Role In PM2 Research Articles

Environmental technology to stimulate life expectancy: A deep dive into the role of PM2.5 and carbon emission

As the Latin American economies contend with improving public health while simultaneously dealing with ecological issues, understanding the determinant of life expectancy becomes imperative. This study explores the interaction among environmental technology, economic development, cleaner energy transitions, industrial growth, particulate Matter 2.5 (PM2.5), carbon emission, and their collective impact on life expectancy across Latin American nations. The research incorporates advanced econometric approaches comprising Mean Group (MG), Pooled Mean Group (PMG), and Method of Moments Quantile Regression (MMQR). The study’s outcome established that cleaner energy transitions, Gross Domestic Product (GDP), industrialization and environmental technologies significantly improve life expectancy, especially at higher quantiles. However, the outcome highlighted that PM2.5 and carbon emissions reduce life expectancy. Additionally, this study supports the unidirectional connection between environmental technology, economic development, cleaner energy transitions, industrial growth, life expectancy, and the bidirectional connection flowing from carbon emission PM2.5 to life expectancy. The study offers a roadmap for Latin America and global economies to invest in technology, cleaner power supply and industrialization to provide a route toward sustainable development and better public health that will eventually improve their citizens’ life expectancy.

The Possible Role of PM2.5 Chronic Exposure on 5-Year Survival in Patients with Left Ventricular Dysfunction Following Coronary Artery Bypass Grafting.

The survival benefit of surgical revascularization in multivessel coronary artery disease is well understood, though it can be modified by left ventricular dysfunction. Chronic exposure to air pollutants has gained more attention recently as a possible non-traditional morbidity and mortality cardiovascular risk factor. This study identified possible 5-year mortality risk factors related to postoperative left ventricular performance, including air pollutants. There were 283 patients (244 (86%) males) with a median age of 65 (60-70) years enrolled in the retrospective analysis. All patients were referred for off-pump coronary artery revascularization due to chronic coronary syndrome that presented as a multivessel coronary artery disease. They were divided into three groups depending on the postoperative course of left ventricular fraction (LVEF 50% or more (169 patients), LVEF between 41 and 49% (61 patients), and LVEF 40% or less (53 patients)). The overall survival rate was 84% (237 patients) in a median follow-up time of 5.3 (4.8-6.1) years. The median (Q1-Q3) chronic air pollution exposures for the analyzed group were 19.3 (16.9-22.4) μg/m3 for fine particles such as PM2.5, 25.8 (22.5-29.4) μg/m3 for coarse particles such as PM10, and 12.2 (9.7-14.9) μg/m3 for nitric dioxide (NO2). The mortality in the first group (LVEF at least 50%) was 23 (13.6%), in the second group (LVEF 41-49%) was 9 (15%), and in the third group (LVEF 40% or less) was 14 (26%). The multivariable regression analysis for the five-year mortality risk in the first group revealed the predictive value of dyslipidemia (HR: 3.254, 95% CI: 1.008-10.511, p = 0.049). The multivariable regression analysis for five-year mortality risk in the second group revealed the predictive value of dyslipidemia (HR: 3.391, 95% CI: 1.001-11.874, p = 0.050) and PM2.5 (HR: 1.327, 95% CI: 1.085-1.625, p = 0.006). In the third group (severely decreased LVEF), chronic PM2.5 exposure was found to be significant (HR: 1.518, 95% CI: 1.50-2.195, p = 0.026) for 5-year mortality prediction. Traditional risk factors, such as dyslipidemia, are pivotal in the 5-year mortality risk following surgical revascularization. Chronic exposure to ambient air pollutants such as PM2.5 may be an additional risk factor in patients with left ventricular dysfunction.

