Ambient Particulate Matter Size Distributions Drive Regional and Global Variability in Particle Deposition in the Respiratory Tract

Exposure to PM2.5 modulate the pro-inflammatory and interferon responses against influenza virus infection in a human 3D bronchial epithelium model

Epidemiological studies showed a positive association between exposure to PM2.5 and the severity of influenza virus infection. However, the mechanisms by which PM2.5 can disrupt antiviral defence are still unclear. From this perspective, the objective of this study was to evaluate the effects of PM2.5 on antiviral signalling in the respiratory epithelium using the bronchial Calu-3 cell line grown at the air-liquid interface. Pre-exposure to PM2.5 before infection with the influenza virus was investigated, as well as a co-exposure. Although a physical interaction between the virus and the particles seems possible, no effect of PM2.5 on viral replication was observed during co-exposure, although a downregulation of IFN-β release was associated to PM2.5 exposure. However, pre-exposure slightly increased the viral nucleoprotein production and the pro-inflammatory response. Conversely, the level of the myxovirus resistance protein A (MxA), an interferon-stimulated gene (ISG) induced by IFN-β, was reduced. Therefore, these results suggest that pre-exposure to PM2.5 could alter the antiviral response of bronchial epithelial cells, increasing their susceptibility to viral infection.

A stronger association of mental disorders with smaller particulate matter and a modifying effect of air temperature

Mental disorders (MDs) can be triggered by adverse weather conditions and particulate matter (PM) such as PM2.5 and PM10 (aerodynamic diameter ≤2.5 μm and ≤10 μm). However, there is a dearth of evidence on the role of smaller PM (e.g. PM1, aerodynamic diameter ≤1 μm) and the potential modifying effects of weather conditions. We aimed to collect daily data on emergency department visits and hospitalisations for schizophrenia-, mood-, and stress-related disorders in a densely populated Chinese city (Hefei) between 2016 and 2019. A time-stratified case-crossover analysis was used to examine the short-term association of MDs with PM1, PM2.5, and PM10. The potential modifying effects of air temperature conditions (cold and warm days) were also explored. The three size-fractioned PMs were all associated with an increased risk of MDs; however, the association differed between emergency department visit and hospitalisation. Specifically, PM1 was primarily associated with an increased risk of emergency department visit, whereas PM2.5 was primarily associated with an increased risk of hospitalisation, and PM10 was associated with an increased risk of both emergency department visit and hospitalisation. The PM-MD association appeared to be greatest (although not significant) for PM1 (odds ratio range: 1.014-1.055), followed by PM2.5 (odds ratio range: 1.001-1.009) and PM10 (odds ratio range: 1.001-1.006). Furthermore, the PM-MD association was observed on cold days; notably, the association between PM and schizophrenia-related disorders was significant on both cold and warm days. Our results suggest that the smaller the PM, the greater the risk of MDs, and that the PM-MD association could be determined by air temperature conditions.

Wildfire and African dust aerosol oxidative potential, exposure and dose in the human respiratory tract

Exposure to wildfire smoke and dust can severely affect air quality and health. Although particulate matter (PM) levels and exposure are well-established metrics linking to health outcomes, they do not consider differences in particle toxicity or deposition location in the respiratory tract (RT). Usage of the oxidative potential (OP) exposure may further shape our understanding on how different pollution events impact health. Towards this goal, we estimate the aerosol deposition rates, OP and resulting OP deposition rates in the RT for a typical adult Caucasian male residing in Athens, Greece. We focus on a period when African dust (1-3 of August 2021) and severe wildfires at the northern part of the Attika peninsula and the Evia island, Greece (4-18 of August 2021) affected air quality in Athens. During these periods, the aerosol levels increased twofold leading to exceedances of the World Health Organization (WHO) [15(5) μg m-3] PM10 (PM2.5) air quality standard by almost 100 %. We show that the OP exposure is 1.5-times larger during the wildfire smoke events than during the dust intrusion, even if the latter was present in higher mass loads - because wildfire smoke has a higher specific OP than dust. This result carries two important implications: OP exposure should be synergistically used with other metrics - such as PM levels - to efficiently link aerosol exposure with the resulting health effects, and, certain sources of air pollution (in our case, exposure to biomass burning smoke) may need to be preferentially controlled, whenever possible, owing to their disproportionate contribution to OP exposure and ability to penetrate deeper into the human RT.

