Toxicological responses of A549 and HCE-T cells exposed to fine particulate matter at the air-liquid interface.

Fine particulate matter (PM2.5) can enter the human body in various ways and have adverse effects on human health. Human lungs and eyes are exposed to the air for a long time and are the first to be exposed to PM2.5. The "liquid immersion exposure method" has some limitations that prevent it from fully reflecting the toxic effects of particulate matter on the human body. In this study, the collected PM2.5 samples were chemically analyzed. An air-liquid interface (ALI) model with a high correlation to the in vivo environment was established based on human lung epithelial cells (A549) and immortalized human corneal epithelial cells (HCE-T). The VITROCELL Cloud 12 system was used to distribute PM2.5 on the cells evenly. After exposure for 6 h and 24 h, cell viability, apoptosis rate, reactive oxygen species (ROS) level, expression of inflammatory factors, and deoxyribonucleic acid (DNA) damage were measured. The results demonstrated significant dose- and time-dependent effects of PM2.5 on cell viability, cell apoptosis, ROS generation, and DNA damage at the ALI, while the inflammatory factors showed dose-dependent effects only. It should be noted that even short exposure to low doses of PM2.5 can cause cell DNA double-strand breaks and increased expression of γ-H2AX, indicating significant genotoxicity of PM2.5. Increased abundance of ROS in cells plays a crucial role in the cytotoxicity induced by PM2.5 exposure These findings emphasize the significant cellular damage and genotoxicity that may result from short-term exposure to low levels of PM2.5.

Acute exposure to seasonal PM2.5 induces toxicological responses in A549 cells cultured at the air-liquid interface mediated by oxidative stress and endoplasmic reticulum stress.

Atmospheric fine particulate matter (PM2.5) enters the human body through respiration and poses a threat to human health. This is not only dependent on its mass concentration in the atmosphere, but also related to seasonal variations in its chemical components, which makes it important to study the cytotoxicity of PM2.5 in different seasons. Traditional immersion exposure cannot simulate the living environment of human epithelial cells in the human body, making this method unsuitable for evaluating the inhalation toxicity of PM2.5. In this study, a novel air-liquid interface (ALI) particulate matter exposure device (VITROCELL Cloud 12 system) was used to evaluate the toxic effects and potential mechanisms of human lung epithelial cells (A549) after exposure to seasonal PM2.5. PM2.5 samples from four seasons were collected and analyzed for chemical components. After 6 h of exposure to seasonal PM2.5, winter PM2.5 exhibited the highest cytotoxicity among most toxicity indicators, especially apoptosis rate, reactive oxygen species (ROS), inflammatory responses and DNA damage (γ-H2AX). The effect of autumn PM2.5 on apoptosis rate was significantly higher than that in spring, and there was no significant difference in other toxicity indicators between spring and autumn. The cytotoxicity of summer PM2.5 was the lowest among the four seasons. It should be noted that even exposure to low doses of summer PM2.5 leads to significant DNA damage in A459 cells. Correlation analysis results showed that water-soluble ions, metallic elements, and polycyclic aromatic hydrocarbons (PAHs) were associated with most toxicological endpoints. Inhibitors of oxidative stress and endoplasmic reticulum (ER) stress significantly inhibited cellular damage, indicating that PM2.5-induced cytotoxicity may be related to the generation of ROS and ER stress. In addition, PM2.5 can induce ER stress through oxidative stress, which ultimately leads to apoptosis.

Chemical Characteristics and Cytotoxicity to GC-2spd(ts) Cells of PM2.5 in Nanjing Jiangbei New Area from 2015 to 2019.