Global trends and hotspots in the study of the effects of PM2.5 on ischemic stroke

AimThe objective of this study was to visually analyse global research trends and hotspots regarding the role of PM2.5 in ischemic stroke.MethodsThe Web of Science core collection database was used to search the literature on PM2.5 and ischemic stroke from 2006 to 2024. Visualization analysis was conducted using CiteSpace, VOSviewer, and an online bibliometric platform.ResultsThe analysis comprises 190 articles published between 2006 and 2024 by 1229 authors from 435 institutions in 39 countries, across 78 journals. Wellenius GA has the highest number of published and cited papers. China has the highest number of papers, while Canada has the highest citation frequency. Capital Medical University published the highest number of papers, and Harvard University had the highest citation frequency for a single paper. The study investigated the impact of PM2.5 on ischemic stroke in three phases. The first phase analysed hospitalisation rates for correlations. The second phase utilised large-scale multi-cohort data from around the world. The third phase involved studying global exposure risk through machine learning and model construction. Currently, there is limited research on the mechanisms involved, and further in-depth investigation is required.ConclusionThis paper presents a bibliometric analysis of the research framework and hotspots concerning the effect of PM2.5 on ischemic stroke. The analysis aims to provide a comprehensive understanding of this field for researchers. It is expected that research on the effect of PM2.5 on ischemic stroke will remain an important research topic in the future.

The Influence of Three-Dimensional Building Morphology on PM2.5 Concentrations in the Yangtze River Delta

The rapid urbanization of urban areas in China has brought about great variation in the layout of cities and serious air pollution. Recently, the focus has been directed toward understanding the role of urban morphology in the generation and spread of atmospheric pollution, particularly in PM2.5 emissions. However, there have been limited investigations into the impact of three-dimensional (3D) features on changes in PM2.5 concentrations. By analyzing a wealth of data on building structures based on a mixed linear model and variance partition analysis in the Yangtze River Delta throughout 2018, this study sought to examine the associations between PM2.5 concentrations and urban building form, and further compared the contributions of two-dimensional (2D) and 3D building features. The findings revealed that both 2D and 3D building forms played an important role in PM2.5 concentrations. Notably, the greater contribution of 3D building forms on PM2.5 concentrations was observed, especially during the summer, where they accounted for 20% compared to 7% for 2D forms. In particular, the building height range emerged as a crucial local factor affecting PM2.5 concentrations, contributing up to 12%. Moreover, taller buildings with more variability in height were found to aid in the dispersion of pollution. These results underscore the substantial contribution of 3D building morphology to PM2.5 pollution, contrasting with previous studies. Furthermore, compact buildings were linked to lower pollution levels, and an urban landscape characterized by polycentric urban structures and lower fragmentation was deemed more favorable for sustainable urban development. This study is significant in investigating the contribution of 3D morphology to PM2.5 and its importance for pollution dispersion mechanisms. It suggests the adoption of a polycentric urban form with a broader range of building heights in urban planning for local governments in the Yangtze River Delta.

The Impact of Vertical Eddy Diffusivity Changes in the CMAQ Model on PM2.5 Concentration Variations in Northeast Asia: Focusing on the Seoul Metropolitan Area

The vertical eddy diffusion process plays a crucial role in PM2.5 prediction, yet accurately predicting it remains challenging. In the three-dimensional atmospheric chemistry transport model (3-D AQM) CMAQ, a parameter, Kz, is utilized, and it is known that PM2.5 prediction tendencies vary according to the floor value of this parameter (Kzmin). This study aims to examine prediction characteristics according to Kzmin values, targeting days exceeding the Korean air quality standards, and to derive appropriate Kzmin values for predicting PM2.5 concentrations in the DJFM Seoul Metropolitan Area (SMA). Kzmin values of 0.01, 0.5, 1.0, and 2.0, based on the model version and land cover, were applied as single values. Initially focusing on December 4th to 12th, 2020, the prediction characteristics were examined during periods of local and inflow influence. Results showed that in both periods, as Kzmin increased, surface concentrations over land decreased while those in the upper atmosphere increased, whereas over the sea, concentrations increased in both layers due to the influence of advection and diffusion without emissions. During the inflow period, the increase in vertically diffused pollutants led to increased inflow concentrations and affected contribution assessments. Long-term evaluations from December 2020 to March 2021 indicated that the prediction performance was superior when Kzmin was set to 0.01, but it was not significant for the upwind region (China). To improve trans-boundary effects, optimal values were applied differentially by region (0.01 for Korea, 1.0 for China, and 0.01 for other regions), resulting in significantly improved prediction performance with an R of 0.78, IOA of 0.88, and NMB of 0.7%. These findings highlight the significant influence of Kzmin values on winter season PM2.5 prediction tendencies in the SMA and underscore the need for considering differential application of optimal values by region when interpreting research and making policy decisions.