Wintertime Formation of Large Sulfate Particles in China and Implications for Human Health

Outdoor air pollution causes millions of premature deaths annually worldwide. Sulfate is a major component of particulate pollution. Winter sulfate observations in China show both high concentrations and an accumulation mode with a modal size >1 μm. However, we find that this observed size distribution cannot be simulated using classical gaseous and aqueous phase formation (CSF) or proposed aerosol-processing formation (APF) mechanisms. Specifically, the CSF simulation underestimates sulfate concentrations by 76% over megacities in China and predicts particle size distributions with a modal size of ∼0.35 μm, significantly smaller than observations. Although incorporating the APF mechanism in the atmospheric chemical model notably improves sulfate concentration simulation with reasonable parameters, the simulated sulfate particle size distribution remains similar to that using the CSF mechanism. We further conduct theoretical analyses and show that particles with diameters <0.3 μm grow rapidly (2-3 s) to 1 μm through the condensation of sulfuric acid in fresh high-temperature exhaust plumes, referred to as in-source formation (ISF). An ISF sulfate source equivalent to 15% of sulfur emissions from fossil fuel combustion largely explains both observed size distributions and mass concentrations of sulfate particles. The findings imply that ISF is a major source of wintertime micron-sized sulfate in China and underscore the importance of considering the size distribution of aerosols for accurately assessing the impacts of inorganic aerosols on radiative forcing and human health.

The impact of coal mine dust characteristics on pathways to respiratory harm: investigating the pneumoconiotic potency of coals

Exposure to dust from the mining environment has historically resulted in epidemic levels of mortality and morbidity from pneumoconiotic diseases such as silicosis, coal workers' pneumoconiosis (CWP), and asbestosis. Studies have shown that CWP remains a critical issue at collieries across the globe, with some countries facing resurgent patterns of the disease and additional pathologies from long-term exposure. Compliance measures to reduce dust exposure rely primarily on the assumption that all "fine" particles are equally toxic irrespective of source or chemical composition. For several ore types, but more specifically coal, such an assumption is not practical due to the complex and highly variable nature of the material. Additionally, several studies have identified possible mechanisms of pathogenesis from the minerals and deleterious metals in coal. The purpose of this review was to provide a reassessment of the perspectives and strategies used to evaluate the pneumoconiotic potency of coal mine dust. Emphasis is on the physicochemical characteristics of coal mine dust such as mineralogy/mineral chemistry, particle shape, size, specific surface area, and free surface area-all of which have been highlighted as contributing factors to the expression of pro-inflammatory responses in the lung. The review also highlights the potential opportunity for more holistic risk characterisation strategies for coal mine dust, which consider the mineralogical and physicochemical aspects of the dust as variables relevant to the current proposed mechanisms for CWP pathogenesis.

PM2.5 and its respiratory tract depositions on blood pressure, anxiety, depression and health risk assessment: A mechanistic study based on urinary metabolome