PM2.5 is an air pollutant with complex components. After entering the body through respiration, PM2.5 can not only cause respiratory diseases, but also break through the blood-testis barrier and influence the reproductive system. PM2.5 with different components may result in different toxic effects. In the first five years of Nanjing Jiangbei New Area, industrial transformation would change the concentration and chemical fraction of PM2.5 in the local environment to a certain extent. In this study, PM2.5 collected in Nanjing Jiangbei New Area every autumn and winter from 2015 to 2019 was analyzed. PM2.5 concentration generally decreased year by year. The large proportion of secondary inorganic ions indicated the presence of secondary pollution at the sampling site. PM2.5 was mainly emitted from fossil fuel combustion and vehicle exhaust. The cytotoxicity of PM2.5 samples was evaluated by PM2.5 exposure to mouse spermatocytes (GC-2spd(ts) cells). Cell viability was relatively low in 2016 and 2018, and relatively high in 2017 and 2019. Reactive oxygen species levels and DNA damage levels followed similar trends, with an overall annual decrease. The cytotoxicity of PM2.5 on GC-2spd(ts) cells was significantly correlated with water-soluble ions, water-soluble organic carbon, heavy metals and polycyclic aromatic hydrocarbons (p < 0.01). According to principal component analysis and multiple linear regression, fossil fuel combustion, secondary transformation of pollutants and construction dust were identified as the major contributors to cytotoxic effects, contributing more than 50%.

Chemical Composition and Transgenerational Effects on Caenorhabditis elegans of Seasonal Fine Particulate Matter.

While numerous studies have demonstrated the adverse effects of fine particulate matter (PM) on human health, little attention has been paid to its impact on offspring health. The multigenerational toxic effects on Caenorhabditis elegans (C. elegans) were investigated by acute exposure. PM2.5 and PM1 samples were collected and analysed for their chemical composition (inorganic ions, metals, OM, PAHs) in different seasons from April 2019 to January 2020 in Lin'an, China. A higher proportion of organic carbon components (34.3%, 35.9%) and PAHs (0.0144%, 0.0200%) occupied the PM2.5 and PM1 samples in winter, respectively. PM1 in summer was enriched with some metal elements (2.7%). Exposure to fine PM caused developmental slowing and increased germ cell apoptosis, as well as inducing intestinal autofluorescence and reactive oxygen species (ROS) production. PM1 caused stronger toxic effects than PM2.5. The correlation between PM component and F0 generation toxicity index was analysed. Body length, germ cell apoptosis and intestinal autofluorescence were all highly correlated with Cu, As, Pb, OC and PAHs, most strongly with PAHs. The highest correlation coefficients between ROS and each component are SO42- (R = 0.743), Cd (R = 0.816) and OC (R = 0.716). The results imply that OC, PAHs and some transition metals play an important role in the toxicity of fine PM to C. elegans, where the organic fraction may be the key toxicogenic component. The multigenerational studies show that PM toxicity can be passed from parent to offspring, and gradually returns to control levels in the F3-F4 generation with germ cell apoptosis being restored in the F4 generation. Therefore, the adverse effects of PM on reproductive damage are more profound.

Ecotoxicity induced by total, water soluble and insoluble components of atmospheric fine particulate matter exposure in Caenorhabditis elegans.

Although PM2.5 could cause toxicity in environmental organisms, the toxicity difference of PM2.5 under different solubilities is still poorly understood. To acquire a better knowledge of the ecotoxicity of PM2.5 under different solubilities, the model animal Caenorhabditis elegans (C. elegans) was exposed to Total-PM2.5, water insoluble components of PM2.5 (WIS-PM2.5) and water soluble components of PM2.5 (WS-PM2.5). The physiological (growth, locomotion behavior, and reproduction), biochemical (germline apoptosis, and reactive oxygen species (ROS) production) indices, and the related gene expression were examined. According to the findings, acute exposure to these three components caused adverse physiological effects on growth and locomotion behavior, and significantly induced germline apoptosis or ROS production. In contrast, prolonged exposure showed stronger adverse effects than acute exposure. Additionally, the results of multiple toxicological endpoints showed that the toxicity effects of WIS-PM2.5 are more intense than WS-PM2.5, which means that insoluble components contributed more to the toxicity of PM2.5. Prolonged exposure to 1000 mg/L WS-PM2.5, WIS-PM2.5, and Total-PM2.5 dramatically altered the expression of stress-related genes, which further indicated that apoptosis, DNA damage and oxidative stress play a crucial part in toxicity induced by PM2.5.