Effects of volatile organic compounds and new particle formation on real-time hygroscopicity of PM2.5 particles in Seosan, Republic of Korea

The hygroscopicity of PM2.5 particles plays an important role in PM2.5 haze in Northeast Asian countries by influencing particle growth and chemical composition. New particle formation (NPF) and atmospheric volatile organic compounds (VOCs) are factors that influence particle hygroscopicity. However, the lack of real-time hygroscopicity measurements has deterred the understanding of their effects on particle hygroscopicity. In this study, two intensive monitoring campaigns were conducted during the summer of 2021 and spring of 2022 using real-time aerosol instruments, including a humidified tandem differential mobility analyzer (HTDMA), in Seosan, Republic of Korea. The hygroscopicity parameter κ was calculated from the real-time HTDMA measurement data (κGf). The diurnal variations in κGf exhibited strong inverse linear correlations with the total concentration of VOCs (CTVOC) during the two campaigns. The higher atmospheric CTVOC in summer increased the growth rate of the particle diameter from 10 to 40 nm (6 nm/h) compared with that in spring (2.7 nm/h), resulting in a faster change in κGf for 40-nm particles in summer than in spring because of the increase in organic matter in the chemical compositions of particles. In addition, NPF events introduced additional tiny fresh particles into the atmosphere, which reduced the κGf of 40-nm particles and increased the intensity of the less hygroscopic peaks (κGf < 0.1) of κ-probability density functions (κ-PDF) in NPF days. However, 100-nm particles exhibited fewer changes in κGf than 40-nm particles, resulting in additional dominant hygroscopic peaks (κ ∼ 0.2) of κ-PDFs in both NPF and non-NPF days. When κGf values measured in Seosan were compared with those in other Northeast Asian countries in the literature, the κ values for 40-nm particles were lower than those (κ > 0.2) measured in Beijing and Guangzhou, but those for 100-nm particles were close to those measured in the two cities.

Insights into PM2.5 pollution of four small and medium-sized cities in Chinese representative regions: Chemical compositions, sources and health risks

Fine particles (PM2.5) pollution is still a severe issue in some cities in China, where the chemical characteristics of PM2.5 remain unclear due to limited studies there. Herein, we focused on PM2.5 pollution in small and medium-sized cities in key urban agglomerations and conducted a comprehensive study on the PM2.5 chemical characteristics, sources, and health risks. In the autumn and winter of 2019–2020, PM2.5 samples were collected simultaneously in four small and medium-sized cities in four key regions: Dingzhou (Beijing-Tianjin-Hebei region), Weinan (Fenwei Plain region), Fukang (Northern Slope of the Tianshan Mountain region), and Bozhou (Yangtze River Delta region). The results showed that secondary inorganic ions (43.1 %–67.0 %) and organic matter (OM, 8.6 %–36.4 %) were the main components of PM2.5 in all the cities. Specifically, Fukang with the most severe PM2.5 pollution had the highest proportion of SO42− (31.2 %), while the dominant components in other cities were NO3− and OM. The Multilinear Engine 2 (ME2) analysis identified five sources of PM2.5 in these cities. Coal combustion contributed most to PM2.5 in Fukang, but secondary sources in other cities. Combined with chemical characteristics and ME2 analysis, it was preliminarily determined that the primary emission of coal combustion had an important contribution to high SO42− in Fukang. Potential source contribution function (PSCF) analysis results showed that regional transport played an important role in PM2.5 in Dingzhou, Weinan and Bozhou, while PM2.5 in Fukang was mainly affected by short-range transport from surrounding areas. Finally, the health risk assessment indicated Mn was the dominant contributor to the total non-carcinogenic risks and Cr had higher carcinogenic risks in all cities. The findings provide a scientific basis for formulating more effective abatement strategies for PM2.5 pollution.

