Particle deposition in the human lung: Health implications of particulate matter from different sources

Rapid deposition analysis of inhaled aerosols in human airways

A rapid data-driven method for determining regional deposition of inhaled medication aerosols in human airways is presented, which is patient specific. Inhalation patterns, device characteristics, and aerodynamic particle size distribution of medications are considered. The method is developed using dimensional analysis and Buckingham Pi theorem, and provides total, regional, and lobar distributions of aerosol deposition. 34 dimensionless quantities are selected, of which 22 encode features of the airway trees and segmented lobes, 14 pertain to the device and the drug formulation, and 13 the inhalation profile of the subject. The dimensionless correlations are obtained using a large database of computational fluid dynamics results on patient specific airways. The intraclass correlation coefficient between the current method and its training dataset is 0.92. The difference between the predicted average lobar deposition in the six asthma patients and the in-vivo data is 1.3%. The model has the potential to offer insights into the effectiveness of personalized drug delivery in clinical settings and can aid in drug development cycles.

Comparative pathogenicity of influenza virus-induced pneumonia mouse model following intranasal and aerosolized intratracheal inoculation

BACKGROUND

Infection of mice with mouse-adapted strains of influenza virus has been widely used to establish mouse pneumonia models. Intranasal inoculation is the traditional route for constructing an influenza virus-induced pneumonia mouse model, while intratracheal inoculation has been gradually applied in recent years. In this article, the pathogenicity of influenza virus-induced pneumonia mouse models following intranasal and aerosolized intratracheal inoculation were compared.

METHODS

By comparing the two ways of influenza inoculation, intranasal and intratracheal, a variety of indices such as survival rate, body weight change, viral titer and load, pathological change, lung wet/dry ratio, and inflammatory factors were investigated. Meanwhile, the transcriptome was applied for the initial exploration of the mechanism underlying the variations in the results between the two inoculation methods.

RESULTS

The findings suggest that aerosolized intratracheal infection leads to more severe lung injury and higher viral loads in the lungs compared to intranasal infection, which may be influenced by the initial site of infection, sialic acid receptor distribution, and host innate immunity.

CONCLUSION

Intratracheal inoculation is a better method for modelling severe pneumonia in mice than intranasal infection.

Ambient Air Pollution Exposure and Outcomes in Patients Receiving Lung Transplant

Importance

Elevated ambient fine particulate matter (PM2.5) air pollution exposure has been associated with poor health outcomes across several domains, but its associated outcomes among lung transplant recipients are poorly understood.

Objective

To investigate whether greater PM2.5 exposure at the zip code of residence is associated with a higher hazard for mortality and graft failure in patients with lung transplants.

Design, Setting, and Participants

This retrospective cohort study used panel data provided by the United Network for Organ Sharing, which includes patients receiving transplants across all active US lung transplant programs. Adult patients who received lung transplants between May 2005 and December 2016 were included, with a last follow-up of September 10, 2020. Data were analyzed from September 2022 to May 2023.

Exposure

Zip code-level annual PM2.5 exposure was constructed using previously published North American estimates.

Main Outcomes and Measures

The primary outcome was time to death or lung allograft failure after lung transplant. A gamma shared frailty Cox proportional hazards model was used to produce unadjusted and adjusted hazard ratios (HRs) to estimate the association of zip code PM2.5 exposure at the time of transplant with graft failure or mortality.

Results

Among 18 265 lung transplant recipients (mean [SD] age, 55.3 [13.2] years; 7328 female [40.2%]), the resident zip code's annual PM2.5 exposure level was greater than or equal to the Environmental Protection Agency (EPA) standard of 12μg/m3 for 1790 patients (9.8%) and less than the standard for 16 475 patients (90.2%). In unadjusted analysis, median graft survival was 4.87 years (95% CI, 4.57-5.23 years) for recipients living in high PM2.5 areas and 5.84 years (95% CI, 5.71-5.96 years) for recipients in the low PM2.5 group. Having an annual PM2.5 exposure level greater than or equal to the EPA standard 12 μg/m3 was associated with an increase in the hazard of death or graft failure (HR, 1.11; 95% CI, 1.05-1.18; P < .001) in the unadjusted analysis and after adjusting for covariates (HR, 1.08; 95% CI, 1.01-1.15; P = .02). Each 1 μg/m3 increase in exposure was associated with an increase in the hazard of death or graft failure (adjusted HR, 1.01; 95% CI, 1.00-1.02; P = .004) when treating PM2.5 exposure as a continuous variable.

Conclusions and Relevance

In this study, elevated zip code-level ambient PM2.5 exposure was associated with an increased hazard of death or graft failure in lung transplant recipients. Further study is needed to better understand this association, which may help guide risk modification strategies at individual and population levels.

Occurrence and human exposure risk of antibiotic resistance genes in tillage soils of dryland regions: A case study of northern Ningxia Plain, China

Agricultural soils are important source and sink of antibiotic resistance genes (ARGs). However, little is known about the fate of ARGs in dryland soils, while its human exposure risks were seriously overlooked. Taking the northern Ningxia Plain as a case, this study explored the occurrence of ARGs and its relationship with mobile genetic elements (MGEs), pathogens, and environmental factors. Furthermore, the concentrations of airborne ARGs by soil wind erosion and the human exposure doses of soil ARGs were evaluated. The results showed the abundances of different regions ranged from 4.0 × 105 to 1.6 × 106 copies/g. Soil ARGs are driven by MGEs, but multiply impacted by soil properties, nutrition, and bacterial community. Vibrio metschnikovii, Acinetobacter schindleri, and Serratia marcescens are potential pathogenic hosts for ARGs. Further exploration revealed the concentration of ARGs loaded in dust by soil wind erosion reached more than 105 copies/m3, which were even higher than those found in sewage treatment plants and hospitals. Skin contact is the primary route of ARGs exposure, with a maximum dose of 24071.33 copies/kg/d, which is largely attributed to ARGs loaded in dust. This study bridged the gap on ARGs in dryland soils, and provided reference for human exposure risk assessment of soil ARGs.