The Cytotoxic Effects of Fine Particulate Matter (PM2.5) from Different Sources at the Air-Liquid Interface Exposure on A549 Cells.

The health of humans has been negatively impacted by PM2.5 exposure, but the chemical composition and toxicity of PM2.5 might vary depending on its source. To investigate the toxic effects of particulate matter from different sources on lung epithelial cells (A549), PM2.5 samples were collected from residential, industrial, and transportation areas in Nanjing, China. The chemical composition of PM2.5 was analyzed, and toxicological experiments were conducted. The A549 cells were exposed using an air-liquid interface (ALI) exposure system, and the cytotoxic indicators of the cells were detected. The research results indicated that acute exposure to different sources of particulate matter at the air-liquid interface caused damage to the cells, induced the production of ROS, caused apoptosis, inflammatory damage, and DNA damage, with a dose-effect relationship. The content of heavy metals and PAHs in PM2.5 from the traffic source was relatively high, and the toxic effect of the traffic-source samples on the cells was higher than that of the industrial- and residential-source samples. The cytotoxicity of particulate matter was mostly associated with water-soluble ions, carbon components, heavy metals, PAHs, and endotoxin, based on the analysis of the Pearson correlation. Oxidative stress played an important role in PM2.5-induced biological toxicity.

Reproductive toxicity and underlying mechanisms of fine particulate matter (PM2.5) on Caenorhabditis elegans in different seasons.

Although numerous studies have investigated that atmospheric fine particulate matter (PM2.5) can be toxic to environmental organisms, the research on the reproductive toxicity of PM2.5 is limited, and the key toxic components and underlying mechanisms remain unknown. In this work, PM2.5 samples of four seasons in Nanjing from March 1, 2021, to February 28, 2022 were collected and the chemical components were analyzed. Caenorhabditis elegans (C. elegans) was employed to conduct the toxicological testing. The reproductive toxicity of PM2.5 to C. elegans in different seasons was evaluated by multiple reproductive endpoints. Exposure to high concentrations of PM2.5 significantly decreased the brood size and the number of fertilized eggs in utero. PM2.5 exposure also increased the number of germ cell corpses and caused abnormal expression of apoptosis-related genes (ced-9, ced-4, and ced-3), which confirmed that PM2.5 induced germline apoptosis. In addition, PM2.5 exposure significantly increased the production of reactive oxygen species (ROS) in C. elegans and the fluorescence intensity of HUS-1 protein in of transgenic strain WS1433. Meanwhile, the expression of genes related to DNA damage (cep-1, clk-2, egl-1, and hus-1) and oxidative stress (mev-1, isp-1, and gas-1) also significantly altered in C. elegans, suggesting induction of DNA damage and oxidative stress. According to Pearson correlation analyses, DNA damage and oxidative stress were significantly correlated with multiple reproductive endpoints in C. elegans. Thus, it was speculated that PM2.5 caused reproductive dysfunction and germ cell apoptosis in C. elegans may be by inducing ROS and DNA damage. In addition, heavy metals in PM2.5 were significantly correlated with multiple endpoints at physiological and biochemical, suggesting that the heavy metals might be an important contributor to the reproductive toxicity induced by PM2.5.

Mechanical Property Test of Grass Carp Skin Material Based on the Digital Image Correlation Method.

