Fine Particulate Matter Constituents Research Articles

Fine Particulate Matter Constituents and Infant Mortality in Africa: A Multi-Country Study

Background: Few studies have investigated the association between exposure to fine particulate matter (PM2.5) and infant mortality in developing countries, especially for the health effects of specific PM2.5 constituents. We aimed to examine the association of long-term exposure to specific PM2.5 constituents with infant mortality in 15 African countries from 2005 to 2015. Methods: Based on the Demographic and Health Surveys (DHS) dataset, we included birth history records from 15 countries in Africa and conducted a multi-country cross-sectional study to examine the associations between specific PM2.5 constituents and infant mortality. We used satellite-based models to predict annual residential exposure to PM2.5 and its six constituents, including organic carbon (OC), black carbon (BC), sulfate (SO>sub>42−) , nitrate (NO3−), ammonium (NH4+), and soil dust (DUST). Multivariable logistic regression analysis was employed by fitting single-constituent models, the constituent-PM2.5 models, and the constituent-residual models. We also conducted stratified analyses by potential effect modifiers and examined the specific associations for each country. Findings: We found positive and significant associations between PM2.5 total mass and most of its constituents with infant mortality. In the single-constituent model, for an IQR increase in pollutant concentrations, the odds ratio (OR) of infant mortality was 1·03 (95%CI; 1·01, 1·06) for PM2.5 total mass, and was 1·04 (95%CI: 1·02, 1·06), 1·04 (95%CI: 1·02, 1·05), 1·02 (95%CI: 1·00, 1·03), 1·04 (1·01, 1·06) for BC, OC, SO42-, and DUST, respectively. The associations of BC, OC, and SO42- remained significant in the other two models. We observed larger estimates in subgroups with older maternal age, living in urban areas, using unclean cooking energy, and with access to piped water. The associations varied among countries, and by different constituents. Interpretation: The carbonaceous fractions and sulfate play a major important role among PM2.5 constituents on infant mortality, suggesting the need for a targeted controlling strategy on corresponding sources of emissions. Funding: HK was supported by the National Natural Science Foundation of China (92043301 and 82030103). CL was supported by the China Postdoctoral Science Foundation (2020M681185) and China National Postdoctoral Program for Innovative Talents (BX20200088). Declaration of Interests: The authors have declared that no competing interests exist.

Acute effects of fine particulate matter constituents on cardiopulmonary function in a panel of COPD patients

BackgroundExposure to fine particulate matter (PM2.5) has been linked with adverse cardiorespiratory health conditions. However, evidence for PM2.5 constituents is still scarce, especially among patients with chronic obstructive pulmonary disease (COPD). ObjectiveTo investigate the associations of short-term exposure to different chemical constituents of PM2.5 with measures of cardiac and lung function in COPD patients. MethodsWe conducted a retrospective panel study among 100 COPD patients who received repeated measures of left ventricular ejection fraction (LVEF), forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and peak expiratory flow (PEF) in Shanghai, China from August 2014 to September 2019. Daily PM2.5 and PM2.5 constituents were obtained from fixed-site monitoring station. Linear mixed-effects models were used to estimate the associations of PM2.5. ResultsWe found water-soluble ions of PM2.5, mainly NO3−, SO42−, and NH4+ were robustly associated with reduced LVEF, and the reductions in LVEF associated with an IQR increase of them ranged from 1.8% to 2.0% (lag 1 d). Metal constituents such as Cu and As were associated with FEV1, FVC and PEF. The corresponding reductions in lung function parameters for an IQR increase of them ranged from 1.4% to 2.3% (lag 0 or 1 d). These associations remained relatively robust after adjusting for total PM2.5 mass and gaseous pollutants. ConclusionsOur results suggest that water-soluble ions and several metal/metalloid elements might be important constituents in PM2.5 that were associated with reduced cardiorespiratory function among COPD patients.

Depression and Anxiety Associated with Exposure to Fine Particulate Matter Constituents: A Cross-Sectional Study in North China.