A comprehensive attribution analysis of PM2.5 in typical industrial cities during the winter of 2016–2018: Effect of meteorology and emission reduction

The frequent occurrence of air pollution in winter has aroused widespread concern. Identifying the detailed source composition of PM2.5 and assessing the reduction effects of different emission sources are crucial steps in improving pollution levels. In this study, we conducted a comprehensive evaluation of emission source reductions, encompassing ten local and ten regional sources. Furthermore, we analyzed the influence of meteorological changes on the abatement of PM2.5 in Tangshan, Shijiazhuang, Xingtai, and Handan during the winter period from 2016 to 2018. Our findings indicate that, in comparison to the winter of 2016, there were significant decreases in the average concentrations of PM2.5 during the winter of 2017. These decreases were attributed to favorable meteorological conditions and emission reductions. However, during the winter of 2018, there was a rebound in PM2.5 concentrations for all four cities. This rebound was primarily caused by adverse meteorological diffusion conditions. Throughout the entire research period spanning from the winter of 2016 to 2018, emission reduction played a significant role in PM2.5 abatement, contributing to 68% in Tangshan, 87% in Shijiazhuang, 93% in Xingtai, and 96% in Handan, respectively. The source apportionment analysis revealed that industrial and residential sources were the dominant contributors to PM2.5 concentrations in the cities. These findings not only confirm the effectiveness of existing industrial and residential pollution control policies but also highlight the imperative need for implementing non-point source control and joint control measures for regional elevated sources in the future.

Quantifying and predicting air quality on different road types in urban environments using mobile monitoring and automated machine learning

Traffic emissions are a primary source of air pollution in urban areas, with air quality being influenced by different types of roads characterized by varying traffic volumes and speeds. Comprehending the distribution of air pollutants and the factors influencing it across different road types holds immense significance in endeavors to enhance air quality within urbanized regions. This study recorded concentrations of PM, SO2, NO2, CO, and O3 on different road types in Shenyang, China, using mobile monitoring. The impacts of road type and microclimatic factors on air quality were quantified using automated machine learning. Among the six road types, the suburban highway exhibited the highest PM, SO2, and NO2 pollution. On the other hand, secondary roads experienced the highest levels of CO and O3 pollution. The automated machine learning models provided accurate predictions for PM2.5, PM10, SO2, NO2, and O3 concentrations (R2 = 0.91, 0.83, 0.82, 0.83, 0.79, respectively). Relative humidity played the most significant role in PM2.5 and PM10 concentrations (55.93% and 59.39%, respectively), followed by air temperature (15.36% and 17.73%) and road types (14.28% and 8.74%). Road types contributed 24.33%, 20.60%, 16.61%, and 11.90% to SO2, CO, O3, and NO2 concentrations, respectively. Overall, this study addresses the limitations of previous research and provides a comprehensive understanding of the impact of road types on air pollutant concentrations in urban environments.

Regional transport of aerosol above boundary layer and its radiation effect trigger severe haze pollution in Beijing

Contribution of the regional transported aerosol above planetary boundary layer (PBL), together with its radiation effect (AR), in triggering severe haze pollution in Beijing were investigated in this work. Both observations and model simulations of a polluted episode during Dec.14–16, 2018 indicated that regional transported aerosol above PBL was downwards transported and resulted in a fast increase in fine particulate matter (diameter < 2.5 μm, PM2.5) at ground level. Quantitative evaluation by sensitive simulations indicated that regional transported aerosol contributed 60.49 μg m−3 (55.1%) in total PM2.5 at ground level, and this contribution became even larger in the beginning stage (e.g., 14:00 on Dec.14) (70.3%). The transported aerosol stabilizes the boundary layer via its AR effect, which further enhances PM2.5 accumulation at ground level. PM2.5 at ground level further increased by 5.07 μg m−3 due to the AR effect of transported aerosol, contributing 77.8% in PM2.5 enhancement due to AR effect. Further analyses indicated that the high altitude of transported aerosol and higher fraction of black carbon in beginning stage were two factors that resulted in transported aerosol exerting more important role in PM2.5 enhancement than local aerosol. Hence, regional transported aerosol and its AR effect trigger rapid increase of PM2.5, exaggerate pollution level in Beijing.