Evaluation of atmospheric particulate matter pollution characteristics in Shanghai based on biomagnetic monitoring technology

Atmospheric particulate matter (PM) pollution is one of the world's most serious environmental challenges, and it poses a significant threat to environmental quality and human health. Biomagnetic monitoring of PM has great potential to improve spatial resolution and provide alternative indicators for large area measurements, with respect and complementary to standard air quality monitoring stations. In this study, 160 samples of evergreen plant leaves were collected from park green spaces within five different functional areas of Shanghai. Magnetic properties were investigated to understand the extent and nature of particulate pollution and the possible sources, and to assess the suitability of various plant leaves for urban particulate pollution monitoring. The results showed that magnetic particles of the plant leaf-adherent PM were predominantly composed of pseudo-single domain (PSD) and multi-domain (MD) ferrimagnetic particles. Magnolia grandiflora, as a large evergreen arbor with robust PM retention capabilities, proved to be a more suitable candidate for monitoring urban particulate pollution compared to Osmanthus fragrans, a small evergreen arbor, and Aucuba japonica Thunb. var. variegata and Photinia serratifolia, evergreen shrubs. Meanwhile, there were significant differences in the spatial distribution of the magnetic particle content and heavy metal enrichment of the samples, mainly showing regional variations of industrial area > traffic area > commercial area > residential area > clean area. Additionally, the combination with the results of scanning electron microscopy, shows that industrial production (metal smelting, coal burning), transport and other activities are the main sources of particulate pollution. Plant leaves can be used as an effective tool for urban particulate pollution monitoring and assessment of atmospheric particulate pollution characteristics, and the technique provided useful information on particle size, mineralogy and possible sources.

Correlation between Exposure to UFP and ACE/ACE2 Pathway: Looking for Possible Involvement in COVID-19 Pandemic

The overlap between the geographic distribution of COVID-19 outbreaks and pollution levels confirmed a correlation between exposure to atmospheric particulate matter (PM) and the SARS-CoV-2 pandemic. The RAS system is essential in the pathogenesis of inflammatory diseases caused by pollution: the ACE/AngII/AT1 axis activates a pro-inflammatory pathway, which is counteracted by the ACE2/Ang(1-7)/MAS axis, which activates an anti-inflammatory and protective pathway. However, ACE2 is also known to act as a receptor through which SARS-CoV-2 enters host cells to replicate. Furthermore, in vivo systems have demonstrated that exposure to PM increases ACE2 expression. In this study, the effects of acute and sub-acute exposure to ultrafine particles (UFP), originating from different anthropogenic sources (DEP and BB), on the levels of ACE2, ACE, COX-2, HO-1, and iNOS in the lungs and other organs implicated in the pathogenesis of COVID-19 were analyzed in the in vivo BALB/c male mice model. Exposure to UFP alters the levels of ACE2 and/or ACE in all examined organs, and exposure to sub-acute DEP also results in the release of s-ACE2. Furthermore, as evidenced in this and our previous works, COX-2, HO-1, and iNOS levels also demonstrated organ-specific alterations. These proteins play a pivotal role in the UFP-induced inflammatory and oxidative stress responses, and their dysregulation is linked to the development of severe symptoms in individuals infected with SARS-CoV-2, suggesting a heightened vulnerability or a more severe clinical course of the disease. UFP and SARS-CoV-2 share common pathways; therefore, in a "risk stratification" concept, daily exposure to air pollution may significantly increase the likelihood of developing a severe form of COVID-19, explaining, at least in part, the greater lethality of the virus observed in highly polluted areas.

Source Apportionment of Particulate Matter in a Metal Workshop

Metal workshops are workplaces with the substantial production of particulate matter (PM) with high metal content, which poses a significant health risk to workers. The PM produced by different metal processing techniques differs considerably in its elemental composition and size distribution and therefore poses different health risks. In some previous studies, the pollution sources were isolated under controlled conditions, while, in this study, we present a valuable alternative to characterize the pollution sources that can be applied to real working environments. Fine PM was sampled in five units (partially specializing in different techniques) of the same workshop. A total of 53 samples were collected with a temporal resolution of 30 min and 1 h. The mass concentrations were determined gravimetrically, and the elemental analysis, in which the concentrations of 14 elements were determined, was carried out using the X-ray fluorescence technique. Five sources of pollution were identified: background, steel grinding, metal active gas welding, tungsten inert gas welding, and machining. The sources were identified by positive matrix factorization, a statistical method for source apportionment. The identified sources corresponded well with the work activities in the workshop and with the actual sources described in previous studies. It is shown that positive matrix factorization can be a valuable tool for the identification and characterization of indoor sources.

Estimating the health impacts of exposure to Air pollutants and the evaluation of changes in their concentration using a linear model in Iran

In big and industrial cities of developing countries, illness and mortality from long-term exposure to air pollutants have become a serious issue. This research was carried out in 2019-2020 to estimate the health impacts of PM10, NO2 and O3 pollutants by using AirQ+ and R statistical programming software in Arak, Isfahan, Tabriz, Shiraz, Karaj, and Mashhad. Mortality statistics, number of people in required age groups, and amount of pollutants were gathered respectively from different agencies like Statistics and Information Technology of the Ministry of Health, Statistical Center, and Department of Environment and by using Excel, the average 24-hour and 1-hour concentration and maximum 8-hour concentration for PM10, NO2 and O3 pollutants were gathered. We used linear mixed impacts model to account for the longitudinal observations and heterogeneity of the cities. The results of the study showed high number of deaths due to chronic bronchitis in adults, premature death of infants, and respiratory diseases in Mashhad. This research highlights the importance of estimation of health impacts from exposure to air pollutants on residents of the studied cities.