The association between fine particulate matter (PM2.5) exposure and mental disorders is attracting increasing attention, but the roles of specific PM2.5 chemical constituents have yet to be explored. We conducted a multicenter cross-sectional study in nine cities located in the Beijing-Tianjin-Hebei region in China to assess the effects of PM2.5 and chemical constituents on depression and anxiety. The Patient Health Questionnaire-9 (PHQ-9) and Generalized Anxiety Disorder (GAD-7) scale were used to quantify the depression and anxiety status, atmospheric monitoring data from fixed stations was used to calculate exposure concentrations. We performed multiple logistic regression models to assess the associations of PM2.5 chemical constituents exposure over the preceding 2 weeks with depression and anxiety. Overall, anxiety and depression were significantly associated with organic carbon (OC), elemental carbon (EC), copper (Cu), cadmium (Cd), nickel (Ni), and zinc (Zn). Subgroup analysis showed a stronger effect of PM2.5 constituents on depression during the heating period. This study provide evidence for the possible link between PM2.5 constituents and mental disorders among middle-aged and elderly Chinese adults, which requires further validation of the causal correlation. Our findings support the need for a stricter regulation on emissions of certain specific constituents, in addition to targeting control of total PM2.5 emission concentration.

Fine particulate matter constituents and sub-clinical outcomes of cardiovascular diseases: A multi-center study in China

BackgroundLimited evidence is available on the associations of long-term exposure to various fine particulate matter (PM2.5) constituents with sub-clinical outcomes of cardiovascular disease (CVD) in China. ObjectivesWe aimed to explore the associations of PM2.5 and its constituents with blood pressure (BP), fasting glucose, and cardiac electrophysiological (ECG) properties based on a national survey of 5852 Chinese adults, who participated in the Sub-Clinical Outcome of Polluted Air study, from July 2017 to March 2019. MethodsAnnual residential exposure to PM2.5 and its constituents of each subject was predicted by a satellite-based mode. We assessed the associations between five main constituents [organic matter (OM), black carbon (BC), sulfate (SO42−), nitrate (NO3−), ammonium (NH4+)] of PM2.5 and systolic BP (SBP), diastolic BP (DBP), fasting glucose, and ECG measurements (PR, QRS, QT, and QTc interval) using multivariable linear regression models. ResultsLong-term PM2.5 exposure was significantly associated with increased levels of fasting glucose, DBP, and ECG measurements. An IQR increase in OM (8.2 μg/m3) showed considerably stronger associations with an elevated fasting glucose of 0.39 mmol/L (95%CI confidence interval: 0.28, 0.49) compared with other PM2.5 constituents. Meanwhile, an IQR increase in NO3−, NH4+ and OM had stronger associations with DBP and ECG parameters compared with BC and SO42−. ConclusionsThis nationwide multi-center study in China indicated that some constituents (i.e., OM, NO3−, and NH4+) might be mainly responsible for the association of PM2.5 with sub-clinical outcomes of CVD including BP, fasting glucose, and ECG measurements.

Fine particulate matter constituents and heart rate variability: A panel study in Shanghai, China

BackgroundShort-term exposure to fine particulate matter (PM2.5) has been associated with reduced heart rate variability (HRV), an established indicator of cardiac autonomic function, but it remains uncertain which specific constituents of PM2.5 had key impacts. ObjectiveTo examine the short-term associations between various PM2.5 constituents and HRV measures. MethodsWe conducted a retrospective panel study among 78 participants who received repeated 24-h electrocardiogram testing in Shanghai, China from 2015 to 2019. We obtained daily concentrations of 14 main chemical constituents of PM2.5 from a fixed-site monitor. During 3 or 4 rounds of follow-ups, we measured 6 HRV parameters, including 3 frequency-domain parameters (power in very low frequency, low frequency and high frequency) and 3 time-domain parameters (standard deviation of normal-to-normal intervals, root mean square successive difference and percent of adjacent normal R-R intervals with a difference ≥50 msec). We used linear mixed-effects models to analyze the data after controlling for time trends, environmental and individual risk factors. ResultsThe average daily PM2.5 exposure was 45.8 μg/m3 during the study period. The present-day exposure to PM2.5 had the strongest negative influences on various HRV indicators. These associations attenuated greatly on lag 1 d or lag 2 d. Elemental carbon, organic carbon, nitrate, sulfate, arsenic, cadmium, chromium and nickel were consistently associated with reduced HRV parameters in both single-constituent models and constituent-PM2.5 models. ConclusionOur study highlighted the key roles of traffic-related components of PM2.5 in inhibiting cardiac autonomic function.