Impact of meteorological conditions and reductions in anthropogenic emissions on PM2.5 concentrations in China from 2016 to 2020

Many efforts have been made to control PM2.5 pollution in China during the National 13th Five-Year Plan and PM2.5 concentrations significantly declined nationwide. Meteorological conditions and pollution emissions play the most important roles in PM2.5 pollution. However, extant quantitative estimations of the contributions of meteorological conditions and anthropogenic emission reductions during the period were mostly based on surface observations data. Using a reanalysis dataset from 2016 to 2020, our results reveal that the annual average PM2.5 concentrations have been reduced yearly in the four key regions: the Beijing-Tianjin-Hebei (BTH) region, Yangtze River Delta (YRD), Pearl River Delta (PRD) and central China. The frequency of stagnation days decreased in 2020 in the YRD and PRD, while it did not show significant fluctuations in the BTH region and central China. Through the sensitivity simulation experiments in 2016 and 2020, the implementation of the emission regulations led to PM2.5 pollution reductions of 6.59 and 5.12 μg m−3, respectively in the BTH region and central China, of which the worsening meteorological conditions offset 61.46% (4.05 μg m−3) and 19.53% (1.00 μg m−3) respectively. However, the impacts of favorable weather conditions and effective anthropogenic restrictions jointly contributed to the improvement in air quality in the YRD and PRD. Anthropogenic controls explained 81.95% (3.75 μg m−3) of the total 4.58 μg m−3 reduction in the YRD and 52.10% (1.86 μg m−3) of the total 3.57 μg m−3 reduction in the PRD. The findings provide a perspective on the causes of pollution events and would help formulate more effective emission reduction policies in the future.

Subchronic exposure to PM2.5 induced renal function damage and intestinal microflora changes in rats

BackgroundExposure to inhalable environmental particulate matter with a diameter of 2.5 µm or smaller (PM2.5) is associated with decreased or impaired kidney function, but the underlying biological mechanisms are not fully understood. Gut microbiota is an emerging key player in the homeostasis regulation of the gut-kidney axis. Few studies have investigated its role in PM2.5 exposure-induced gut-kidney axis homeostasis abnormalities. MethodsIn this study, a versatile aerosol concentration enrichment system for medium- to long-term whole-body exposure was used to expose Sprague-Dawley rats to filtered air (FA) or concentrated ambient PM2.5 for 12 weeks. A correlation analysis of renal impairment and the intestinal microbiome was performed. ResultsThe urine flow rate calculation and renal function analysis showed that PM2.5 exposure significantly impaired renal function and increased the urine flow rate. The fecal microbiota analysis showed that renal impairment and increased urine flow rates were consistent with the reduced estimates of the fecal bacteria Chao1, observed-species, Shannon, and Simpson (richness and diversity indices). Pearson’s correlation analysis showed that the estimated bacterial richness and diversity were correlated with the urine flow rate and renal function. The linear discriminant analysis effect size (LEfSe) analysis revealed differences between animals exposed to PM2.5 and FA in 25 bacterial groups. Further correlation of a single bacterial taxon with the urine flow rate and renal function showed that the relative abundances of 30, 29, 21, and 50 distinct bacterial groups were significantly correlated with the urine flow rate, estimated glomerular filtration rate (eGFR), serum cystatin C (CysC), and beta-2 microglobulin (β2-MG), respectively. ConclusionSubchronic exposure to PM2.5 can cause intestinal ecological disorders, which may, in turn, lead to decreased kidney function or the development of impaired kidney function.