Fine particulate matter (PM2.5) promotes chemoresistance and aggressive phenotype of A549 lung cancer cells

Lung cancer is one of the most aggressive malignancies with a high mortality rate. In large cities, particulate matter (PM) is a common air pollutant. High PM levels with aerodynamic size ≤2.5 μm (PM2.5) associates with lung cancer incidence and mortality. In this work, we explored PM2.5 effects on the behavior of lung cancer cells. To this, we chronically exposed A549 cells to increasing PM2.5 concentrations collected in México City, then evaluating cell proliferation, chemoresponse, migration, invasion, spheroid formation, and P-glycoprotein and N-cadherin expression. Chronic PM2.5 exposure from 1 μg/cm2 stimulated A549 cell proliferation, migration, and chemoresistance and upregulated P-glycoprotein and N-cadherin expression. PM2.5 also induced larger multicellular tumor spheroids (MCTS) and less disintegration compared with control cells. Therefore, these results indicate lung cancer patients exposed to airborne PM2.5 as urban pollutant could develop more aggressive tumor phenotypes, with increased cell proliferation, migration, and chemoresistance.

Inhalation bioaccessibility of imidacloprid in particulate matter: Implications for risk assessment during spraying

Adverse health outcomes due to the inhalation of pesticide residues in atmospheric particulate matter (PM) are gaining global attention. Quantitative health risk assessments of pesticide inhalation exposure highlight the need to understand the bioaccessibility of pesticide residues. Herein, the inhalation bioaccessibility of imidacloprid in PM was determined using three commonly used in vitro lung modeling methods (Artificial Lysosomal Fluid, Gamble Solution, and Simulated Lung Fluid). To validate its feasibility and effectiveness, we evaluated the bioavailability of imidacloprid using a mouse nasal instillation assay. The in vitro inhalation bioaccessibility of imidacloprid was extracted using Gamble Solution with a solid-liquid ratio of 1/1000, an oscillation rate of 150 r/min, and an extraction time of 24 h, showed a strong linear correlation with its in vivo liver-based bioavailability (R2 =0.8928). Moreover, the margin of exposure was incorporated into the inhalation exposure risk assessment, considering both formulations and nozzles. The inhalation unit exposure of imidacloprid for residents was 0.95-4.09 ng/m3. The margin of exposure for imidacloprid was determined to be acceptable when considering inhalation bioaccessibility. Taken together, these results indicate that the inhalation bioaccessibility of pesticides should be incorporated into assessments of human health risks posed by PM particles.

Nano- and microplastic PBK modeling in the context of human exposure and risk assessment

Insufficient data on nano- and microplastics (NMP) hinder robust evaluation of their potential health risks. Methodological disparities and the absence of established toxicity thresholds impede the comparability and practical application of research findings. The diverse attributes of NMP, such as variations in sizes, shapes, and compositions, complicate human health risk assessment. Although probability density functions (PDFs) show promise in capturing this diversity, their integration into risk assessment frameworks is limited. Physiologically based kinetic (PBK) models offer a potential solution to bridge the gap between external exposure and internal dosimetry for risk evaluation. However, the heterogeneity of NMP poses challenges for accurate biodistribution modeling. A literature review, encompassing both experimental and modeling studies, was conducted to examine biodistribution studies of monodisperse micro- and nanoparticles. The literature search in PubMed and Scopus databases yielded 39 studies that met the inclusion criteria. Evaluation criteria were adapted from previous Quality Assurance and Quality Control (QA-QC) studies, best practice guidelines from WHO (2010), OECD guidance (2021), and additional criteria specific to NMP risk assessment. Subsequently, a conceptual framework for a comprehensive NMP-PBK model was developed, addressing the multidimensionality of NMP particles. Parameters for an NMP-PBK model are presented. QA-QC evaluations revealed that most experimental studies scored relatively well (>0) in particle characterizations and environmental settings but fell short in criteria application for biodistribution modeling. The evaluation of modeling studies revealed that information regarding the model type and allometric scaling requires improvement. Three potential applications of PDFs in PBK modeling of NMP are identified: capturing the multidimensionality of the NMP continuum, quantifying the probabilistic definition of external exposure, and calculating the bio-accessibility fraction of NMP in the human body. A framework for an NMP-PBK model is proposed, integrating PDFs to enhance the assessment of NMP's impact on human health.

Evaluating the mortality and health rate caused by the PM2.5 pollutant in the air of several important Iranian cities and evaluating the effect of variables with a linear time series model

All over the world, the level of special air pollutants that have the potential to cause diseases is increasing. Although the relationship between exposure to air pollutants and mortality has been proven, the health risk assessment and prediction of these pollutants have a therapeutic role in protecting public health, and need more research. The purpose of this research is to evaluate the ill-health caused by PM2.5 pollution using AirQ + software and to evaluate the different effects on PM2.5 with time series linear modeling by R software version 4.1.3 in the cities of Arak, Esfahan, Ahvaz, Tabriz, Shiraz, Karaj and Mashhad during 2019-2020. The pollutant hours, meteorology, population and mortality information were calculated by the Environmental Protection Organization, Meteorological Organization, Statistics Organization and Statistics and Information Technology Center of the Ministry of Health, Treatment and Medical Education for 24 h of PM2.5 pollution with Excel software. In addition, having 24 h of PM2.5 pollutants and meteorology is used to the effect of variables on PM2.5 concentration. The results showed that the highest and lowest number of deaths due to natural deaths, ischemic heart disease (IHD), lung cancer (LC), chronic obstructive pulmonary disease (COPD), acute lower respiratory infection (ALRI) and stroke in The effect of disease with PM2.5 pollutant in Ahvaz and Arak cities was 7.39-12.32%, 14.6-17.29%, 16.48-8.39%, 10.43-18.91%, 12.21-22.79% and 14.6-18.54 % respectively. Another result of this research was the high mortality of the disease compared to the mortality of the nose. The analysis of the results showed that by reducing the pollutants in the cities of Karaj and Shiraz, there is a significant reduction in mortality and linear modeling provides a suitable method for air management planning.