Fine particulate matter constituents and cause-specific mortality in China: A nationwide modelling study

BackgroundFine particulate matter (with aerodynamic diameter ≤2.5 µm, PM2.5) causes huge disease burden worldwide. However, evidence is still inadequate and inconsistent on the relationships between PM2.5 constituents and mortality, especially in low resource settings. ObjectivesTo evaluate the impact of PM2.5 constituents on cause-specific mortality in China. MethodsWe obtained daily mortality data for 161 communities in 2011–2013 from the Disease Surveillance Point system in China. Daily concentrations of major PM2.5 constituents, including organic carbon (OC), elemental carbon (EC), sulphate (SO42-), nitrate (NO3-) and ammonium (NH4+), were estimated by using the modified Community Multiscale Air Quality model. For each community, we applied quasi-Poisson regression and polynomial distributed lag models to estimate the effects of PM2.5 constituents on cause-specific mortality. Then, the pooled effect estimates were calculated by a random-effect meta-analysis based on the restricted maximum likelihood estimation. Stratification analyses were performed by region, gender, age group and education level to identify the vulnerable populations. ResultsEach interquartile range change of EC, OC, SO42-, NO3- and NH4+ at lag 0–3 day was associated with increments in non-accidental mortality of 0.45% (95%CI: 0.21, 0.69), 1.43% (0.97, 1.89), 0.71% (0.28, 1.15), 0.70% (0.10, 1.30) and 0.95% (0.39, 1.51), respectively. The associations were stronger for the deaths from cardiovascular disease and myocardial infarction, the elderly, illiterates, and people living in the South region. ConclusionsOur findings suggest positive associations between PM2.5 constituents and cause-specific mortality, particularly for myocardial infarction.

How the constituents of fine particulate matter and ozone affect the lung function of children in Tianjin, China.

As the pollution of fine particulate matter (≤ 2.5μg/m3 in aerodynamic diameter; PM2.5) and ozone (O3) is becoming more and more serious in developing countries, we, hereby, investigated the effects of PM2.5, constituents of PM2.5 and O3 on the lung function of children in Tianjin, China. The lung functions of 198 pupils from nine primary schools in Tianjin were examined (repeated five times) during the months of October to December in 2016, 2017 and 2018, respectively. And the mixed-effect models were used to evaluate the effects of air pollutants. A 10μg/m3 increase in PM2.5 and O3-8h might lead to reductions of forced vital capacity (FVC) in 1.03% (- 1.87 to - 0.19%) and 21.09% (- 25.54 to - 16.58%), respectively, while a 10ng/m3 increment in ANY might account for the 166.44% (- 221.32 to - 112.31%) decreases in FVC. PM2.5 and O3-8h might be more harmful to the lung functions of female students and participants with PS exposure at home. And the main sources of pollution resulting in the decrease in pulmonary function might be traffic pollution and coal combustion.

Workflow for comparison of chemical and biological metrics of filter collected PM2.5

There is limited understanding of adverse health effect associations with chemical constituents of fine particulate matter (PM2.5) as well as the underlying mechanisms. We outlined a workflow to assess metrics, beyond concentration, using household and personal PM2.5 filter samples collected in India as a proof of concept for future large-scale studies. Oxidative potential, chemical composition (polycyclic aromatic hydrocarbons and elements), and bioactivity (developmental exposures in zebrafish) were determined. Significant differences were observed in all metrics between personal and household PM2.5 samples. This work established methods to characterize multiple metrics of PM2.5 to ultimately support the identification of more health-relevant metrics than concentration.

Associations between fine particulate matter constituents and daily cardiovascular mortality in Shanghai, China.