Fish is a common and widely distributed creature. Its skin has a unique physiological structure and plays an important role in many fields. Fish skin also has important potential value for bionics research. This study aims to provide a method and a reliable data for the study of bionics. A method of measuring the mechanical properties of fish skin samples using a binocular stereo digital image correlation (DIC) system combined with a synchronous tensile testing machine was proposed. The mechanical properties (e.g., elastic modulus E and strain) of grass fish skin samples (GFSA) were tested in hydrophilic and dry states. A dual-frequency laser interferometer was used to calibrate the tensile testing machine synchronously, and the feasibility and strain accuracy of DIC in GFSA measurement were verified by finite element method (FEM). The results show differences in the mechanical properties of GFSA between different individuals, different parts, and different states. Under the same stress, the head was easy to deform, and the strain was the largest, and E was the smallest. The tail result was the opposite of the head result.

Experimental analysis of high-temperature creep in FV566 steel based on digital image correlation.

Digital image correlation (DIC) is an optical measurement method of material strain/displacement based on visible light illumination, which can be used for the measurement of long-term mechanical behavior. In this paper, an experimental method for analyzing high-temperature creep in FV566 steel material based on DIC was independently designed. Aiming at the problems of glass observation window medium refraction and thermal airflow disturbance in high-temperature testing, the corresponding correction methods were proposed to improve the measurement accuracy. Based on the above methods, high-temperature creep tests were carried out on three specimens with different shapes, and the strain concentration area at 600°C was calculated. Then, the influences of shape and other properties on material creep failure, stress distribution, and actual strain were investigated. Finally, the DIC calculation results were analyzed and compared with results of finite element analysis and the final fracture position of the specimen. The three results had a high degree of consistency, which verified that the proposed method can accurately measure and analyze the creep behavior of materials.

Enhancing the Low-Temperature CO Oxidation over CuO-Based α-MnO2 Nanowire Catalysts.

A series of CuO-based catalysts supported on the α-MnO2 nanowire were facilely synthesized and employed as the CO oxidation catalysts. The achieved catalysts were systematically characterized by XRD, SEM, EDS-mapping, XPS and H2-TPR. The catalytic performances toward CO oxidation had been carefully evaluated over these CuO-based catalysts. The effects of different loading methods, calcination temperatures and CuO loading on the low temperature catalytic activity of the catalyst were investigated and compared with the traditional commercial MnO2 catalyst with a block structure. It was found that the slenderness ratio of a CuO/α-MnO2 nanowire catalyst decreases with the increase in CuO loading capacity. The results showed that when CuO loading was 3 wt%, calcination temperature was 200 °C and the catalyst that was supported by the deposition precipitation method had the highest catalytic activity. Besides, the α-MnO2 nanowire-supported catalysts with excellent redox properties displayed much better catalytic performances than the commercial MnO2-supported catalyst. In conclusion, the CuO-based catalysts that are supported by α-MnO2 nanowires are considered as a series of promising CO oxidation catalysts.

Identification and semi-quantification of nitrooxy organosulfates in aerosol particles by HPLC-MS/MS.

Organosulfates (OSs) derived from the oxidation of biogenic volatile organic compounds (BVOCs) in the presence of anthropogenic sulfate aerosols are the important tracers of secondary organic aerosols (SOAs). In order to better understand the concentration of pinene-nitrooxy organosulfates (pNOSs) in Nanjing, a sensitive high-performance liquid chromatography-electron spray ionization spectrum/mass spectrum (HPLC-ESI-MS/MS) to determine pNOSs in PM2.5 has been developed and validated in this study. Firstly, Hypersil Gold C18 (Thermo Scientific, San Jose, USA) was selected to separate pinene-derived nitrooxy organosulfates (pNOSs) based on their polarity. Three kinds of pNOSs were detected in the full scan mode (MS) with an ESI source under the negative mode. Secondly, three isomers of pNOSs with fragment ions m/z 220, 151, and 142 were identified based on the MS/MS maps. At least two pairs of transfer ions should be selected as identification and quantification ions according to the optimization results of target compounds. For example, to determine pNOSs, these transfer ions of m/z 294 → 247, m/z 294 → 231, m/z 294 → 220, m/z 294 → 142, m/z 294 → 151, m/z 294 → 96, m/z 294 → 80 were selected as quantification and identification ions. Finally, the influence of scan mode on pNOS detection was evaluated, and the results showed that pNOSs were most sensitive in the SRM (selected reaction monitor) scan mode. Therefore, the SRM scan mode was chosen to detect pNOSs. We applied this method to analyze year-round PM2.5 (PM2.5 is fine particulate matter, which refers to particulate matter in ambient air with an aerodynamic equivalent diameter of less than or equal to 2.5 microns) samples in Nanjing. The average concentration of all the three kinds of pNOSs was 69.95 ng m-3. The results showed that the average concentration of pNOSs was high in spring (92.94 ng m-3) and summer (90.57 ng m-3), and lowest in winter (30.03 ng m-3).