Study of sugarcane bagasse/straw combustion and its atmospheric emissions using a pilot-burner

This work conducted experimental combustion on a closed chamber using two different materials: mixture (1:1) sugarcane bagasse/straw and pre-treated biomass. The sampling method was an Andersen cascade impactor with eight stages. Tests were carried out on untreated biomass varying the velocities observed in the sampling duct (4.18; 5.20, 6.85, and 8.21 m.s-1). Pre-treated biomass tests were performed at 4.19 m.s-1 because in this condition there is a higher speed stability inside the duct. During the combustion tests, the concentration of emitted particles was higher for the lower speed range, with an order of 4.19 > 5.40 > 6.85 > 8.21 m.s-1. The higher speeds observed inside the duct behaved as a dragging agent for particulate material. For the tests at the speed of 8.21 m.s-1 where the flow inside the duct was 0.088 m3s-1, this behavior is more evident. Considering the fine diameter particles (< 2.5 µm), they were emitted in a higher concentration, due to the biomass combustion process, which results in higher emission of ultrafine particles. The emission factors (EFs) obtained for PM10 for untreated biomass were in the range of 0.414 and 0.840. On the other hand, considering the pre-treated biomass, these factors were 0.70 and 1.51. The EFs of PM from the burning of the pre-treated biomass were higher when compared to untreated biomass, which is mainly due to the higher temperature of the process due to the higher HHV (higher heating value) of this material, caused by the removal of hemicellulose (4.71 times) and a proportional increase in lignin (1.52 times). Biomass combustion has the potential to partially replace fossil fuels in heat and energy generation. Nevertheless, more stringent and comprehensive legislation should be established to ensure that air quality is maintained. Furthermore, the emission factors obtained in this study might be useful as input data for air quality modeling in the context of sugarcane's burning biomass, thus, contributing to the generation of inventories that include emissions of this nature.

Composition analysis and health risk assessment of the hazardous compounds in cooking fumes emitted from heated soybean oils with different refining levels

The cooking fumes generated from thermal cooking oils contains various of hazardous components and shows deleterious health effects. The edible oil refining is designed to improve the oil quality and safety. While, there remains unknown about the connections between the characteristics and health risks of the cooking fumes and oils with different refining levels. In this study, the hazardous compounds, including aldehydes, ketones, polycyclic aromatic hydrocarbons (PAHs), and particulate matter (PM) in the fumes emitted from heated soybean oils with different refining levels were characterized, and their health risks were assessed. Results demonstrated that the concentration range of aldehydes and ketones (from 328.06 ± 24.64 to 796.52 ± 29.67 μg/m3), PAHs (from 4.39 ± 0.19 to 7.86 ± 0.51 μg/m3), and PM (from 0.36 ± 0.14 to 5.08 ± 0.15 mg/m3) varied among soybean oil with different refining levels, respectively. The neutralized oil showed the highest concentration of aldehydes and ketones, whereas the refined oil showed the lowest. The highest concentration levels of PAHs and PM were observed in fumes emitted from crude oil. A highly significant (p < 0.001) positive correlation between the acid value of cooking oil and the concentrations of PM was found, suggesting that removing free fatty acids is critical for mitigating PM concentration in cooking fumes. Additionally, the incremental lifetime cancer risk (ILCR) values of PAHs and aldehydes were 5.60 × 10-4 to 8.66 × 10-5 and 5.60 × 10-4 to 8.66 × 10-5, respectively, which were substantially higher than the acceptable levels (1.0 × 10-6) established by US EPA. The present study quantifies the impact of edible oil refining on hazardous compound emissions and provides a theoretical basis for controlling the health risks of cooking fumes via precise edible oil processing.

Enhanced mitigation of inhalable particles and fine particle-bound PAHs from a novel hazardous waste-power plant candidate

Emissions of the inhalable particle (dp < 10 μm, PM10) and their harmful compositions from combustion sources have high potential on health risk with nearly no regulation. This study investigates the particle size distribution (PSD), as well as the removal mechanism of PM10 and fine particle (FP)-bound polycyclic aromatic hydrocarbons (PAHs) from the flue gas of a hazardous waste thermal treatment system. It has ultralow regulated emission and becomes a candidate of power generation module. A series of the advanced scrubbers, cyclonic demister, and baghouse was equipped for multi-pollutant control. The moderate or intense low oxygen dilution (MILD) combustion effectively inhibited the PM2.5 generation by volumetric oxidation. Advanced scrubbers removed PM1, PM2.5, and PM10 by 85.24, 68.68, and 97.60%, respectively, which achieved by local supersaturation, heterogeneous condensation of water vapor, and the growth of fine PM. Moreover, the scrubbers effectively scavenged the course PM10 containing the high-molecular-weight PAH homologs onto the water phase but promoted the condensation and absorption of the lighter homologs onto the fine particle surface (dp ∼5.3 μm). The size window (dp = 0.3-1.0 μm) of the minimum efficiency reporting value of a BH filtration led to the peak of FP-PAH mass and BaP equivalent (BaPeq) toxicity at dp = 0.1-0.4 and 0.1-0.8 μm, respectively. Consequently, the synergy of MILD combustion and the SCB-CYC-BH system effectively inhibited the PM2.5, PM10, PM2.5-PAHs, and FP-PAH levels from a waste thermal treatment process and further mitigated the potential health risk.

A Novel Combined Dry Powder Inhaler Comprising Nanosized Ketoprofen-Embedded Mannitol-Coated Microparticles for Pulmonary Inflammations: Development, In Vitro-In Silico Characterization, and Cell Line Evaluation