Limited evidence is available for the associations between fine particulate matter (PM2.5) constituents and daily cardiovascular disease (CVD) mortality in China. In present study, a time-series analysis was conducted to evaluate the associations of PM2.5 constituents (two carbonaceous fractions, eight water-soluble inorganic ions and fifteen elements) with daily CVD mortality in Pudong New Area of Shanghai, China, from 2014 to 2016. Results showed that the effect estimates for the associations of PM2.5 and its constituents with CVD mortality were generally strongest when using the exposures of the previous two day concentrations. The associations of organic carbon, sulfate, ammonia, potassium, copper, arsenic, and lead with daily CVD mortality were robust to the adjustment of PM2.5 total mass, their collinearity with PM2.5 total mass, and criteria gaseous air pollutants. An interquartile range increase in the previous two day concentrations of PM2.5, organic carbon, sulfate, ammonia, potassium, copper, arsenic, and lead were associated with significant increments of 2.21% (95% confidence interval [95%CI]: 0.54%, 3.88%), 2.83% (95% CIs: 1.16%, 4.50%), 1.90% (95% CIs: 0.35%, 3.45%), 2.29% (95% CIs: 0.80%, 3.77%), 0.94% (95% CIs: 0.13%, 1.75%), 1.53% (95% CIs: 0.37%, 2.69%), 2.08% (95% CIs: 0.49%, 3.68%) and 1.98% (95% CIs: 0.49%, 3.47%) in daily CVD mortality, respectively, in single-pollutant models. In conclusion, this study suggested that organic carbon, sulfate, ammonia, potassium, copper, arsenic, and lead might be mainly responsible for the associations between short-term PM2.5 exposures and increased CVD mortality in Shanghai, China.

The acute effects of fine particulate matter constituents on circulating inflammatory biomarkers in healthy adults

BackgroundSystemic inflammation is considered one of the key mechanisms in the development of cardiovascular diseases induced by fine particulate matter (PM2.5) air pollution. However, evidence concerning the effects of various PM2.5 constituents on circulating inflammatory biomarkers were limited and inconsistent. ObjectivesTo evaluate the associations of short-term exposure to a variety of PM2.5 constituents with circulating inflammatory biomarkers. MethodsWe conducted a panel study from May to October 2016 among 40 healthy adults in Shanghai, China. We monitored the concentrations of 27 constituents of PM2.5. We applied linear mixed-effect models to analyze the associations of PM2.5 and its constituents with 7 inflammatory biomarkers, and further assessed the robustness of the associations by fitting models adjusting for PM2.5 mass and/or their collinearity. Benjamini-Hochberg false discovery rate was used to correct for multiple comparisons. ResultsThe associations of PM2.5 were strongest at lag 0 d with tumor necrosis factor-α (TNF-α), at lag 1 d with interleukin-6, interleukin-8, and interleukin-17A, at lag 02 d with monocyte chemoattractant protein-1 (MCP-1) and intercellular adhesion molecule-1 (ICAM-1). After correcting for multiple comparisons in all models, Cl−, K+, Si, K, As, and Pb were significantly associated with interleukin-8; SO42− and Se were marginally significantly associated with interleukin-8; SO42−, As, and Se were marginally significantly associated with TNF-α; and Si, K, Zn, As, Se, and Pb were marginally significantly associated with MCP-1. ConclusionsOur results suggested that some constituents (SO42−, Cl−, K+, and some elements) might be mainly responsible for systemic inflammation triggered by short-term PM2.5 exposure.

Personal Fine Particulate Matter Constituents, Increased Systemic Inflammation, and the Role of DNA Hypomethylation.

Limited evidence is available on the effects of various fine particulate matter (PM2.5) components on inflammatory cytokines and DNA methylation. We examined whether 16 PM2.5 components are associated with changes in four blood biomarkers, that is, tumor necrosis factor-α (TNF-α), soluble cluster of differentiation 40 ligand (sCD40L), soluble intercellular adhesion molecule-1 (sICAM-1), and fibrinogen, as well as their corresponding DNA methylation levels in a panel of 36 healthy college students in Shanghai, China. We used linear mixed-effect models to evaluate the associations, with controls of potential confounders. We further conducted mediation analysis to evaluate the potential mediation effects of components on inflammatory markers through change in DNA methylation. We observed that several components were consistently associated with TNF-α and fibrinogen as well as their DNA hypomethylation. For example, an interquartile range increase in personal exposure to PM2.5-lead (Pb) was associated with 65.20% (95% CI: 37.07, 99.10) increase in TNF-α and 2.66 (95% CI: 37.07, 99.10) decrease in TNF-α methylation, 30.51% (95% CI: 0.72, 69.11) increase in fibrinogen and 1.25 (95% CI: 0.67, 1.83) decrease in F3 methylation. PM2.5 components were significantly associated with sICAM-1 methylation but not with sICAM-1 protein. DNA methylation mediated 19.89%-41.75% of the elevation in TNF-α expression by various PM2.5 constituents. Our findings provide clues that personal PM2.5 constituents exposure may contribute to increased systemic inflammation through DNA hypomethylation.