Association of PM2.5 mass and its components with ovarian reserve in a northern peninsular province, China: The critical exposure period and components

BackgroundA possible role of PM2.5 components on ovarian reserve has not been adequately unexplored. ObjectiveTo evaluate the association between PM2.5 components and women’ ovarian reserve over critical exposure periods in northern China, where the level of air pollution is among the nation’s highest. MethodsWe included 15,102 women with serum anti-Müllerian hormone (AMH) measurements from the Center for Reproductive Medicine of Shandong University during 2015–2019. Concentrations of PM2.5 and its five major components (0.1° × 0.1°), including sulfate, nitrate, ammonium, organic matter, and black carbon, were assigned to each residential address. Multivariable linear mixed effect models combined with constituent-residual models were performed to estimate the effect sizes of essential components over six short- to long-term exposure periods. ResultsThe strength of association was stronger during the process from primary to small antral follicle compared with other longer windows. For every interquartile range increase in PM2.5 mass was associated with − 8.7% (95%CI: −12.3%, −4.9%) change in AMH and the effect size was greatest for sulfate. Women with the lower level of attained education and those living inland were more susceptible compared with other population subgroups. ConclusionExposure to specific components of air pollution during critical exposure windows is associated with a decline in ovarian reserve. These data add to the growing body of evidence that environmental factors have adverse effects on reproductive health, particularly for vulnerable population subgroups.

Oxidized and Unsaturated: Key Organic Aerosol Traits Associated with Cellular Reactive Oxygen Species Production in the Southeastern United States.

Exposure to ambient fine particulate matter (PM2.5) is associated with millions of premature deaths annually. Oxidative stress through overproduction of reactive oxygen species (ROS) is a possible mechanism for PM2.5-induced health effects. Organic aerosol (OA) is a dominant component of PM2.5 worldwide, yet its role in PM2.5 toxicity is poorly understood due to its chemical complexity. Here, through integrated cellular ROS measurements and detailed multi-instrument chemical characterization of PM in urban southeastern United States, we show that oxygenated OA (OOA), especially more-oxidized OOA, is the main OA type associated with cellular ROS production. We further reveal that highly unsaturated species containing carbon-oxygen double bonds and aromatic rings in OOA are major contributors to cellular ROS production. These results highlight the key chemical features of ambient OA driving its toxicity. As more-oxidized OOA is ubiquitous and abundant in the atmosphere, this emphasizes the need to understand its sources and chemical processing when formulating effective strategies to mitigate PM2.5 health impacts.

Outdoor air pollution and histologic composition of normal breast tissue

BackgroundBiologic pathways underlying the association between outdoor air pollution and breast cancer risk are poorly understood. Breast tissue composition may reflect cumulative exposure to breast cancer risk factors and has been associated with breast cancer risk among patients with benign breast disease. Herein, we evaluated whether fine particulate matter (PM2.5) was associated with the histologic composition of normal breast tissue. MethodsMachine-learning algorithms were applied to digitized hematoxylin and eosin-stained biopsies of normal breast tissue to quantify the epithelium, stroma, adipose and total tissue area from 3,977 individuals aged 18–75 years from a primarily Midwestern United States population who donated breast tissue samples to the Susan G. Komen Tissue Bank (2009–2019). Annual levels of PM2.5 were assigned to each woman’s residential address based on year of tissue donation. We applied predictive k-means to assign participants to clusters with similar PM2.5 chemical composition and used linear regression to examine the cross-sectional associations between a 5-μg/m3 increase in PM2.5 and square root-transformed proportions of epithelium, stroma, adipose, and epithelium-to-stroma proportion [ESP], overall and by PM2.5 cluster. ResultsHigher residential PM2.5 was associated with lower proportion of breast stromal tissue [β = -0.93, 95% confidence interval: (-1.52, −0.33)], but was not related to the proportion of epithelium [β = -0.11 (-0.34, 0.11)]. Although PM2.5 was not associated with ESP overall [β = 0.24 (-0.16, 0.64)], the association significantly differed by PM2.5 chemical composition (p-interaction = 0.04), with a positive association evident only among an urban, Midwestern cluster with higher concentrations of nitrate (NO3–) and ammonium (NH4+) [β = 0.49 (0.03, 0.95)]. ConclusionsOur findings are consistent with a possible role of PM2.5 in breast cancer etiology and suggest that changes in breast tissue composition may be a potential pathway by which outdoor air pollution impacts breast cancer risk. This study further underscores the importance of considering heterogeneity in PM2.5 composition and its impact on breast carcinogenesis.

