Ambient Fine Particulate Matter Research Articles

Long-term exposure to ambient fine particulate matter (PM2.5) and attributable pulmonary tuberculosis notifications in Ningxia Hui Autonomous Region, China: a health impact assessment

IntroductionLong-term exposure to fine particulate matter (≤2.5 µm (PM2.5)) has been associated with pulmonary tuberculosis (TB) notifications or incidence in recent publications. Studies quantifying the relative contribution of long-term PM2.5...

Reduced human fecundity attributable to ambient fine particles in low- and middle-income countries

BackgroundExposure to ambient fine particulate matter (PM2.5) has been associated with reduced human fecundity. However, the attributable burden has not been estimated for low- and middle-income countries (LMICs), where the exposure–response function between PM2.5 and the infertility rate has been insufficiently studied. ObjectiveThis study examined the associations between long-term exposure to PM2.5 and human fecundity indicators, namely the expected time to pregnancy (TTP) and 12-month infertility rate (IR), and then estimated PM2.5-attributable burden of infertility in LMICs. MethodsWe analyzed 164,593 eligible women from 100 Demographic and Health Surveys conducted in 49 LMICs between 1999 and 2021. We assessed PM2.5 exposures during the 12 months before a pregnancy attempt using the global satellite-derived PM2.5 estimates produced by Atmospheric Composition Analysis Group (ACAG). First, we created a series of pseudo-populations with balanced covariates, given different levels of PM2.5 exposure, using a matching approach based on the generalized propensity score. For each pseudo-population, we used 2-stage generalized Gamma models to derive TTP or IR from the probability distribution of the questionnaire-based duration time for the pregnancy attempt before the interview. Second, we used spline regressions to generate nonlinear PM2.5 exposure–response functions for each of the two fecundity indicators. Finally, we applied the exposure–response functions to estimate number of infertile couples attributable to PM2.5 exposure in 118 LMICs. ResultsBased on the Gamma models, each 10 µg/m3 increment in PM2.5 exposure was associated with a TTP increase by 1.7 % (95 % confidence interval [CI]: -2.3 %–6.0 %) and an IR increase by 2.3 % (95 %CI: 0.6 %–3.9 %). The nonlinear exposure–response function suggested a robust effect of an increased IR for high-concentration PM2.5 exposure (>75 µg/m3). Based on the PM2.5-IR function, across the 118 LMICs, the number of infertile couples attributable to PM2.5 exposure exceeding 35 µg/m3 (the first-stage interim target recommended by the World Health Organization global air quality guidelines) was 0.66 million (95 %CI: 0.061–1.43), accounting for 2.25 % (95 %CI: 0.20 %–4.84 %) of all couples affected by infertility. Among the 0.66 million, 66.5 % were within the top 10 % high-exposure infertile couples, mainly from South Asia, East Asia, and West Africa. ConclusionPM2.5 contributes significantly to human infertility in places with high levels of air pollution. PM2.5-pollution control is imperative to protect human fecundity in LMICs.

Long-term exposure to PM2.5 compositions and O3 and their interactive effects on DNA methylation of peripheral brain-derived neurotrophic factor promoter

ABSTRACT This study examined the associations of long-term exposure to ambient fine particulate matter (PM2.5) compositions/ozone with methylation of peripheral brain-derived neurotrophic factor (BDNF) promoters. A total of 101 participants were recruited from a cohort in Shijiazhuang, Hebei province, China. They underwent baseline and follow-up surveys in 2011 and 2015. DNA methylation levels were detected by bisulfite-PCR amplification and pyrosequencing. Participants‘ three-year average levels of PM2.5 compositions and ozone were estimated. Bayesian kernel machine regression (BKMR) models were used to examine the joint effects of pollutants on methylation levels. Exposure to PM2.5 compositions and ozone mixtures at the 75th percentile was associated with increased methylation levels at CpG2 of BDNF promoter (203%, 95% CI: 89, 316) than the lowest level of exposure, and sulfate dominated the effect in the BKMR models.Our findings provide clues to the epigenetic mechanisms for the associations of PM2.5 compositions and ozone with BDNF.