Effects of fine particulate matter (PM2.5) and regional respiratory tract depositions on blood pressure (BP), anxiety, depression, health risk and the underlying mechanisms need further investigations. A repeated-measures panel investigation among 40 healthy young adults in Hefei, China was performed to explore the acute impacts of PM2.5 exposure and its deposition doses in 3 regions of respiratory tract over diverse lag times on BP, anxiety, depression, health risk, and the potential mechanisms. We collected PM2.5 concentrations, its deposition doses, BP, the Self-Rating Anxiety Scale (SAS) score and the Self-Rating Depression Scale (SDS) score. An untargeted metabolomics approach was used to detect significant urine metabolites, and the health risk assessment model was used to evaluate the non-carcinogenic risks associated with PM2.5. We applied linear mixed-effects models to assess the relationships of PM2.5 with the aforementioned health indicators We further evaluate the non-carcinogenic risks associated with PM2.5. We found deposited PM2.5 dose in the head accounted for a large proportion. PM2.5 and its three depositions exposures at a specific lag day was significantly related to increased BP levels and higher SAS and SDS scores. Metabolomics analysis showed significant alterations in urinary metabolites (i.e., glucoses, lipids and amino acids) after PM2.5 exposure, simultaneously accompanied by activation of the cAMP signaling pathway. Health risk assessment presented that the risk values for the residents in Hefei were greater than the lower limits of non-cancer risk guidelines. This real-world investigation suggested that acute PM2.5 and its depositions exposures may increase health risks by elevating BP, inducing anxiety and depression, and altering urinary metabolomic profile via activating the cAMP signaling pathway. And the further health risk assessment indicated that there are potential non-carcinogenic risks of PM2.5 via the inhalation route in this area.

Characterization of size-fractionated carbonaceous particles in the small to nano-size range in Batam city, Indonesia

A cascade impactor type sampler equipped with an inertial filter was used to collect size-segregated particles down to ultrafine particles (UFPs or PM_0.1) on Batam Island in Sumatra, Indonesia, bordered by Singapore and Malaysia during a wet and the COVID-19 pandemic season in 2021. Carbonaceous species, including organic carbon (OC) and elemental carbon (EC), were analyzed by a thermal/optical carbon analyzer to determine the carbon species and their indices. The average UFP was 3.1 ± 0.9 μg/m³, which was 2-4 times lower than in other cities in Sumatra during the same season in the normal condition. The PMs mass concentration was largely affected by local emissions but long-range transportation of particles from Singapore and Malaysia was also not negligible. The air mass arrived at the sampling site passed the ocean, which introduced out clean air with a low level of PMs. The backward trajectory of the air mass and the largest fraction of OC2 and OC3 in all sizes was identified as being transported from the 2 above countries. OC is the dominant fraction in TC and the ratio of carbonaceous components indicated that origin of all particle sizes was predominantly vehicle emissions. UFPs were dominantly emitted from vehicles exhaust emission, while coarser particles (>10 μm) were influenced by the non-exhaust emissions, such as tire wear. Other particles (0.5-1.0; 1.0-2.5; and 2.5-10 μm) were slightly affected by biomass burning. The effective carbon ratio (ECR) and inhalation dose (ID) related EC indicated that finer particles or UFPs and PM_0.5-1 contributed more to human health and global warming.

Colistin-loaded aerosolizable particles for the treatment of bacterial respiratory infections

Compared to parenteral administration of colistin, its direct pulmonary administration can maximize lung drug deposition while reducing systemic adverse side effects and derived nephrotoxicity. Current pulmonary administration of colistin is carried out by the aerosolization of a prodrug, colistin methanesulfonate (CMS), which must be hydrolized to colistin in the lung to produce its bactericidal effect. However, this conversion is slow relative to the rate of absorption of CMS, and thus only 1.4 % (w/w) of the CMS dose is converted to colistin in the lungs of patients receiving inhaled CMS. We synthesized several aerosolizable nanoparticle carriers loaded with colistin using different techniques and selected particles with sufficient drug loading and adequate aerodynamic behavior to efficiently deliver colistin to the entire lung. Specifically, we carried out (i) the encapsulation of colistin by single emulsion-solvent evaporation with immiscible solvents using polylactic-co-glycolic (PLGA) nanoparticles; (ii) its encapsulation using nanoprecipitation with miscible solvents using poly(lactide-co-glycolide)-block-poly(ethylene glycol) as encapsulating matrix; (iii) colistin nanoprecipitation using the antisolvent precipitation method and its subsequent encapsulation within PLGA nanoparticles; and (iv) colistin encapsulation within PLGA-based microparticles using electrospraying. Nanoprecipitation of pure colistin using antisolvent precipitation showed the highest drug loading (55.0 ± 4.8 wt%) and spontaneously formed aggregates with adequate aerodynamic diameter (between 3 and 5 μm) to potentially reach the entire lung. These nanoparticles were able to completely eradicate Pseudomonas aeruginosa in an in vitro lung biofilm model at 10 µg/mL (MBC). This formulation could be a promising alternative for the treatment of pulmonary infections improving lung deposition and, therefore, the efficacy of aerosolized antibiotics.