Spatial Variation and Relation of Aerosol Optical Depth with LULC and Spectral Indices

In the current study area (Faridabad, Gurugram, Ghaziabad, and Gautam Buddha Nagar), the aerosol concentration is very high, adversely affecting the environmental conditions and air quality. Investigating the impact of Land Use Land Cover (LULC) on Aerosol Optical Depth (AOD) helps us to develop effective solutions for improving air quality. Hence, the spectral indices derived from LULC ((Normalized difference vegetation index (NDVI), Soil adjusted vegetation index (SAVI), Enhanced vegetation index (EVI), and Normalized difference build-up index (NDBI)) with Moderate Resolution Imaging Spectroradiometer (MODIS) Multiangle Implementation of Atmospheric Correction (MAIAC) high spatial resolution (1 km) AOD from the years 2010–2019 (less to high urbanized period) has been correlated. The current study used remote sensing and Geographical Information System (GIS) techniques to examine changes in LULC in the current study region over the ten years (2010–2019) and the relationship between LULC and AOD. A significant increase in built-up areas (12.18%) and grasslands (51.29%) was observed during 2010–2019, while cropland decreased by 4.42%. A positive correlation between NDBI and SAVI (0.35, 0.27) indicates that built-up soils play an important role in accumulating AOD in a semi-arid region. At the same time, a negative correlation between NDVI and EVI (−0.24, −0.15) indicates the removal of aerosols due to an increase in vegetation. The results indicate that SAVI can play an important role in PM2.5 modeling in semi-arid regions. Based on these findings, urban planners can improve land use management, air quality, and urban planning.

Modeling study on the roles of the deposition and transport of PM2.5 in air quality changes over central-eastern China

The role of PM2.5 (particles with aerodynamic diameters ≤ 2.5 µm) deposition in air quality changes over China remains unclear. By using the three-year (2013, 2015, and 2017) simulation results of the WRF/CUACE v1.0 model from a previous work (Zhang et al., 2021), a non-linear relationship between the deposition of PM2.5 and anthropogenic emissions over central-eastern China in cold seasons as well as in different life stages of haze events was unraveled. PM2.5 deposition is spatially distributed differently from PM2.5 concentrations and anthropogenic emissions over China. The North China Plain (NCP) is typically characterized by higher anthropogenic emissions compared to southern China, such as the middle-low reaches of Yangtze River (MLYR), which includes parts of the Yangtze River Delta and the Midwest. However, PM2.5 deposition in the NCP is significantly lower than that in the MLYR region, suggesting that in addition to meteorology and emissions, lower deposition is another important factor in the increase in haze levels. Regional transport of pollution in central-eastern China acts as a moderator of pollution levels in different regions, for example by bringing pollution from the NCP to the MLYR region in cold seasons. It was found that in typical haze events the deposition flux of PM2.5 during the removal stages is substantially higher than that in accumulation stages, with most of the PM2.5 being transported southward and deposited to the MLYR and Sichuan Basin region, corresponding to a latitude range of about 24°N-31°N.

Spatial-Temporal Variation in Health Impact Attributable to PM2.5 and Ozone Pollution in the Beijing Metropolitan Region of China

This study aimed to estimate and compare the spatial-temporal variation in health impact attributable to PM2.5, including the major particulate constituents and anthropogenic emission sectors of PM2.5, and ozone in the Beijing–Tianjin–Hebei (BTH) region using monitoring data from 2013 to 2020. The liquid phase reaction may play an important role in PM2.5 formation in winter. We estimated that 110,613 [(95% CI): 91,913, 128,615] and 9921 (95% CI: 3325, 13,191) cases of all-cause mortality in 2020 were attributable to exposure to PM2.5 and ozone in the BTH region, respectively. The control of PM2.5 pollution is currently a priority over that of ozone. An appropriate co-control policy for PM2.5 and ozone pollution is necessary for the surrounding areas of Beijing City to protect public health. From 2013 to 2020, the mortality owing to exposure to PM2.5 dropped significantly. The reduction in carbonaceous components in PM2.5 can have the most effective health benefits. The top two contributing emission sectors to the mortality from PM2.5 in Beijing were regional transportation and vehicles which could explain approximately 6.5% and 5.1% of the total mortality, respectively. The mortality owing to PM2.5 was higher in Beijing than in Tokyo and Bangkok in East Asia.