The association of short-term increases in ambient PM2.5 and temperature exposures with stillbirth: racial/ethnic disparities among Medicaid recipients.

Racial/ethnic disparities in the association between short-term (e.g. days, weeks) ambient fine particulate matter (PM2.5) and temperature exposures and stillbirth in the US have been understudied. A time-stratified, case-crossover design using a distributed lag non-linear model (0 to 6-day lag) estimated stillbirth odds due to short-term increases in average daily PM2.5 and temperature exposures among 118,632 Medicaid recipients from 2000-2014. Disparities by maternal race/ethnicity (Black, White, Hispanic, Asian, American Indian) and zip-code level socioeconomic status (SES) were assessed. In the temperature-adjusted model, a 10 μg/m3 increase in PM2.5 concentration was marginally associated with increased stillbirth odds at lag 1 (0.68% 95%CI:[-0.04,1.40]) and lag 2 (0.52% 95%CI:[-0.03,1.06]), but not lag 0-6 (2.80% 95%CI:[-0.81,6.45]). An association between daily PM2.5 concentrations and stillbirth odds was found among Black individuals at the cumulative lag (0-6 days: 9.26% 95%CI:[3.12,15.77]), but not among other races/ethnicities. A stronger association between PM2.5 concentrations and stillbirth odds existed among Black individuals living in zip codes with the lowest median household income (lag0-6:14.13% 95%CI:[4.64,25.79]). Short-term temperature increases were not associated with stillbirth risk among any race/ethnicity. Black Medicaid enrollees, and especially those living in lower SES areas, may be more vulnerable to stillbirth due to short-term increases in PM2.5 exposure.

Adopting electric school buses in the United States: Health and climate benefits

Electric school buses have been proposed as an alternative to reduce the health and climate impacts of the current U.S. school bus fleet, of which a substantial share are highly polluting old diesel vehicles. However, the climate and health benefits of electric school buses are not well known. As they are substantially more costly than diesel buses, assessing their benefits is needed to inform policy decisions. We assess the health benefits of electric school buses in the United States from reduced adult mortality and childhood asthma onset risks due to exposure to ambient fine particulate matter (PM2.5). We also evaluate climate benefits from reduced greenhouse-gas emissions. We find that replacing the average diesel bus in the U.S. fleet in 2017 with an electric bus yields $84,200 in total benefits. Climate benefits amount to $40,400/bus, whereas health benefits amount to $43,800/bus due to 4.42*10-3 fewer PM2.5-attributable deaths ($40,000 of total) and 7.42*10-3 fewer PM2.5-attributable new childhood asthma cases ($3,700 of total). However, health benefits of electric buses vary substantially by driving location and model year (MY) of the diesel buses they replace. Replacing old, MY 2005 diesel buses in large cities yields $207,200/bus in health benefits and is likely cost-beneficial, although other policies that accelerate fleet turnover in these areas deserve consideration. Electric school buses driven in rural areas achieve small health benefits from reduced exposure to ambient PM2.5. Further research assessing benefits of reduced exposure to in-cabin air pollution among children riding buses would be valuable to inform policy decisions.

Continued Rise in Health Burden from Ambient PM2.5 in India under SSP Scenarios Until 2100 despite Decreasing Concentrations.

Forecasting alterations in ambient air pollution and the consequent health implications is crucial for safeguarding public health, advancing environmental sustainability, informing economic decision making, and promoting appropriate policy and regulatory action. However, predicting such changes poses a substantial challenge, requiring accurate data, sophisticated modeling methodologies, and a meticulous evaluation of multiple drivers. In this study, we calculate premature deaths due to ambient fine particulate matter (PM2.5) exposure in India from the 2020s (2016-2020) to the 2100s (2095-2100) under four different socioeconomic and climate scenarios (SSPs) based on four CMIP6 models. PM2.5 concentrations decreased in all SSP scenarios except for SSP3-7.0, with the lowest concentration observed in SSP1-2.6. The results indicate an upward trend in the five-year average number of deaths across all scenarios, ranging from 1.01 million in the 2020s to 4.12-5.44 million in the 2100s. Further analysis revealed that the benefits of reducing PM2.5 concentrations under all scenarios are largely mitigated by population aging and growth. These findings underscore the importance of proactive measures and an integrated approach in India to improve atmospheric quality and reduce vulnerability to aging under changing climate conditions.