The Effects of Trash, Residential Biofuel, and Open Biomass Burning Emissions on Local and Transported PM2.5 and Its Attributed Mortality in Africa

Long-term exposure to ambient fine particulate matter (PM_2.5) is the second leading risk factor of premature death in Sub-Saharan Africa. We use GEOS-Chem to quantify the effects of (a) trash burning, (b) residential solid-fuel burning, and (c) open biomass burning (BB) (i.e., landscape fires) on ambient PM_2.5 and PM_2.5-attributable mortality in Africa. Using a series of sensitivity simulations, we excluded each of the three combustion sources in each of five African regions. We estimate that in 2017 emissions from these three combustion sources within Africa increased global ambient PM_2.5 by 2%, leading to 203,000 (95% confidence interval: 133,000-259,000) premature mortalities yr^-1 globally and 167,000 premature mortalities yr^-1 in Africa. BB contributes more ambient PM_2.5-related premature mortalities per year (63%) than residential solid-fuel burning (29%) and trash burning (8%). Open BB in Central Africa leads to the largest number of PM_2.5-attributed mortalities inside the region, while trash burning in North Africa and residential solid-fuel burning in West Africa contribute the most regional mortalities for each source. Overall, Africa has a unique ambient air pollution profile because natural sources, such as windblown dust and BB, contribute strongly to ambient PM_2.5 levels and PM_2.5-related mortality. Air pollution policies may need to focus on taking preventative measures to avoid exposure to ambient PM_2.5 from these less-controllable sources.

Adverse effects of air pollution-derived fine particulate matter on cardiovascular homeostasis and disease

Air pollution is a rapidly growing major health concern around the world. Atmospheric particulate matter that has a diameter of less than 2.5 µm (PM2.5) refers to an air pollutant composed of particles and chemical compounds that originate from various sources. While epidemiological studies have established the association between PM2.5 exposure and cardiovascular diseases, the precise cellular and molecular mechanisms by which PM2.5 promotes cardiovascular complications are yet to be fully elucidated. In this review, we summarize the various sources of PM2.5, its components, and the concentrations of ambient PM2.5 in various settings. We discuss the experimental findings to date that evaluate the potential adverse effects of PM2.5 on cardiovascular homeostasis and function, and the possible therapeutic options that may alleviate PM2.5-driven cardiovascular damage.

Environmental Exposures and Extracellular Vesicles: Indicators of Systemic Effects and Human Disease

PURPOSE OF REVIEW

Environmental pollutants contribute to the pathogenesis of numerous diseases including chronic cardiovascular, respiratory, and neurodegenerative diseases, among others. Emerging evidence suggests that extracellular vesicles (EVs) may mediate the association of environmental exposures with chronic diseases. The purpose of this review is to describe the impact of common environmental exposures on EVs and their role in linking environmental pollutants to the pathogenesis of chronic systemic diseases.

RECENT FINDINGS

Common environmental pollutants including particulate matter, tobacco smoke, and chemical pollutants trigger the release of EVs from multiple systems in the body. Existing research has focused primarily on air pollutants, which alter EV production and release in the lungs and systemic circulation. Air pollutants also impact the selective loading of EV cargo including microRNA and proteins, which modify the cellular function in recipient cells. As a result, pollutant-induced EVs often contribute to a pro-inflammatory and pro-thrombotic milieu, which increases the risk of pollutant-related diseases including obstructive lung diseases, cardiovascular disease, neurodegenerative diseases, and lung cancer. Common environmental exposures are associated with multifaceted changes in EVs that lead to functional alterations in recipient cells and contribute to the pathogenesis of chronic systemic diseases. EVs may represent emerging targets for the prevention and treatment of diseases that stem from environmental exposures. However, novel research is required to expand our knowledge of the biological action of EV cargo, elucidate determinants of EV release, and fully understand the impact of environmental pollutants on human health.