The effects of fine particulate matter constituents on exhaled nitric oxide and DNA methylation in the arginase–nitric oxide synthase pathway

BackgroundFine particulate matter (PM2.5) has been widely associated with airway inflammation represented by increased fractional concentration of exhaled nitric oxide (FeNO). However, it remains unclear whether various PM2.5 constituents have different impacts on FeNO and its production process from the arginase (ARG)–nitric oxide synthase (NOS) pathway. ObjectivesTo investigate the acute effects of PM2.5 constituents on FeNO and DNA methylation of genes involved. MethodsWe conducted a longitudinal panel study among 43 young adults in Shanghai, China from May to October in 2016. We monitored the concentrations of 25 constituents of PM2.5. We applied the linear mixed-effect model to evaluate the associations of PM2.5 constituents with FeNO and DNA methylation of the ARG2 and NOS2A genes. ResultsFollowing PM2.5 exposure, NOS2A methylation decreased and ARG2 methylation increased only on the concurrent day, whereas FeNO increased most prominently on the second day. Nine constituents (OC, EC, K, Fe, Zn, Ba, Cr, Se, and Pb) showed consistent associations with elevated FeNO and decreased NOS2A methylation or increased ARG2 methylation in single-constituent models and models adjusting for PM2.5 total mass and collinearity. An interquartile range increase of these constituents was associated with respective decrements of 0.27–1.20 in NOS2A methylation (%5mC); increments of 0.48–1.56 in ARG2 methylation (%5mC); and increments of 7.12%–17.54% in FeNO. ConclusionsOur results suggested that OC, EC, and some metallic elements may be mainly responsible for the development and epigenetic regulation of airway inflammatory response induced by short-term PM2.5 exposure.

Assessing the association between fine particulate matter (PM2.5) constituents and cardiovascular diseases in a mega-city of Pakistan

Concerning PM2.5 concentrations, rapid industrialization, along with increase in cardiovascular disease (CVD) were recorded in Pakistan, especially in urban areas. The degree to which air pollution contributes to the increase in the burden of CVD in Pakistan has not been assessed due to lack of data. This study aims to describe the characteristics of PM2.5 constituents and investigate the impact of individual PM2.5 constituent on cardiovascular morbidity in Karachi, a mega city in Pakistan. Daily levels of twenty-one constituents of PM2.5 were analyzed using samples collected at two sites from fall 2008 to summer 2009 in Karachi. Hospital admission and emergency room visits due to CVD were collected from two large hospitals. Negative Binominal Regression was used to estimate associations between pollutants and the risk of CVD. All PM2.5 constituents were assessed in single-pollutant models and selected constituents were assessed in multi-pollutant models adjusting for PM2.5 mass and gaseous pollutants. The most common CVD subtypes among our participants were ischemic heart disease, hypertension, heart failure, and cardiomyopathy. Extremely high levels of PM2.5 constituents from fossil-fuels combustion and industrial emissions were observed, with notable peaks in winter. The most consistent associations were found between exposure to nickel (5–14% increase per interquartile range) and cardiovascular hospital admissions. Suggestive evidence was also observed for associations between cardiovascular hospital admissions and Al, Fe, Ti, and nitrate. Our findings suggested that PM2.5 generated from fossil-fuels combustion and road dust resuspension were associated with the increased risk of CVD in Pakistan.