Isotopic imprints of aerosol ammonium over the north China plain

Atmospheric PM2.5 poses a variety of health and environmental risks to urban environments. Ammonium is one of the main components of PM2.5, and its role in PM2.5 pollution will likely increase in the coming years as NH3 emissions are still unregulated and rising in many cities worldwide. However, partitioning urban NH4+ sources remains challenging. Although the 15N natural abundance (δ15N) analysis is a promising approach for this purpose, it has seldom been applied across multiple cities within a given region. This limits our understanding of the regional patterns and controls of NH4+ sources in urban environments. Here, we collected PM2.5 samples using an active sampling technique during winter at six cities in the North China Plain to characterize the concentrations, δ15N and sources of NH4+ in PM2.5. We found substantial variations in both the concentrations and δ15N of NH4+ among the sites. The mean NH4+ concentrations across the six cities ranged from 3.6 to 12.1 μg m−3 on polluted days and from 0.9 to 10.6 μg m−3 on non-polluted days. The δ15N ranged from 6.5‰ to 13.9‰ on polluted days and from 8.7‰ to 13.5‰ on non-polluted days. The δ15N decreased with increasing NH4+ concentrations at all six sites. We found that non-agricultural sources (vehicle exhaust, ammonia slip and urban wastes) contributed 72%–94% and 56%–86% of the NH4+ on polluted and non-polluted days, respectively, and that during polluted days, combustion-related emissions (vehicle exhaust and ammonia slip) were positively associated with the proportion of urban area, population density and number of vehicles, highlighting the importance of local sources of particulate pollution. This study suggests that the analysis of 15N in aerosol NH4+ is a promising approach for apportioning atmospheric NH3 sources over a large region, and this approach has potential for mapping rapidly and precisely the sources of NH3 emissions.

The "Pollution Halo" Effect of FDI: Evidence from the Chinese Sichuan-Chongqing Urban Agglomeration.

In this paper, panel data from nineteen key cities in the Sichuan–Chongqing urban agglomeration from 2003 to 2016 were used as the study sample. Using the stochastic impacts by regression on population, affluence, and technology (STIRPAT) model, the effect of foreign direct investment (FDI) on particulate matter (PM2.5) pollution and its action mechanism in the Sichuan–Chongqing urban agglomeration were considered for both socioeconomic and natural factors. The results showed that the “pollution halo” hypothesis of FDI in the Sichuan–Chongqing urban agglomeration has been supported. There are significant positive spatial spillover effects of PM2.5 pollution in this urban agglomeration, and the introduction of FDI is conducive to alleviating PM2.5 pollution in the urban agglomeration. Similar to the “inverted U” curve proposed by the environmental Kuznets curve (EKC) hypothesis, there was a significant “inverted U” curve relationship between PM2.5 pollution and economic growth in the Sichuan–Chongqing urban agglomeration. However, there was a significant “U”-type curve relationship between the urbanization degree and the PM2.5 concentration, which indicates that the current urbanization mode may aggravate the pollution degree of PM2.5 in the urban agglomeration in the long term. Furthermore, the two natural factors of annual average temperature and annual precipitation play an important role in PM2.5 pollution and spatial spillover effect in the Sichuan–Chongqing urban agglomeration. Economic development and rationalization of the industrial structure are the main ways by which FDI affects PM2.5 pollution in the urban agglomeration. The research conclusions of this study can be of great practical significance to optimize the regional industrial layout, control PM2.5 pollution, and establish a sustainable development policy system in the Sichuan–Chongqing urban agglomeration.