Environmental Exposures and Lung Aging: Molecular Mechanisms and Implications for Improving Respiratory Health

PURPOSE OF REVIEW

Inhaled environmental exposures cause over 12 million deaths per year worldwide. Despite localized efforts to reduce environmental exposures, tobacco smoking and air pollution remain the urgent public health challenges that are contributing to the growing prevalence of respiratory diseases. The purpose of this review is to describe the mechanisms through which inhaled environmental exposures accelerate lung aging and cause overt lung disease.

RECENT FINDINGS

Environmental exposures related to fossil fuel and tobacco combustion and occupational exposures related to silica and coal mining generate oxidative stress and inflammation in the lungs. Sustained oxidative stress causes DNA damage, epigenetic instability, mitochondrial dysfunction, and cell cycle arrest in key progenitor cells in the lung. As a result, critical repair mechanisms are impaired, leading to premature destruction of the lung parenchyma. Inhaled environmental exposures accelerate lung aging by injuring the lungs and damaging the cells responsible for wound healing. Interventions that minimize exposure to noxious antigens are critical to improve lung health, and novel research is required to expand our knowledge of therapies that may slow or prevent premature lung aging.

Humidity Dependence of the Condensational Growth of α-Pinene Secondary Organic Aerosol Particles

The influence of relative humidity (RH) on the condensational growth of organic aerosol particles remains incompletely understood. Herein, the RH dependence was investigated via a series of experiments for α-pinene ozonolysis in a continuously mixed flow chamber in which recurring cycles of particle growth occurred every 7 to 8 h at a given RH. In 5 h, the mean increase in the particle mode diameter was 15 nm at 0% RH and 110 nm at 75% RH. The corresponding particle growth coefficients, representing a combination of the thermodynamic driving force and the kinetic resistance to mass transfer, increased from 0.35 to 2.3 nm² s^-1. The chemical composition, characterized by O:C and H:C atomic ratios of 0.52 and 1.48, respectively, and determined by mass spectrometry, did not depend on RH. The Model for Simulating Aerosol Interactions and Chemistry (MOSAIC) was applied to reproduce the observed size- and RH-dependent particle growth by optimizing the diffusivities D_b within the particles of the condensing molecules. The D_b values increased from 5 α^-1 × 10^-16 at 0% RH to 2 α^-1 × 10^-12 cm^-2 s^-1 at 75% RH for mass accommodation coefficients α of 0.1 to 1.0, highlighting the importance of particle-phase properties in modeling the growth of atmospheric aerosol particles.

Association of personal fine particulate matter and its respiratory tract depositions with blood pressure in children: From two panel studies

Evidence is limited regarding the acute effects of personal fine particulate matter (PM_2.5) exposure and its respiratory tract depositions on the alteration of children's blood pressure (BP). We conducted 2 longitudinal panel studies in 2 cities to evaluate the relations of 72-h real-time personal PM_2.5 exposure and its depositions in 3 respiratory tract regions over different lag times with BP and the risk of prehypertension and hypertension among 286 children aged 4-12 years. We found the strongest effects of PM_2.5 exposure on increased BP and risk of prehypertension and hypertension at lag 2 day, in dose-response manner, even when PM_2.5 below Chinese Ambient Air Quality Standard (CAAQS) Grade II. Moreover, compared to PM_2.5, tracheobronchial and alveolar depositions displayed more evident effects on BP outcomes. Interestingly, all above relationships were stronger among children in Guangzhou with lower PM_2.5 and its deposited doses than those in Weinan. Additionally, boys and those with daily extra-school activity ≥ 1 h were more susceptible to PM_2.5-induced BP effects with significant interactions. Our results highlighted that short-term PM_2.5 exposure and its respiratory tract depositions were dose-responsive related to higher BP, prevalence of prehypertension and hypertension among children, even when PM_2.5 below CAAQS II.