Reducing biomass burning is key to decrease PM2.5 exposure in European cities

Throughout the world, ambient fine particulate matter (PM2.5) is the environmental factor that poses the greatest risk to health and most European citizens continue to be exposed to PM2.5 levels well above World Health Organization guidelines. Here we present a comprehensive PM2.5 modelling-based source allocation assessment in 708 urban areas in Europe. The results show that urban cores, together with their commuting zones, contribute an average of 22% to urban PM2.5 concentrations levels. The residential sector is the highest source sector in 56% of cities. Its average contribution to PM2.5 formation is 27%, with a cluster of cities in Northern Italy and Eastern Europe contributing to more than 50%. Industry, agriculture and road transport show average contributions of 18%, 17% and 14%, respectively. Most emissions from residential sectors are anthropogenic primary PM2.5 which includes a condensable fraction. Furthermore, anthropogenic primary PM2.5 represents the precursor with the highest contribution in most cities (72%), contributing an average of 35% to urban PM2.5 levels. Emissions of anthropogenic primary PM2.5 by the residential sector are almost entirely (with exceptions of few countries) due to biomass burning. These results suggest that the residential sector should be a key target of any policy to improve air quality and that climate policies promoting biomass as a climate-neutral fuel could have a detrimental effect on air quality. A more integrated approach to climate and air quality policy design is desirable.

Lung function benefits of traditional Chinese medicine Qiju granules against fine particulate air pollution exposure: a randomized controlled trial.

Multiple targets are considered as the causes of ambient fine particulate matter [aerodynamic diameters of < 2.5 μm (PM2.5)] induced lung function injury. Qiju granules are derived from the traditional Chinese medicine (TCM) formula known as Qi-Ju-Di-Huang-Wan (Lycium, Chrysanthemum, and Rehmannia Formula, QJDHW), which has been traditionally used to treat symptoms such as cough with phlegm, dry mouth and throat, and liver heat. This treatment approach involves attenuating inflammation, oxidative stress, and fibrosis response. This study investigated the effects of Qiju granules on protecting lung function against PM2.5 exposure in a clinical trial. A randomized, double-blinded, and placebo-controlled trial was performed among 47 healthy college students in Hangzhou, Zhejiang Province in China. The participants were randomly assigned to the Qiju granules group or the control group based on gender. Clinical follow-ups were conducted once every 2 weeks during a total of 4 weeks of intervention. Real-time monitoring of PM2.5 concentrations in the individually exposed participants was carried out. Data on individual characteristics, heart rate (HR), blood pressure (BP), and lung function at baseline and during the follow-ups were collected. The effects of PM2.5 exposure on lung function were assessed within each group using linear mixed-effect models. In total, 40 eligible participants completed the scheduled follow-ups. The average PM2.5 level was found to be 64.72 μg/m3 during the study period. A significant negative correlation of lung function with PM2.5 exposure concentrations was observed, and a 1-week lag effect was observed. Forced expiratory volume in one second (FEV1), peak expiratory flow (PEF), maximal mid-expiratory flow (MMEF), forced expiratory flow at 75% of forced vital capacity (FVC) (FEF75), forced expiratory flow at 50% of FVC (FEF50), and forced expiratory flow at 25% of FVC (FEF25) were significantly decreased due to PM2.5 exposure in the control group. Small airway function was impaired more seriously than large airway function when PM2.5 exposure concentrations were increased. In the Qiju granules group, the associations between lung function and PM2.5 exposure were much weaker, and no statistical significance was observed. The results of the study showed that PM2.5 exposure was associated with reduced lung function. Qiju granules could potentially be effective in protecting lung functions from the adverse effects of PM2.5 exposure. identifier: ChiCTR1900021235.