Seasonal variation, source contribution, and impact factors of biogenic organic aerosols in PM2.5 in Nanjing, China.

In this study, a liquid chromatography-mass spectrometry (HPLC-ESI-MS/MS) was used to develop a rapid method to detect carbohydrates (one anhydrosugar, five sugars, and four sugar alcohols) and monoterpene secondary organic aerosol (SOAM) tracers in the atmosphere, successfully applied to 139 atmospheric aerosol samples in Nanjing in 2019. Anhydrosugar (levoglucosan) is the most abundant carbohydrate in the atmospheric environment, with an annual mean concentration of 103.96 ng m-3. The measured compounds exhibited distinct seasonal variation, with a higher concentration in spring and summer and a lower concentration in autumn and winter. The distinct seasonal variation in these Bioorganic aerosol (BOA) tracers may be caused by the different dominant sources in different seasons. Their seasonal trends are also similar to other worldwide observations. In Nanjing, the yield of SOAM tracers is affected by meteorological conditions and anthropogenic pollutants (e.g., NO2 and O3). Furthermore, five source factors (secondary formation, biomass burning, soil resuspension, plant debris, and fungal spores) of BOA and their geographic origin were obtained using the Positive Matrix Factor (PMF) and Potential Source Contribution Factor (PSCF) models. The contribution of these factors to BOA also varies, with biomass burning (77.4 %) contributing the most, followed by fungal spores (12.2 %) and soil suspension (2.1 %).

Seasonal variations and potential sources of biomass burning tracers in particulate matter in Nanjing aerosols during 2017-2018.

Biomass burning (BB) is an important source of atmospheric particulate matter and can adversely affect air quality, visibility, human health, and climate change. To study the characteristics and potential source regions of BB tracers in PM2.5, a liquid chromatography-mass spectrometry instrument (HPLC-MS/MS) is applied in this study to develop and validate a method to determine organic tracers of BB in 397 aerosol samples. The total mean concentrations of 17 tracers measured in 2017 and 2018 were 333.32 ng m-3 and 243.45 ng m-3, respectively. Among them, the concentration of levoglucosan was the highest among all the tracers, with 325.63 ng m-3 in 2017 and 237.47 ng m-3 in 2018. The BB tracers showed obvious seasonal variations characteristics, most of which were abundant in winter. However, the concentrations of 3,4-dimethoxyacetic acid and sinapinic acid were higher in summer and spring than that in the other seasons. There were obvious differences in the Potential Source Contribution Factor (PSCF) model results of the BB's potential source area annually and in different seasons. The results of the potential source analysis showed that Beijing-Tianjin-Hebei had a great impact on the Nanjing air quality in 2017. Finally, five source factors for BB were identified based on the Positive Matrix Factor (PMF) model, and these were cellulose, hardwood, softwood, grass, and secondary formed. During the 2 years, cellulose was the largest contributor to biomass burning. Owing to the different fire conditions each year, the contribution of the five factors to the BB tracers was also different. For example, the contribution of softwood to the BB tracers was greater in 2018 (8.4%) than in 2017 (5.2%), while the contributions of hardwood and cellulose did not change significantly.

Universal calibration for a ring camera array based on a rotational target.