PM2.5 promotes β cell damage by increasing inflammatory factors in mice with streptozotocin

Emerging evidence indicates that exposure to fine particulate matter contributes to the onset of diabetes. The present study aimed to investigate the mechanism of particulate matters (PM)2.5 affecting glucose homeostasis in mice with type 1 diabetes mellitus. Male C57BL/6 mice were housed under filtered air (FA) or PM2.5 for 12 weeks and then received intraperitoneal injection of streptozotocin (STZ; 40 mg/kg) or acetic buffer daily for 5 days. At 4 weeks after the last injection, fasting glucose was tested. In the plasma and liver, cholesterol levels were determined by cholesterol oxidase-peroxidase and triglyceride levels were determined by triglycerophosphate oxidase-peroxidase. Homeostasis model assessment of β cell function (Homa-β) was computed based on fasting insulin and glucose levels. Interleukin-1β (IL-1β) and tumor necrosis factor-α (TNFα) levels in plasma, visceral adipose tissues, RAW264.7 macrophages and MIN6 pancreatic β cells treated with PM2.5 (0-50 µg/ml) were quantified via ELISA. Before STZ injection, fasting blood glucose (FBG) levels were similar between FA and PM2.5 groups. After STZ injection, FBG levels were higher in mice pre-exposed to PM2.5 compared with those pre-exposed to FA. When taking FBG levels ≥7 mmol/l as the criteria for impaired glucose level, its incidence was 53.3% and 77.8% in FA and PM2.5 groups, respectively. Independent of STZ injection, IL-1β levels in the adipose tissue were upregulated in mice pre-exposed to PM2.5 compared with FA. The addition of PM2.5 stimulated IL-1β and TNFα production in macrophages and pancreatic β cells, and inhibited the secretion of insulin from MIN6 cells in a dose-dependent manner. In conclusion, pre-exposure of PM2.5 impaired pancreatic β cells in mice upon STZ injection, partially via enhanced inflammation, and suppressed the secretion of insulin.

Air Pollution and the Airways: Lessons from a Century of Human Urbanization

Since the industrial revolution, air pollution has become a major problem causing several health problems involving the airways as well as the cardiovascular, reproductive, or neurological system. According to the WHO, about 3.6 million deaths every year are related to inhalation of polluted air, specifically due to pulmonary diseases. Polluted air first encounters the airways, which are a major human defense mechanism to reduce the risk of this aggressor. Air pollution consists of a mixture of potentially harmful compounds such as particulate matter, ozone, carbon monoxide, volatile organic compounds, and heavy metals, each having its own effects on the human body. In the last decades, a lot of research investigating the underlying risks and effects of air pollution and/or its specific compounds on the airways, has been performed, involving both in vivo and in vitro experiments. The goal of this review is to give an overview of the recent data on the effects of air pollution on healthy and diseased airways or models of airway disease, such as asthma or chronic obstructive pulmonary disease. Therefore, we focused on studies involving pollution and airway symptoms and/or damage both in mice and humans.

Predictive and Preventive Mucosal Communications in Particulate Matter Exposure-Linked Renal Distress

Despite research into the epidemiological link between exposure to particulate matter (PM) and renal disorder, there is limited information available on the etiological complexity and molecular mechanisms. Among the early responsive tissues to PM exposure, the mucosal barrier of the airway and alimentary tract may be a crucial source of pathologic mediators leading to inflammatory renal diseases, including chronic kidney disease (CKD). Given that harmful responses and products in mucosa exposed to PM may enter the circulation and cause adverse outcomes in the kidney, the aim of the present review was to address the impact of PM exposure on the mucosal barrier and the vicious feedback cycle in the mucosal environment. In addition to the PM-induced alteration of mucosal barrier integrity, the microbial community has a pivotal role in the xenobiotic metabolism and individual susceptibility to PM toxicity. The dysbiosis-induced deleterious metabolites of PM and nutrients are introduced systemically via a disrupted mucosal barrier, contributing to renal injuries and pathologic severity. In contrast, the progress of mucosa-associated renal disease is counteracted by endogenous protective responses in the mucosa. Along with direct elimination of the toxic mediators, modulators of the mucosal microbial community should provide a promising platform for mucosa-based personalized interventions against renal disorders caused by air pollution.