New insight into air pollution-related cardiovascular disease: an adverse outcome pathway framework of PM2.5-associated vascular calcification.

Despite the air quality has been generally improved in recent years, ambient fine particulate matter (PM2.5), a major contributor to air pollution, remains one of the major threats to public health. Vascular calcification is a systematic pathology associated with an increased risk of cardiovascular disease. Although the epidemiological evidence has uncovered the association between PM2.5 exposure and vascular calcification, little is known about the underlying mechanisms. The adverse outcome pathway (AOP) concept offers a comprehensive interpretation of all of the findings obtained by toxicological and epidemiological studies. In this review, reactive oxygen species generation was identified as the molecular initiating event (MIE), which targeted subsequent key events (KEs) such as oxidative stress, inflammation, endoplasmic reticulum stress, and autophagy, from the cellular to the tissue/organ level. These KEs eventually led to the adverse outcome, namely increased incidence of vascular calcification and atherosclerosis morbidity. To the best of our knowledge, this is the first AOP framework devoted to PM2.5-associated vascular calcification, which benefits future investigations by identifying current limitations and latent biomarkers.

Ambient fine particulate matter and daily mortality: a comparative analysis of observed and estimated exposure in 347 cities.

Model-estimated air pollution exposure products have been widely used in epidemiological studies to assess the health risks of particulate matter with diameters of ≤2.5 µm (PM2.5). However, few studies have assessed the disparities in health effects between model-estimated and station-observed PM2.5 exposures. We collected daily all-cause, respiratory and cardiovascular mortality data in 347 cities across 15 countries and regions worldwide based on the Multi-City Multi-Country collaborative research network. The station-observed PM2.5 data were obtained from official monitoring stations. The model-estimated global PM2.5 product was developed using a machine-learning approach. The associations between daily exposure to PM2.5 and mortality were evaluated using a two-stage analytical approach. We included 15.8 million all-cause, 1.5 million respiratory and 4.5 million cardiovascular deaths from 2000 to 2018. Short-term exposure to PM2.5 was associated with a relative risk increase (RRI) of mortality from both station-observed and model-estimated exposures. Every 10-μg/m3 increase in the 2-day moving average PM2.5 was associated with overall RRIs of 0.67% (95% CI: 0.49 to 0.85), 0.68% (95% CI: -0.03 to 1.39) and 0.45% (95% CI: 0.08 to 0.82) for all-cause, respiratory, and cardiovascular mortality based on station-observed PM2.5 and RRIs of 0.87% (95% CI: 0.68 to 1.06), 0.81% (95% CI: 0.08 to 1.55) and 0.71% (95% CI: 0.32 to 1.09) based on model-estimated exposure, respectively. Mortality risks associated with daily PM2.5 exposure were consistent for both station-observed and model-estimated exposures, suggesting the reliability and potential applicability of the global PM2.5 product in epidemiological studies.

Long-term exposure to ambient fine particulate matter and risk of liver cancer in the NIH-AARP Diet and Health Study