Pulmonary inflammations such as chronic obstructive pulmonary disease and cystic fibrosis are widespread and can be fatal, especially when they are characterized by abnormal mucus accumulation. Inhaled corticosteroids are commonly used for lung inflammations despite their considerable side effects. By utilizing particle engineering techniques, a combined dry powder inhaler (DPI) comprising nanosized ketoprofen-embedded mannitol-coated microparticles was developed. A nanoembedded microparticle system means a novel advance in pulmonary delivery by enhancing local pulmonary deposition while avoiding clearance mechanisms. Ketoprofen, a poorly water-soluble anti-inflammatory drug, was dispersed in the stabilizer solution and then homogenized by ultraturrax. Following this, a ketoprofen-containing nanosuspension was produced by wet-media milling. Furthermore, co-spray drying was conducted with L-leucine (dispersity enhancer) and mannitol (coating and mucuactive agent). Particle size, morphology, dissolution, permeation, viscosity, in vitro and in silico deposition, cytotoxicity, and anti-inflammatory effect were investigated. The particle size of the ketoprofen-containing nanosuspension was ~230 nm. SEM images of the spray-dried powder displayed wrinkled, coated, and nearly spherical particles with a final size of ~2 µm (nano-in-micro), which is optimal for pulmonary delivery. The mannitol-containing samples decreased the viscosity of 10% mucin solution. The results of the mass median aerodynamic diameter (2.4-4.5 µm), fine particle fraction (56-71%), permeation (five-fold enhancement), and dissolution (80% release in 5 min) confirmed that the system is ideal for local inhalation. All samples showed a significant anti-inflammatory effect and decreased IL-6 on the LPS-treated U937 cell line with low cytotoxicity. Hence, developing an innovative combined DPI comprising ketoprofen and mannitol by employing a nano-in-micro approach is a potential treatment for lung inflammations.

Diesel exhaust particles induce polarization state-dependent functional and transcriptional changes in human monocyte-derived macrophages

Macrophage populations exist on a spectrum between the proinflammatory M1 and proresolution M2 states and have demonstrated the ability to reprogram between them after exposure to opposing polarization stimuli. Particulate matter (PM) has been repeatedly linked to worsening morbidity and mortality following respiratory infections and has been demonstrated to modify macrophage function and polarization. The purpose of this study was to determine whether diesel exhaust particles (DEP), a key component of airborne PM, would demonstrate polarization state-dependent effects on human monocyte-derived macrophages (hMDMs) and whether DEP would modify macrophage reprogramming. CD14+CD16- monocytes were isolated from the blood of healthy human volunteers and differentiated into macrophages with macrophage colony-stimulating factor (M-CSF). Resulting macrophages were left unpolarized or polarized into the proresolution M2 state before being exposed to DEP, M1-polarizing conditions (IFN-γ and LPS), or both and tested for phagocytic function, secretory profile, gene expression patterns, and bioenergetic properties. Contrary to previous reports, we observed a mixed M1/M2 phenotype in reprogrammed M2 cells when considering the broader range of functional readouts. In addition, we determined that DEP exposure dampens phagocytic function in all polarization states while modifying bioenergetic properties in M1 macrophages preferentially. Together, these data suggest that DEP exposure of reprogrammed M2 macrophages results in a highly inflammatory, highly energetic subpopulation of macrophages that may contribute to the poor health outcomes following PM exposure during respiratory infections.NEW & NOTEWORTHY We determined that reprogramming M2 macrophages in the presence of diesel exhaust particles (DEP) results in a highly inflammatory mixed M1/M2 phenotype. We also demonstrated that M1 macrophages are particularly vulnerable to particulate matter (PM) exposure as seen by dampened phagocytic function and modified bioenergetics. Our study suggests that PM causes reprogrammed M2 macrophages to become a highly energetic, highly secretory subpopulation of macrophages that may contribute to negative health outcomes observed in humans after PM exposure.

Adverse effects of exposure to fine particles and ultrafine particles in the environment on different organs of organisms

Particulate pollution is a global risk factor that seriously threatens human health. Fine particles (FPs) and ultrafine particles (UFPs) have small particle diameters and large specific surface areas, which can easily adsorb metals, microorganisms and other pollutants. FPs and UFPs can enter the human body in multiple ways and can be easily and quickly absorbed by the cells, tissues and organs. In the body, the particles can induce oxidative stress, inflammatory response and apoptosis, furthermore causing great adverse effects. Epidemiological studies mainly take the population as the research object to study the distribution of diseases and health conditions in a specific population and to focus on the identification of influencing factors. However, the mechanism by which a substance harms the health of organisms is mainly demonstrated through toxicological studies. Combining epidemiological studies with toxicological studies will provide a more systematic and comprehensive understanding of the impact of PM on the health of organisms. In this review, the sources, compositions, and morphologies of FPs and UFPs are briefly introduced in the first part. The effects and action mechanisms of exposure to FPs and UFPs on the heart, lungs, brain, liver, spleen, kidneys, pancreas, gastrointestinal tract, joints and reproductive system are systematically summarized. In addition, challenges are further pointed out at the end of the paper. This work provides useful theoretical guidance and a strong experimental foundation for investigating and preventing the adverse effects of FPs and UFPs on human health.

Air pollutants in bronchoalveolar lavage fluid and pulmonary tuberculosis: A mediation analysis of gene-specific methylation

Particulate matter (PM) exposure could alter the risk of tuberculosis, but the underlying mechanism is still unclear. We enrolled 132 pulmonary tuberculosis (PTB) patients and 30 controls. Bronchoalveolar lavage fluid samples were collected from all participants to detect organochlorine pesticides, polycyclic aromatic hydrocarbons, metal elements, and DNA methylation of immunity-related genes. We observed that γ-HCH, Bap, Sr, Ag, and Sn were related to an increased risk of PTB, while Cu and Ba had a negative effect. IFN-γ, IL-17A, IL-2, and IL-23 had a higher level in the PTB group, while IL-4 was lower. The methylation of 18 CpG sites was statistically associated with PTB risk. The methylation at the IL-4_06_121 site showed a significant mediating role on γ-HCH, Sr, and Sn. Our study suggests that PM exposure can increase the risk of tuberculosis by affecting DNA methylation and cytokine expression.

Residential greenness alleviated the adverse associations of long-term exposure to ambient PM1 with cardiac conduction abnormalities in rural adults

BACKGROUND

Ambient air pollution was linked to elevated risks of adverse cardiovascular events, and alterations in electrophysiological properties of the heart might be potential pathways. However, there is still lacking research exploring the associations between PM1 exposure and cardiac conduction parameters. Additionally, the interactive effects of PM1 and residential greenness on cardiac conduction parameters in resource-limited areas remain unknown.