Field Evaluation of Low-Cost Particulate Matter Sensors for Measuring Wildfire Smoke

Until recently, air quality impacts from wildfires were predominantly determined based on data from permanent stationary regulatory air pollution monitors. However, low-cost particulate matter (PM) sensors are now widely used by the public as a source of air quality information during wildfires, although their performance during smoke impacted conditions has not been thoroughly evaluated. We collocated three types of low-cost fine PM (PM2.5) sensors with reference instruments near multiple fires in the western and eastern United States (maximum hourly PM2.5 = 295 µg/m3). Sensors were moderately to strongly correlated with reference instruments (hourly averaged r2 = 0.52-0.95), but overpredicted PM2.5 concentrations (normalized root mean square errors, NRMSE = 80-167%). We developed a correction equation for wildfire smoke that reduced the NRMSE to less than 27%. Correction equations were specific to each sensor package, demonstrating the impact of the physical configuration and the algorithm used to translate the size and count information into PM2.5 concentrations. These results suggest the low-cost sensors can fill in the large spatial gaps in monitoring networks near wildfires with mean absolute errors of less than 10 µg/m3 in the hourly PM2.5 concentrations when using a sensor-specific smoke correction equation.

Changes in the hospitalization and ED visit rates for respiratory diseases associated with source-specific PM2.5 in New York State from 2005 to 2016

Prior work found increased rates for emergency department (ED) visits for asthma and hospitalizations for chronic obstructive pulmonary disease per unit mass of PM2.5 across New York State (NYS) during 2014-2016 after significant reductions in ambient PM2.5 concentrations had occurred following implementation of various policy actions and major economic disruptions. The associations of source-specific PM2.5 concentrations with these respiratory diseases were assessed with a time-stratified case-cossover design and logistic regression models to identify the changes in the PM2.5 that have led to the apparently increased toxicity per unit mass. The rates of ED visits and hospitalizations for asthma and COPD associated with increases in source-specific PM2.5 concentrations in the prior 1, 4, and 7 days were estimated for 6 urban sites in New York State. Overall, there were similar numbers of significantly increased (n = 9) and decreased rates (n = 8) of respiratory events (asthma and COPD hospitalizations and ED visits) associated with increased source-specific PM2.5 concentrations in the previous 1, 4, and 7 days. Associations of source-specific PM2.5 concentrations with excess rates of hospitalizations for COPD for spark- and compression ignition vehicles increased in the 2014-2016 period, but the values were not statistically significant. Other source types showed inconsistent patterns of excess rates. For asthma ED visits, only biomass burning and road dust showed consistent positive associations with road dust having significant values for most lag times. Secondary nitrate also showed significant positive associations with asthma ED visits in the AFTER period compared to no associations in the prior periods. These results suggest that the relationships of asthma and COPD exacerbation with source-specific PM2.5 are not well defined and further work will be needed to determine the causes of the apparent increases in the per unit mass toxicity of PM2.5 in New York State in the 2014-16 period.

Environmental taxation and regional inequality in China

In order to combat environmental pollution, China enacted the Environmental Protection Tax Law in early 2018. Yet the impacts of the environmental tax on individual regions with different socioeconomic statuses, which are crucial for social justice and public acceptance, remain unclear. Based on a Multi-Regional Input-Output (MRIO) table and a nationally regulated tax payment calculation method, this study analyzes the distributional impacts of an environmental tax based upon province's consumption from both inter-provincial and rural-urban aspects. The national tax revenue based on the current levy mechanism is estimated to be only one seventh of the economic loss from premature mortality caused by ambient particulate matter (PM_2.5). The taxation may slightly alleviate urban-rural inequality but may not be helpful with reducing inter-provincial inequality. We further analyze two alternative levy mechanisms. If each province imposes taxes to products it consumes (rather than produces, as in the current mechanism), with the tax rate linearly dependent on its per capita consumption expenditure, this would moderately increase the national tax revenue and significantly reduce inter-provincial inequality. To better compensate for the economic costs of air pollution and reduce regional inequality, it would be beneficial to increase the tax rate nationwide and implement a levy mechanism based on provincially differentiated levels of consumption and economic status.