BackgroundFine particulate matter (PM2.5) exposure has been associated with liver cancer incidence and mortality in a limited number of studies. We sought to evaluate this relationship for the first time in a U.S. cohort with historical exposure assessment. MethodsWe used spatiotemporal prediction models to estimate annual average historical PM2.5 concentrations (1980–2015) at residential addresses of 499,729 participants in the NIH-AARP Diet and Health Study, a cohort in 6 states (California, Florida, Louisiana, New Jersey, North Carolina, and Pennsylvania) and 2 metropolitan areas (Atlanta, Georgia, and Detroit, Michigan) enrolled in 1995–1996 and followed up through 2017. We used a time-varying Cox model to estimate the association for liver cancer and the predominant histologic type, hepatocellular carcinoma (HCC), per 5 µg/m3 increase in estimated outdoor PM2.5 levels, incorporating a 5-year average, lagged 10 years prior to cancer diagnosis and adjusting for age, sex, race/ethnicity, education level and catchment state. We also evaluated PM2.5 interactions with hypothesized effect modifiers. ResultsWe observed a non-significantly increased risk of liver cancer associated with estimated PM2.5 exposure (Hazard ratio [HR] = 1.05 [0.96–1.14], N = 1,625); associations were slightly stronger for HCC, (84 % of cases; HR = 1.08 [0.98–1.18]). Participants aged 70 or older at enrollment had an increased risk of liver cancer versus other age groups (HR = 1.50 [1.01–2.23]); p-interaction = 0.01) and risk was elevated among participants who did not exercise (HR = 1.81 [1.22–2.70]; p-interaction = 0.01). We found no evidence of effect modification by sex, smoking status, body mass index, diabetes status, or alcohol consumption (p-interaction > 0.05). ConclusionsOur findings in this large cohort suggest that residential ambient PM2.5 levels may be associated with liver cancer risk. Further exploration of the variation in associations by age and physical activity are important areas for future research.

Ambient fine particulate matter is associated with daily outpatient visits for ankylosing spondylitis: A time-series analysis in Beijing, China

Exposure to ambient fine particulate matter (PM2.5) has a great impact on human body's immune system, but the correlation between PM2.5 and ankylosing spondylitis has not yet been clarified. We extracted 58,600 outpatient visits for ankylosing spondylitis from the Beijing Medical Claim Data for Employees database from 2010 to 2017. The percentage of outpatient visits following PM2.5 concentrations was estimated using generalized additive models with Poisson connections. Increase by 10 μ g/m3, PM2.5 is associated with daily outpatient visits for ankylosing spondylitis. In this test, the average concentration of PM2.5 was 86.8 ± 74.3 μ g/m3. For every 10 μg/m3 increase in PM2.5 concentration, there was a 0.34% (95% CI, 0.26–0.42%) increase in the risk of patients who visited the doctor on the same day. Females and younger patients were most susceptible to the impact of PM2.5 exposure (P＜0.05). This study revealed the relationship between exposure to PM2.5 and ankylosing spondylitis, and future research can further confirm this finding and explore the potential mechanisms.

Association of Short-Term Increases in Ambient Fine Particulate Matter With Hospitalization for Asthma or COPD During Wildfire Season and Other Time Periods

BackgroundShort-term increases in air pollution are associated with poor asthma and chronic obstructive pulmonary disease (COPD) outcomes. Short-term elevations in fine particulate matter (PM2.5) due to wildfire smoke are becoming more common. Research QuestionThis study evaluated whether short-term increases in PM2.5 and ozone in wildfire season and in winter inversion season were associated with a composite of emergency or inpatient hospitalization for asthma and for COPD. Study Design and MethodsCase-crossover analyses evaluated 63,976 and 18,514 subjects hospitalized for primary discharge diagnoses of asthma and COPD, respectively, between January 1999 and March 2022. Subjects resided on Utah’s Wasatch Front where PM2.5 and ozone were measured by EPA-based monitors. Odds ratios (OR) were calculated using Poisson regression adjusted for weather variables. ResultsAsthma risk increased on the same day that PM2.5 increased during wildfire season (OR=1.057 per +10 μg/m3, CI: 1.019, 1.097, p=0.003) and winter inversions (OR=1.023 per +10 μg/m3, CI: 1.010, 1.037, p=0.0004). Risk decreased after 1 week, but during wildfire season risk rebounded at a 4-week lag (OR=1.098 per +10 μg/m3, CI: 1.033, 1.167). Asthma risk for adults during wildfire season was highest in the first 3 days after PM2.5 increases, but for children highest risk was delayed by 3-4 weeks. PM2.5 exposure was weakly associated with COPD hospitalization. Ozone exposure was not associated with elevated risks. InterpretationIn a large urban population, short-term increases in PM2.5 during wildfire season were associated with asthma hospitalization and the effect sizes were greater than for PM2.5 during inversion season.