METHODS

A total of 27483 individuals were enrolled from the Henan Rural Cohort study. Cardiac conduction parameters were tested by 12-lead electrocardiograms. Concentrations of PM1 were evaluated by satellite-based spatiotemporal models. Levels of residential greenness were assessed using Enhanced Vegetation Index (EVI) and Normalized difference vegetation index (NDVI). Logistic regression models and restricted cubic splines were fitted to explore the associations of PM1 and residential greenness exposure with cardiac conduction abnormalities risk, and the interaction plot method was performed to visualize their interaction effects.

RESULTS

The 3-year median concentration of PM1 was 56.47 (2.55) μg/m3, the adjusted odds rate (ORs) and 95% confidence intervals (CIs) for abnormal HR, PR, QRS, and QTc interval risk in response to 1 μg/m3 increase in PM1 were 1.064 (1.044, 1.085), 1.037 (1.002, 1.074), 1.061 (1.044, 1.077) and 1.046 (1.028, 1.065), respectively. Participants exposure to higher levels of PM1 had increased risks of abnormal HR (OR = 1.221, 95%CI: 1.144, 1.303), PR (OR = 1.061, 95%CI: 0.940, 1.196), QRS (OR = 1.225, 95%CI: 1.161, 1.294) and QTc interval (OR = 1.193, 95%CI: 1.121, 1.271) compared with lower levels of PM1. Negative interactive effects of exposure to PM1 and residential greenness on abnormal HR, QRS, and QTc intervals were observed (Pfor interaction < 0.05).

CONCLUSION

Long-term PM1 exposure was associated with elevated cardiac conduction abnormalities risks, and this adverse association might be mitigated by residential greenness to some extent. These findings emphasize that controlling PM1 pollution and increasing greenness levels might be effective strategies to reduce cardiovascular disease burdens in resource-limited areas.

Size distribution and lung-deposition of ambient particulate matter oxidative potential: A contrast between dithiothreitol and ascorbic acid assays

Particulate matter (PM) inhaled into human lungs causes oxidative stress and adverse health effects through antioxidant depletion (oxidative potential, OP). However, there is limited knowledge regarding the association between the lung-deposited dose (LDD) of PM and OP in extrathoracic (ET), tracheobronchial (TB), and pulmonary (P) regions of human lungs. Dithiothreitol (DTT) and ascorbic acid (AA) assays were employed to measure the OP of PM size fractions to investigate OP distribution in human lungs and identify the chemical drivers. Quasi-ultrafine particles (quasi-UFP, ≤0.49 μm) exhibited high OP deposition in the TB and P regions, while coarse particles (CP, ≥3.0 μm) dominated in the ET region. A plot of extrinsic (per air volume) and intrinsic (per PM mass) OP versus LDD revealed that the OP for fine and coarse particles was greatest in the ET region, whereas the OP of quasi-UFP was greatest in alveoli. The study also demonstrated that extrinsic OP and PM doses are not strongly related. The decline in OP with increasing PM dose reveals the need for further investigation of the antagonistic effects of the chemical compositions. Overall, the results presented herein help address the gap in knowledge regarding the association between the OP and LDD of ambient particles in specific regions of human lungs.

Climate change, air quality, and respiratory health: a focus on particle deposition in the lungs

This review article delves into the multifaceted relationship between climate change, air quality, and respiratory health, placing a special focus on the process of particle deposition in the lungs. We discuss the capability of climate change to intensify air pollution and alter particulate matter physicochemical properties such as size, dispersion, and chemical composition. These alterations play a significant role in influencing the deposition of particles in the lungs, leading to consequential respiratory health effects. The review paper provides a broad exploration of climate change's direct and indirect role in modifying particulate air pollution features and its interaction with other air pollutants, which may change the ability of particle deposition in the lungs. In conclusion, climate change may play an important role in regulating particle deposition in the lungs by changing physicochemistry of particulate air pollution, therefore, increasing the risk of respiratory disease development.

Effects of pre-natal and post-natal exposures to air pollution on onset and recurrence of childhood otitis media

BACKGROUND

Despite mounting evidence linking outdoor air pollution with otitis media (OM), the role of air pollutant(s) exposure during which critical window(s) on childhood OM remains unknown.

OBJECTIVES

We sought to identify the key air pollutant(s) and critical window(s) associated with the onset and recurrent attacks of OM in kindergarten children.

METHODS

A combined cross-sectional and retrospective cohort study involving 8689 preschoolers aged 3-6 years was performed in Changsha, China. From 2013-2020, data on air pollutants were collected from ambient air quality monitoring stations in Changsha, and the exposure concentration to each child at their home address was calculated using the inverse distance weighted (IDW) method. The relationship between air pollution and OM in kindergarten children was studied using multiple logistic regression models.

RESULTS

Childhood lifetime OM was associated with PM2.5, SO2 and NO2, with ORs (95% CI) of 1.43 (1.19-1.71), 1.18 (1.01-1.37) and 1.18 (1.00-1.39) by per IQR increase in utero exposure and with PM2.5, PM2.5-10 and PM10, with ORs = 1.15 (1.00-1.32), 1.25 (1.13-1.40) and 1.49 (1.28-1.74) for entire post-natal exposure, respectively. The 2nd trimester in utero and the post-natal period, especially the 1st year, were key exposure time windows to PM2.5 and PM10 associated with lifetime OM and the onset of OM. Similarly, the 4th gestational month was a critical window for all pollutants except CO exposure in relation to lifetime OM and OM onset, but not recurrent OM attacks. PM2.5 exposure during the nine gestational months and PM10 exposure during the first three years had cumulative effects on OM development. Our subgroup analysis revealed that certain children were more susceptible to the OM risk posed by air pollution.

CONCLUSIONS

Early-life exposure to air pollution, particularly PM2.5 during the middle of gestation and PM10 during the early post-natal period, was associated with childhood OM.

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.