Panoramic dynamic and static measurements of objects in the application of vision measurement are difficult due to the constraints of a camera field of view and multicamera calibration technology. This paper proposes a universal global calibration method for ring multicamera systems based on rotating target and multi-view vision technology. This method uses a rotating target to establish the relationship between ring multi-camera arrays, retrieves the coordinates of the target corners from the fields of view of different cameras, and combines them with the rotation angle to complete the coordinate unification of the system. The unification of coordinates is unaffected by the overlapping fields of view between cameras, and the number of cameras can be configured arbitrarily. The calibration accuracy, validity, and precision of the proposed method are verified through reprojection error, dynamic tensile test, and 3D reconstruction.

Binocular DIC system for 3D correlation measurements.

A novel, to the best of our knowledge, mirror-assisted binocular stereo digital image correlation (DIC) system is proposed for the reconstruction of the overall contour, thickness, and strain measurement of the object. First, the angle between the two plane mirrors is adjusted until two virtual images and two real images can be formed in the mirrors. Then, the adjustable speckle size and definition characteristics of the projection speckle technology are fully utilized to realize the precise measurement of the mirror plane. Finally, a 3D contour reconstruction experiment and a dynamic stretching experiment are conducted to verify the proposed method. Experimental results show that the proposed method can achieve a 360° omnidirectional deformation measurement, and the 3D reconstruction of the object with complex contours has a relatively ideal reconstruction effect. According to the virtual image, the thickness of the conventional specimen can be completed easily, and the coordinates of the front and rear surfaces need not be subtracted. The dynamic strain can be calculated separately from the front and rear surfaces of the standard specimen and can be realized in the dynamic tensile experiment. Compared with the existing binocular DIC system, the proposed method can provide more valid data with guaranteed excellent results. It provides a better implementation method for omnidirectional measurement, thickness, and stress-strain calculation of the object.

The Relative Contributions of Different Chemical Components to the Oxidative Potential of Ambient Fine Particles in Nanjing Area.

Ambient fine particles (PM2.5) have been shown to have adverse health effects by inducing oxidative stress. Here, dithiothreitol (DTT)-based oxidative potential (OP) was used to assess the capacity of oxidative stress caused by PM2.5. In this study, PM2.5 samples were collected in the Nanjing area in 2016, and physicochemical properties and DTT activity were investigated. The annual mean PM2.5 mass concentration was 73 µg m-3 and greatly varied among seasons (spring > winter > summer > autumn). Three fluorescent substances were identified by the excitation-emission matrix (EEM) spectrum. The annual mean mass-normalized DTT activity (DTTm; 0.02 nmol min-1 µg-1) was similar to that documented for cities of some developed countries. The annual mean volume-normalized DTT activity (DTTv) showed a relatively high value of 1.16 nmol min-1 m-3, and the seasonal mean DTTv was highest in winter, followed by spring, autumn, and summer, whose pattern is different from PM2.5 mass concentration. Correlation and multiple linear regression analysis suggested that transition metals may have a greater effect on OP in autumn and winter, humic-like substances and UV absorbing aromatic substances may have a strong effect on OP in spring and summer. Generally, this study enhances our understanding of seasonal variation in health effects associated with PM2.5.

Changes of air quality and its associated health and economic burden in 31 provincial capital cities in China during COVID-19 pandemic.