Advances in the Separation and Detection of Secondary Organic Aerosol Produced by Decamethylcyclopentasiloxane (D5) in Laboratory-Generated and Ambient Aerosol.

Decamethylcyclopentasiloxane (D5), a common ingredient in many personal care products (PCPs), undergoes oxidation in the atmosphere, leading to the formation of secondary organic aerosol (SOA). Yet, the specific contributions of D5-derived SOA on ambient fine particulate matter (PM2.5) have not been characterized. This study addresses this knowledge gap by introducing a new analytical method to advance the molecular characterization of oxidized D5 and its detection in ambient aerosol. The newly developed reversed phase liquid chromatography method, in conjunction with high-resolution mass spectrometry, separates and detects D5 oxidation products, enabling new insights into their molecular and isomeric composition. Application of this method to laboratory-generated SOA and urban PM2.5 in New York City expands the number of D5 oxidation products observed in ambient aerosol and informs a list of molecular candidates to track D5-derived SOA in the atmosphere. An oxidation series was observed in which one or more methyl groups in D5 (C10H30O5Si5) is replaced by a hydroxyl group, which indicates the presence of multistep oxidation products in ambient PM2.5. Because of their specificity to PCPs and demonstrated detectability in ambient PM2.5, several oxidation products are proposed as molecular tracers for D5-derived SOA and may prove useful in assessing the impact of PCPs-derived SOA in the atmosphere.

Relationships between long-term exposure to major PM2.5 constituents and outpatient visits and hospitalizations in Guangdong, China

Ambient fine particulate matter (PM2.5) has attracted considerable attention due to its crucial role in the rising global disease burden. Evidence of health risks associated with exposure to PM2.5 and its major constituents is important for advancing hazard assessments and air pollution emission policies. We investigated the relationship between exposure to major constituents of PM2.5 and outpatient visits as well as hospitalizations in Guangdong Province, China, where 127 million residents live in a severe PM2.5 pollution environment. An approach that integrates the generalized weighted quantile sum (gWQS) regression with the difference-in-differences (DID) approach was used to assess the overall mixture effects and relative contributions of each constituent. We observed significant associations between long-term exposure to the mixture of PM2.5 constituents (WQS index) and outpatient visits (IR%, percentage increases in risk per unit WQS index increase:1.73, 95%CI: 1.72, 1.74) as well as hospitalizations (IR%:5.15, 95%CI: 5.11, 5.20). Black carbon (weight: 0.34) and nitrate (weight: 0.60) respectively exhibited the highest contributions to outpatient visits and hospitalizations. The overall mixture effects on outpatient visits and hospitalizations were higher with increased summer air temperatures (IR%: 7.54, 95%CI: 7.33, 7.74 and IR%: 9.55, 95%CI: 8.36, 10.75, respectively) or decreased winter air temperatures (IR%: 1.88, 95%CI: 1.68, 2.08 and IR%: 4.87, 95%CI: 3.73, 6.02, respectively). Furthermore, the overall mixture effects on outpatient visits and hospitalizations were significantly higher in populations with higher socioeconomic status (P < 0.01). It's crucial to address the primary sources of nitrate precursor substances and black carbon (mainly traffic-related and industrial-related air pollutants) and consider the complex interaction effects between air temperature and PM2.5 in the context of climate change. Of particular concern is the need to prioritize healthcare demands in economically disadvantaged regions and to address the health inequalities stemming from the uneven distribution of healthcare resources and PM2.5 pollution.