Drug combinations for inhalation: Current products and future development addressing disease control and patient compliance

Pulmonary delivery is an alternative route of administration with numerous advantages over conventional routes of administration. It provides low enzymatic exposure, fewer systemic side effects, no first-pass metabolism, and concentrated drug amounts at the site of the disease, making it an ideal route for the treatment of pulmonary diseases. Owing to the thin alveolar-capillary barrier, and large surface area that facilitates rapid absorption to the bloodstream in the lung, systemic delivery can be achieved as well. Administration of multiple drugs at one time became urgent to control chronic pulmonary diseases such as asthma and COPD, thus, development of drug combinations was proposed. Administration of medications with variable dosages from different inhalers leads to overburdening the patient and may cause low therapeutic intervention. Therefore, products that contain combined drugs to be delivered via a single inhaler have been developed to improve patient compliance, reduce different dose regimens, achieve higher disease control, and boost therapeutic effectiveness in some cases. This comprehensive review aimed to highlight the growth of drug combinations by inhalation over time, obstacles and challenges, and the possible progress to broaden the current options or to cover new indications in the future. Moreover, various pharmaceutical technologies in terms of formulation and device in correlation with inhaled combinations were discussed in this review. Hence, inhaled combination therapy is driven by the need to maintain and improve the quality of life for patients with chronic respiratory diseases; promoting drug combinations by inhalation to a higher level is a necessity.

Bidirectional airflow in lung airway-on-a-chip with matrix-derived membrane elicits epithelial glycocalyx formation

Organ-on-a-chip systems are rapidly advancing as a viable alternative to existing experimental models in respiratory research. To date, however, epithelial cell cultures within lung airway-on-a-chip devices have yet to demonstrate the presence of an epithelial glycocalyx, a thin layer of proteoglycans, glycoproteins, and glycolipids known to play an important role in regulating epithelial function. Here, we demonstrate that an airway-on-a-chip device that incorporates bidirectional flow mimicking breathing cycles in combination with an ultra-thin matrix-derived membrane (UMM) layer can generate a glycocalyx layer comprised of heparan sulfate. Results with this device and airflow system showed dramatic differences of airway epithelial cell viability and expression of tight junctions, cilia, and mucus over a wide range of flow rates when cultured under oscillatory flow. More importantly, for the first time in a microfluidic organ-on-a-chip setting, we achieved the visualization of an airflow-induced epithelial glycocalyx layer. Our experiments highlight the importance of physiological mimicry in developing in vitro models, as bidirectional airflow showed more representative mucociliary differentiation compared to continuous unidirectional airflow. Thus, the lung airway-on-a-chip platform demonstrated in this study holds great potential as a lung epithelial barrier model for studying the mechanisms of various respiratory diseases and for testing the efficacy of therapeutic candidates in the presence of bidirectional airflow and the glycocalyx.

Biogenic Silver Nanoparticles for Targeted Cancer Therapy and Enhancing Photodynamic Therapy

Different conventional therapeutic procedures are utilized globally to manage cancer cases, yet the mortality rate in patients with cancer remains considerably high. Developments in the field of nanotechnology have included novel therapeutic strategies to deal with cancer. Biogenic (green) metallic silver nanoparticles (AgNPs) obtained using plant-mediated protocols are attractive to researchers exploring cancer treatment. Biogenic AgNPs present advantages, since they are cost-effective, easy to obtain, energy efficient, and less toxic compared to chemically and physically obtained AgNPs. Also, they present excellent anticancer abilities thanks to their unique sizes, shapes, and optical properties. This review provides recent advancements in exploring biogenic AgNPs as a drug or agent for cancer treatment. Thus, great attention was paid to the anticancer efficacy of biogenic AgNPs, their anticancer mechanisms, their efficacy in cancer photodynamic therapy (PDT), their efficacy in targeted cancer therapy, and their toxicity.

Predicting particle deposition using a simplified 8-path in silico human lung prototype

Understanding particle deposition in the human lung is crucial for the assessment of environmental pollutants and the design of new drug delivery systems. Traditionally, research has been carried out by experimental analysis, but this generally requires expensive equipment and exposure of volunteers to radiation, resulting in limited data. To overcome these drawbacks, there is an emphasis on the development of numerical models capable of accurate predictive analysis. The most advanced of these computer simulations are based on three-dimensional computational fluid dynamics. Solving the flow equations in a complete, fully resolved lung airway model is currently not feasible due to the computational resources required. In the present work, a simplified lung model is presented and validated for accurate prediction of particle deposition. Simulations are performed for an 8-path approximation to a full lung airway model. A novel boundary condition method is used to ensure accurate results in truncated flow branches. Simulations are performed at a steady inhalation flow rate of 18 l min-1, corresponding to a low activity breathing rate, while the effects of particle size and density are investigated. Comparison of the simulation results with available experimental data shows that reasonably accurate results can be obtained at a small fraction of the cost of a full airway model. The simulations clearly evaluate the effect of both particle size and particle density. Most importantly, the results show an improvement over a previously documented single-path model, both in terms of accuracy and the ability to obtain regional deposition rates. The present model represents an improvement over previously used simplified models, including single-path models. The multi-path reduced airway approach described can be used by researchers for general and patient-specific analyses of particle deposition and for the design of effective drug delivery systems.

Prevalence of occupational respiratory symptoms and associated factors among industry workers in Ethiopia: A systematic review and meta-analysis

BACKGROUND

Occupational respiratory diseases are major global public health problems, particularly for industry workers. Several studies have investigated occupational respiratory symptoms in various parts of Ethiopia. The findings have been inconsistent and inconclusive, and there is no nationally representative data on the subject. Therefore, this study aimed to estimate the pooled prevalence and factors associated with occupational respiratory symptoms among industry workers in Ethiopia (2010-2022).

METHODS

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis framework Guidelines, search was conducted on several international databases including PubMed, CINAHL, African Journals Online, Hinari, Global Health, and Google scholar. The extracted data was analyzed using STATA 14. Random effect model was used to estimate the effect size. Egger regression test and I2 statistics were used to determine potential publication bias and heterogeneity, respectively among the reviewed articles.

