters are summarized separately, then the contribution and toxicological effects of secondary components formed from primary carbonaceous aerosols are discussed. Finally, secondary pollutants generated in the indoor environment are briefly introduced. Overall, a comprehensive review of secondary air pollutants may shed light on the future toxicological and health effects research of secondary air pollutants.

Change in Air Quality during 2014-2021 in Jinan City in China and Its Influencing Factors

Air pollution affects climate change, food production, traffic safety, and human health. In this paper, we analyze the changes in air quality index (AQI) and concentrations of six air pollutants in Jinan during 2014-2021. The results indicate that the annual average concentrations of PM10, PM2.5, NO2, SO2, CO, and O3 and AQI values all declined year after year during 2014-2021. Compared with 2014, AQI in Jinan City fell by 27.3% in 2021. Air quality in the four seasons of 2021 was obviously better than that in 2014. PM2.5 concentration was the highest in winter and PM2.5 concentration was the lowest in summer, while it was the opposite for O3 concentration. AQI in Jinan during the COVID epoch in 2020 was remarkably lower compared with that during the same epoch in 2021. Nevertheless, air quality during the post-COVID epoch in 2020 conspicuously deteriorated compared with that in 2021. Socioeconomic elements were the main reasons for the changes in air quality. AQI in Jinan was majorly influenced by energy consumption per 10,000-yuan GDP (ECPGDP), SO2 emissions (SDE), NOx emissions (NOE), particulate emissions (PE), PM2.5, and PM10. Clean policies in Jinan City played a key role in improving air quality. Unfavorable meteorological conditions led to heavy pollution weather in the winter. These results could provide a scientific reference for the control of air pollution in Jinan City.