Indoor and ambient black carbon and fine particulate matter associations with blood biomarkers in COPD patients

BackgroundSystemic inflammation contributes to cardiovascular risk and chronic obstructive pulmonary disease (COPD) pathophysiology. Associations between systemic inflammation and exposure to ambient fine particulate matter (PM ≤ 2.5 μm diameter; PM2.5), and black carbon (BC), a PM2.5 component attributable to traffic and other sources of combustion, infiltrating indoors are not well described. MethodsBetween 2012 and 2017, COPD patients completed in-home air sampling over one-week intervals, up to four times (seasonally), followed by measurement of plasma biomarkers of systemic inflammation, C-reactive protein (CRP) and interleukin-6 (IL-6), and endothelial activation, soluble vascular adhesion molecule-1 (sVCAM-1). Ambient PM2.5, BC and sulfur were measured at a central site. The ratio of indoor/ambient sulfur in PM2.5, a surrogate for fine particle infiltration, was used to estimate indoor BC and PM2.5 of ambient origin. Linear mixed effects regression with a random intercept for each participant was used to assess associations between indoor and indoor of ambient origin PM2.5 and BC with each biomarker. Results144 participants resulting in 482 observations were included in the analysis. There were significant positive associations between indoor BC and indoor BC of ambient origin with CRP [%-increase per interquartile range (IQR);95 % CI (13.2 %;5.2–21.8 and 11.4 %;1.7–22.1, respectively)]. Associations with indoor PM2.5 and indoor PM2.5 of ambient origin were weaker. There were no associations with IL-6 or sVCAM-1. ConclusionsIn homes of patients with COPD without major sources of combustion, indoor BC is mainly attributable to the infiltration of ambient sources of combustion indoors. Indoor BC of ambient origin is associated with increases in systemic inflammation in patients with COPD, even when staying indoors.

AhR Agonistic Components in Urban Particulate Matter Regulate Astrocytic Activation and Function.

Exposure to atmospheric particulate matter (PM) has been found to accelerate the onset of neurological disorders via the induction of detrimental neuroinflammatory responses. To reveal how astrocytes respond to urban atmospheric PM stimulation, a commercially available standard reference material (SRM1648a) was tested in this study on the activation of rat cortical astrocytes. The results showed that SRM1648a stimulation induced both A1 and A2 phenotypes in astrocytes, as characterized by the exposure concentration-dependent increases in Fkbp5, Sphk1, S100a10, and Il6 mRNA levels. Studying the functional alterations of astrocytes indicated that the neurotrophic factors of Gdnf and Ngf were transcriptionally upregulated due to astrocytic A2-type activation. SRM1648a also promoted autonomous motility of astrocytes and elevated the expressions of chemokines. The aryl hydrocarbon receptor (AhR) agonistic components, such as polycyclic aromatic hydrocarbons (PAHs), were recognized to greatly contribute to SRM1648a-induced effects on astrocytes, which was confirmed by the attenuation of PM-disturbed astrocytic effects via AhR blockage. This study, for the first time, uncovered the direct regulation of urban atmospheric PM on astrocytic activation and function and traced the containing bioactive components (e.g., PAHs) with AhR agonistic activity. The findings provided new knowledge on understanding the ambiguous neurological disturbance from ambient fine PM pollution.

Air pollutant emissions and sources in Lao People’s Democratic Republic: a provincial scale analysis for years 2013-2019

Recent rapid economic development in Lao People’s Democratic Republic (PDR) has increased national fuel consumption, vehicle fleet, industrial output, waste generation, and agricultural production. This has contributed to national average ambient fine particulate matter (PM2.5) air pollutant levels that are four times higher than World Health Organisation guidelines. Emission inventories are a key tool in understanding the major sources to these air pollution levels, and provide a starting point to identify where mitigation action can be targeted. A national air pollutant emission inventory has not been developed in Lao PDR and, combined with a limited air quality monitoring network means there is limited capacity to develop and track the effectiveness of mitigation actions. This study describes the first air pollutant emission inventory at the national and provincial scale for Lao PDR, covering 2013–2019. Emissions of nine air pollutants, and two greenhouse gases, were quantified using national statistics and international default emission factors. In 2019, national total PM2.5, Nitrogen Oxides (NOx), Black Carbon (BC), Sulphur Dioxide (SO2), Non-Methane Volatile Organic Carbons (NMVOCs), and Ammonia (NH3) were 125, 83, 9.7, 26, 219, and 99 thousand tonnes respectively. Key source sectors include forest fires, residential cooking, agriculture, electricity generation, and transport. However, the contribution of different sources varies across provinces. Forest fires are the primary source determining the spatial trend of particulate air pollution while residential and agricultural emissions contribute more significantly to rural provinces such as Savannakhet. Key sectors in major urban provinces (Vientiane Capital and Xayaboury) are industry, transport and electricity generation. These sectors are also significant sources of greenhouse gases (CO2 and CH4), demonstrating the potential for identification, evaluation and prioritisation of actions that simultaneously improve air quality and achieve Lao PDR’s international climate change commitments.