With outbreak of the novel coronavirus disease (COVID-19), immediate prevention and control actions were imposed in China. Here, we conducted a timely investigation on the changes of air quality, associated health burden and economic loss during the COVID-19 pandemic (January 1 to May 2, 2020). We found an overall improvement of air quality by analyzing data from 31 provincial cities, due to varying degrees of NO2, PM2.5, PM10 and CO reductions outweighing the significant O3 increase. Such improvement corresponds to a total avoided premature mortality of 9410 (7273-11,144) in the 31 cities by comparing the health burdens between 2019 and 2020. NO2 reduction was the largest contributor (55%) to this health benefit, far exceeding PM2.5 (10.9%) and PM10 (23.9%). O3 instead was the only negative factor among six pollutants. The period with the largest daily avoided deaths was rather not the period with strict lockdown but that during February 25 to March 31, due to largest reduction of NO2 and smallest increase of O3. Southwest, Central and East China were regions with relatively high daily avoided deaths, while for some cities in Northeast China, the air pollution was even worse, therefore could cause more deaths than 2019. Correspondingly, the avoided health economic loss attributable to air quality improvement was 19.4 (15.0-23.0) billion. Its distribution was generally similar to results of health burden, except that due to regional differences in willingness to pay to reduce risks of premature deaths, East China became the region with largest daily avoided economic loss. Our results here quantitatively assess the effects of short-term control measures on changes of air quality as well as its associated health and economic burden, and such information is beneficial to future air pollution control.

Chemical characteristics, sources and evolution processes of fine particles in Lin'an, Yangtze River Delta, China.

In this study, daily PM2.5 mass and chemical composition were measure in Lin'an Reginal Background Station, Yangzte River Delta, from March 1, 2018, to February 28, 2019. Organic matter (OM) was found to be the most dominant component in four seasons. The proportions of nitrate in PM2.5 presented dramatically lowest in warm seasons but highest in winter, indicating that NO3- was maily driven by thermodynamics. Regional transportation in winter plays a strong impact on PM2.5 concentration, which showed the highest average mass of 60.1 µg m-3. Sulfate occupied a significant portion of PM2.5 in summer (19%), followed by spring (17%), fall (15%), and winter (12%), respectively, suggesting photochemical processes may play a dominant role in the sulfate formation. Secondary inorganic aerosol (SIA) was the dominant component (70%) in the highest polluted periods (PM2.5 > 75 µg m-3), whereas OM decreased into the lowest fraction (22%) of PM2.5. Nitrate was the most important component in SIA in the highest polluted periods with regarding winter. Source apportionment results shown that winter haze was likely strongly dominated by SIA, which was mainly affected by air masses from the North China Plain and Shang-Hangzhou direction. PM2.5 is known to play an important role in sunlight absorption and reversing to human health, continuous observation on PM2.5 species in a background site can help us to evaluate the control policy, and promote our insights to lifetime, formation pathways, health effects of PM2.5.

Characterization of Fine Particulate Matter and Associated Health Burden in Nanjing.

Particulate matter (PM) air pollution has become a serious environmental problem in Nanjing and poses great health risks to local residents. In this study, characteristics of particulate matter with an aerodynamic diameter less than 2.5 µm (PM2.5) over Nanjing were analyzed using hourly and daily averaged PM2.5 concentrations and meteorological parameters collected from nine national monitoring sites during the period of March 2014 to February 2017. Then, the integrated exposure-response (IER) model was applied to assess premature mortality, years of life lost (YLL) attributable to PM2.5, and mortality benefits due to PM2.5 reductions. The concentrations of PM2.5 varied among hours, seasons and years, which can be explained by differences in emission sources, secondary formations and meteorological conditions. The decreased ratio of PM2.5 to CO suggested that secondary contributions decreased while the relative contributions of vehicle exhaust increased from increased CO data. According to the values of attributable fractions (AF), stroke was the major cause of death, followed by ischemic heart disease (IHD), lung cancer (LC) and chronic obstructive pulmonary disease (COPD). The estimated total deaths in Nanjing due to PM2.5 were 12,055 and 10,771, leading to 98,802 and 87,647 years of life lost in 2014 and 2015, respectively. The elderly and males had higher health risks than youngsters and females. When the PM2.5 concentrations meet the World Health Organization (WHO) Air Quality Guidelines (AQG) of 10 µg/m³, 84% of the premature deaths would be avoided, indicating that the Nanjing government needs to adopt more stringent measure to reduce PM pollution and enhance the health benefits.