PM2.5 metal constituent exposure and stillbirth risk in Harris County, Texas

There is limited evidence on the role of exposure to chemical constituents of fine particulate matter (PM2.5) in risk for stillbirth. Thus, we conducted a case-control study in Harris County, Texas between 2008 and 2013, utilizing a 6:1 ratio of controls to individually matched cases. We linked birth and fetal death records with PM2.5 data from a single air monitoring station and estimated maternal exposures to metal constituents of PM2.5 over the risk period (defined by the gestational length of each case). We applied conditional logistic regression and modeled air pollutant exposures as continuous variables. We observed null associations for most metal constituents (Al, Cr, Cu, Fe, Pb, Mn, Ni, Se and Ti). However, we observed a modest increase in risk for stillbirth (adjusted odds ratio (OR) = 1.11, 95% confidence interval (CI): 1.02, 1.20) associated with a 0.007 μg/m3 interquartile range (IQR) increase in exposure to zinc (Zn) PM2.5. This study adds to the scarce literature evaluating associations between PM2.5 metal constituents and stillbirth and points to the need for further research in this area.

Association of Exposure to Ambient Fine Particulate Matter Constituents With Semen Quality Among Men Attending a Fertility Center in China.

Ambient fine particulate matter (PM2.5) exposure has been linked to decreased semen quality, but the associations between PM2.5 constituent exposures and semen quality remain unknown. We enrolled 1081 men whose partners underwent assisted reproductive technology procedures in Wuhan, China in 2014-2015, and examined their semen quality. Daily average concentrations of PM2.5 constituents including 10 metals/metalloid elements and 4 water-soluble ions were continuously determined for 1 week per month at 2 fixed monitoring stations. Linear mixed models were used to examine the associations of exposures to PM2.5 and its constituents with semen quality. Each interquartile range (36.5 μg/m3) increase in PM2.5 exposure was significantly associated with 8.5% (95% CI: 2.3%, 14.4%) and 8.1% (95% CI: 0.7%, 15.0%) decrease in sperm concentration and total sperm number, respectively. Antimony, cadmium, lead, manganese, and nickel exposures were significantly associated with decreased sperm concentration, whereas manganese exposure was also significantly associated with decreased total motility. Nonsmokers were more susceptible to PM2.5 constituent exposures, especially for antimony and cadmium (all P for effect modification <0.05). These findings suggest that PM2.5 and certain constituents may adversely affect semen quality, especially sperm concentration, and provide new evidence to formulate pollution abatement strategies for male reproductive health.

Hybrid land use regression modeling for estimating spatio-temporal exposures to PM2.5, BC, and metal components across a metropolitan area of complex terrain and industrial sources

Land use regression (LUR) modeling has become a common method for predicting pollutant concentrations and assigning exposure estimates in epidemiological studies. However, few LUR models have been developed for metal constituents of fine particulate matter (PM2.5) or have incorporated source-specific dispersion covariates in locations with major point sources. We developed hybrid AERMOD LUR models for PM2.5, black carbon (BC), and steel-related PM2.5 constituents lead, manganese, iron, and zinc, using fine-scale air pollution data from 37 sites across the Pittsburgh area. These models were designed with the aim of developing exposure estimates for time periods of interest in epidemiology studies. We found that the hybrid LUR models explained greater variability in PM2.5 (R2 = 0.79) compared to BC (R2 = 0.59) and metal constituents (R2 = 0.34–0.55). Approximately 70% of variation in PM2.5 was attributable to temporal variance, compared to 36% for BC, and 17–26% for metals. An AERMOD dispersion covariate developed using PM2.5 industrial emissions data for 207 sources was significant in PM2.5 and BC models; all metals models contained a steel mill-specific PM2.5 emissions AERMOD term. Other significant covariates included industrial land use, commercial and industrial land use, percent impervious surface, and summed railroad length.

The Oxidative Potential of Personal and Household PM2.5 in a Rural Setting in Southwestern China.