Nationwide estimation of daily ambient PM2.5 from 2008 to 2020 at 1 km2 in India using an ensemble approach.

High-resolution assessment of historical levels is essential for assessing the health effects of ambient air pollution in the large Indian population. The diversity of geography, weather patterns, and progressive urbanization, combined with a sparse ground monitoring network makes it challenging to accurately capture the spatiotemporal patterns of ambient fine particulate matter (PM2.5) pollution in India. We developed a model for daily average ambient PM2.5 between 2008 and 2020 based on monitoring data, meteorology, land use, satellite observations, and emissions inventories. Daily average predictions at each 1 km × 1 km grid from each learner were ensembled using a Gaussian process regression with anisotropic smoothing over spatial coordinates, and regression calibration was used to account for exposure error. Cross-validating by leaving monitors out, the ensemble model had an R2 of 0.86 at the daily level in the validation data and outperformed each component learner (by 5-18%). Annual average levels in different zones ranged between 39.7 μg/m3 (interquartile range: 29.8-46.8) in 2008 and 30.4 μg/m3 (interquartile range: 22.7-37.2) in 2020, with a cross-validated (CV)-R2 of 0.94 at the annual level. Overall mean absolute daily errors (MAE) across the 13 years were between 14.4 and 25.4 μg/m3. We obtained high spatial accuracy with spatial R2 greater than 90% and spatial MAE ranging between 7.3-16.5 μg/m3 with relatively better performance in urban areas at low and moderate elevation. We have developed an important validated resource for studying PM2.5 at a very fine spatiotemporal resolution, which allows us to study the health effects of PM2.5 across India and to identify areas with exceedingly high levels.

Estimating the mutually adjusted health effects of short- and long-term exposure to PM2.5 on respiratory mortality in a population-based study

Short- and long-term exposure to ambient fine particulate matter (PM2.5) increased respiratory mortality. Previous studies have reported the dependence between short- and long-term effects, but most studies have estimated them independently. In this study, the mutually adjusted effects of PM2.5 exposure on respiratory mortality in Sichuan Province, China, were explored using a mixed quasi-Poisson regression model. After adjustment, the estimated effects on respiratory mortality decreased with both short- and long-term PM2.5 exposure, especially under short-term exposure, by 7.44%. A 10 μg/m3 increase in long-term PM2.5 exposure increased respiratory mortality by 10.42% (95% CI: 7.37%, 13.55%), which was significantly greater than the 1.12% (95% CI: 0.87%, 1.36%) increase in short-term mortality. Females and those under 65 years old suffered from a greater risk when exposed to PM2.5. Greater short-term effects in warm seasons (1.62%; 95% CI: 1.04%, 2.21%) and greater long-term effects in cold seasons (12.99%; 95% CI: 8.22%, 17.33%) were observed. In addition, a greater short-term effect was found using satellite-based PM2.5 concentrations than monitoring-based concentrations. This study indicated that when estimating the effects of short- and long-term PM2.5 exposure, their dependency could not be ignored; otherwise, both effects would be overestimated, especially for short-term effects. A decreasing PM2.5 concentration is beneficial to population health, especially for females and young people.