Automotive wastes

A review of the literature from 2018 related to automotive wastes is presented. Topics include solid wastes from autobodies, batteries, tires, and vehicle electronics, in addition to sustainable building materials. Treatment and control of automotive pollution is also discussed, as well as potential toxicological and health risks. PRACTITIONER POINTS: Life cycle analyses and sustainable development automotive components were a key focus of the 2018 literature. Automobiles have been identified as point sources for air and water pollution. Research into energy consumption, emissions control, and catalytic converter behavior was conducted to mitigate the impact of automobile emissions. Potential non-point source control measures were identified. These included biological and chemical degradation of pollutants, as well as adsorption of heavy metals.

How do particle number, surface area, and mass correlate with toxicity of diesel particle emissions as measured in chemical and cellular assays?

Increasingly stringent particulate matter (PM) emission standards have brought forth engine design improvements, cleaner-burning fuels, and aftertreatment technologies. Reductions in tailpipe PM mass have concomitantly reduced accumulation-mode particle emissions. However, some strategies promote the emission of nucleation-mode particles, which are typically quantified on a number (PN) basis. We previously demonstrated that PN emissions from heavy-duty diesel vehicles equipped with various aftertreatment systems were inversely correlated, and gravimetric PM mass was positively correlated, with two in vitro assays. This present work expands on the analysis of PM mass and PN with in vitro assays to also include four additional PM metrics: suspended PM mass, active particle surface area, aggregate particle surface area, and accumulation-mode particle number. This new analysis shows that like gravimetric PM mass, suspended particle mass and accumulation mode particle number are well correlated with dithiothreitol consumption rate (DTT) and macrophage reactive oxygen species consumption rate (ROS) assays (R² = 0.61-0.96). Data suggest that PM mass emissions dominated by nucleation-mode particles induce equal or slightly greater toxicity compared to PM mass dominated by accumulation-mode particles. Data also show that among all PM metrics, those used for regulating PM in the United States and Europe, namely gravimetric mass and solid PN are overall most correlated with in vitro toxicity. Moreover, continued exploration of alternative, low-cost, and more appropriate PM metrics is warranted to better understand the reproducibility of these findings on other engine applications, fuel types, and aftertreatment platforms.

A Laboratory Assessment of 120 Air Pollutant Emissions from Biomass and Fossil Fuel Cookstoves

Cookstoves emit many pollutants that are harmful to human health and the environment. However, most of the existing scientific literature focuses on fine particulate matter (PM2.5) and carbon monoxide (CO). We present an extensive data set of speciated air pollution emissions from wood, charcoal, kerosene, and liquefied petroleum gas (LPG) cookstoves. One-hundred and twenty gas- and particle-phase constituents-including organic carbon, elemental carbon (EC), ultrafine particles (10-100 nm), inorganic ions, carbohydrates, and volatile/semivolatile organic compounds (e.g., alkanes, alkenes, alkynes, aromatics, carbonyls, and polycyclic aromatic hydrocarbons (PAHs))-were measured in the exhaust from 26 stove/fuel combinations. We find that improved biomass stoves tend to reduce PM2.5 emissions; however, certain design features (e.g., insulation or a fan) tend to increase relative levels of other coemitted pollutants (e.g., EC ultrafine particles, carbonyls, or PAHs, depending on stove type). In contrast, the pressurized kerosene and LPG stoves reduced all pollutants relative to a traditional three-stone fire (≥93% and ≥79%, respectively). Finally, we find that PM2.5 and CO are not strong predictors of coemitted pollutants, which is problematic because these pollutants may not be indicators of other cookstove smoke constituents (such as formaldehyde and acetaldehyde) that may be emitted at concentrations that are harmful to human health.