The chemical constituents of fine particulate matter (PM2.5) vary by source and capacity to participate in redox reactions in the body, which produce cytotoxic reactive oxygen species (ROS). Knowledge of the sources and components of PM2.5 may provide insight into the adverse health effects associated with the inhalation of PM2.5 mass. We collected 48 h household and personal PM2.5 exposure measurements in the summer months among 50 women/household pairs in a rural area of southwestern China where daily household biomass burning is common. PM2.5 mass was analyzed for ions, trace metals, black carbon, and water-soluble organic matter, as well as ROS-generating capability (oxidative potential) by one cellular and one acellular assay. Crustal enrichment factors and a principal component analysis identified the major sources of PM2.5 as dust, biomass burning, and secondary sulfate. Elements associated with the secondary sulfate source (As, Mo, Zn) had the strongest correlation with increased cellular oxidative potential (Spearman r: 0.74, 0.68, and 0.64). Chemical markers of biomass burning (water-soluble potassium and water-soluble organic matter) had negligible oxidative potential, suggesting that these assays may not be useful as health-relevant exposure metrics in populations that are exposed to high levels of smoke from household biomass burning.

Primary biogenic and anthropogenic sources of organic aerosols in Beijing, China: Insights from saccharides and n-alkanes

Sugars and n-alkanes are important organic constituents of atmospheric fine particulate matter (PM2.5). For better understanding their sources and seasonal variations in urban atmosphere, sugar compounds (anhydrosugars, sugars and sugar alcohols) and homologue n-alkanes (C18–C37) were studied in PM2.5 samples collected from September 2013 to July 2014 in Beijing, China. In general, all measured compounds showed the lowest levels in summer. Higher concentrations of sugar compounds and n-alkanes were observed in winter, probably due to elevated combustion emissions (e.g., coal, biofuel and agricultural residue burning) and stable meteorological conditions during heating season. Levoglucosan was the major sugar species in all seasons particularly in autumn and winter, highlighting the significant contribution of biomass burning to fine organic aerosols throughout the whole year especially in cold seasons. Plant waxes contributed to n-alkanes the most in late spring (54.5%) and the least in winter (11.6%); while fossil fuel combustion had the largest contribution in winter (385 ng m−3). The weak odd-carbon predominance of n-alkanes in wintertime aerosols also suggests fossil fuel combustion as the important source of organic aerosols in the heating season. Soil resuspension, fossil fuel combustion and biomass burning, and secondary sources are the main sources of OC in PM2.5 at Beijing. The seasonal variation in source contributions indicates that meteorological condition is a key factor in controlling PM2.5 levels. Furthermore, dust storms in spring can strongly enhance the atmospheric level of fine organic matter in Beijing.

Short-Term and Long-Term Exposures to Fine Particulate Matter Constituents and Health: A Systematic Review and Meta-Analysis

Short-Term and Long-Term Exposures to Fine Particulate Matter Constituents and Health: A Systematic Review and Meta-Analysis

Fine particulate matter constituents and stress hormones in the hypothalamus–pituitary–adrenal axis

Fine particulate matter (PM2.5) has recently been associated with the activation of the hypothalamus–pituitary–adrenal (HPA) axis, increasing cardiometabolic risks. However, it is unknown which constituents of PM2.5 were mainly responsible for these associations. In a longitudinal panel study with 4 repeated measurements among 43 college students in Shanghai, China, we measured serum levels of corticotropin releasing hormone (CRH), adrenocorticotropic hormone (ACTH) and cortisol, as indicators of HPA axis activation. Then, we evaluated the associations of 22 constituents of PM2.5 with these stress hormones using linear mixed-effect models. During the study period, the average daily concentration of PM2.5 was 41.1 μg/m3. We found that short-term exposure to PM2.5 was associated with elevated levels of the 3 stress hormones. We observed that water-soluble inorganic ions, especially nitrate (NO3−) and ammonium, had stronger influences on 3 hormones. Six metallic elements, including Zn, Mn, Cu, Fe, Br, and Cr, had positive but generally instable associations with 3 hormones. The effects of organic carbon and elemental carbon on hormones were generally weak. When correcting for multiple comparisons using false discovery rate, NO3− was still significantly associated with CRH, but other important associations turned to be insignificant. An interquartile range increase in NO3− on the previous day were associated with 12.13% increase (95% confidence interval: 4.45%, 20.37%) in CRH. Our findings suggested that water-soluble inorganic constituents of PM2.5 (especially, NO3−) might have stronger influences on the activation of HPA axis than carbonaceous and elemental components.