RESULTS

The meta-analysis included a total of 15 studies with 5,135 participants, revealing a pooled prevalence of 51.6% (95% CI: 43.6-59.6) for occupational respiratory symptoms among industry workers in Ethiopia. The absence of personal protective equipment (OR = 1.97, 95% CI: [1.17-3.32]), lack of occupational health and safety training (OR = 3.04, 95% CI: [2.36-3.93]), previous dust exposure (OR = 3.17, 95% CI: [2.3-4.37]), poor working environment (OR = 2.4, 95% CI: [1.7-3.2]), work experience greater than five years (OR = 4.04, 95% CI: [1.61-10.16]), smoking (OR = 6.91, 95% CI: [2.94-16.2]), and previous respiratory illness (OR = 4.25, 95% CI: [2.44-7.42]) were found to associate with the symptoms.

CONCLUSIONS

The high prevalence of occupational respiratory symptoms among industry workers in Ethiopia underscores the urgent need for effective interventions. The provision of personal protective equipment and improvement of working environments by the government, industry owners, and other stakeholders are crucial in reducing occupational respiratory symptoms. Additionally, prioritizing occupational health and safety training for industry workers can help prevent and mitigate the impact of occupational respiratory diseases.

REGISTRATION

This systematic review has been registered in the International Prospective Registry of Systematic Review (PROSPERO) with a specific registration number CRD42022383745.

Bergapten ameliorates combined allergic rhinitis and asthma syndrome after PM2.5 exposure by balancing Treg/Th17 expression and suppressing STAT3 and MAPK activation in a mouse model

Combined allergic rhinitis and asthma syndrome (CARAS) causes chronic respiratory inflammation in allergic individuals. Long-term exposure to particulate matter 2.5 (PM2.5; particles 2.5 µm or less in diameter) can aggravate respiratory damage. Bergapten (5-methoxysporalen) is a furocoumarin mostly found in bergamot essential oil and has significant antioxidant, anticancer, and anti-inflammatory activity. This study created a model in which CARAS was exacerbated by PM2.5 exposure, in BALB/c mice and explored the potential of bergapten as a therapeutic agent. The bergapten medication increased ovalbumin (OVA)-specific immunoglobulin (Ig) G2a level in serum and decreased OVA-specific IgE and IgG1 expression. Clinical nasal symptoms diminished significantly, with weakened inflammatory reaction in both the nasal mucosa and lungs. Furthermore, bergapten controlled the T helper (Th)1 to Th2 ratio by increasing cytokines associated with Th1-like interleukin (IL)-12 and interferon gamma and decreasing the Th2 cytokines IL-4, IL-5, and IL-13. Factors closely related to the balance between regulatory T cells and Th17 (such as IL-10, IL-17, Forkhead box protein P3, and retinoic-related orphan receptor gamma) were also regulated. Notably, pro-inflammatory cytokines IL-6, IL-1β, and tumor necrosis factor-alpha were reduced by bergapten, which suppressed the activation of both the signal transducer and activator of transcription 3 signaling pathway and the mitogen-activated protein kinase signaling pathway. Therefore, bergapten might have potential as a therapeutic agent for CARAS.

Contribution of local and surrounding anthropogenic emissions to a particulate matter pollution episode in Zhengzhou, Henan, China

In this study, we simulated the spatial and temporal processes of a particulate matter (PM) pollution episode from December 10-29, 2019, in Zhengzhou, the provincial capital of Henan, China, which has a large population and severe PM pollution. As winter is the high incidence period of particulate pollution, winter statistical data were selected from the pollutant observation stations in the study area. During this period, the highest concentrations of PM_2.5 (atmospheric PM with a diameter of less than 2.5 µm) and PM₁₀ (atmospheric PM with a diameter of less than 10 µm) peaked at 283 μg m^-3 and 316 μg m^-3, respectively. The contribution rates of local and surrounding regional emissions within Henan (emissions from the regions to the south, northwest, and northeast of Zhengzhou) to PM concentrations in Zhengzhou were quantitatively analyzed based on the regional Weather Research and Forecasting model coupled with Chemistry (WRF/Chem). Model evaluation showed that the WRF/Chem can accurately simulate the spatial and temporal variations in the PM concentrations in Zhengzhou. We found that the anthropogenic emissions south of Zhengzhou were the main causes of high PM concentrations during the studied episode, with contribution rates of 14.39% and 16.34% to PM_2.5 and PM₁₀, respectively. The contributions of anthropogenic emissions from Zhengzhou to the PM_2.5 and PM₁₀ concentrations in Zhengzhou were 7.94% and 7.29%, respectively. The contributions of anthropogenic emissions from the area northeast of Zhengzhou to the PM_2.5 and PM₁₀ concentrations in Zhengzhou were 7.42% and 7.18%, respectively. These two areas had similar contributions to PM pollution in Zhengzhou. The area northeast of Zhengzhou had the lowest contributions to the PM_2.5 and PM₁₀ concentrations in Zhengzhou (5.96% and 5.40%, respectively).

Estimating the mortality attributable to indoor exposure to particulate matter of outdoor origin in mainland China

Previous estimations on the premature deaths attributable to indoor ambient particulate matter (PM) with aerodynamic diameter < 2.5 μm (PM_2.5) of outdoor origin only considered the indoor PM_2.5 concentration, which always neglected the impact from the distribution of particle size and the PM deposition in human airways. To tackle this issue, we first calculated the premature deaths due to PM_2.5 was approximately 1,163,864 persons in mainland China in 2018 by using the global disease burden approach. Then, we specified the infiltration factor of PM with aerodynamic diameter < 1 μm (PM₁) and PM_2.5 to estimate the indoor PM pollution. Results showed that average concentrations of indoor PM₁ and PM_2.5 of outdoor origin were 14.1 ± 3.9 μg/m³ and 17.4 ± 5.4 μg/m³, respectively. The indoor PM₁/PM_2.5 ratio of outdoor origin was estimated to be 0.83 ± 0.18, which was 36 % higher than the ambient PM₁/PM_2.5 ratio (0.61 ± 0.13). Furthermore, we calculated the premature deaths from the indoor exposure of outdoor origin was approximately 734,696, accounting for approximately 63.1 % of total deaths. Our results are 12 % higher than previous estimations neglecting the impact from the distribution disparities of PM between indoor and outdoor. Regarding the cause-specific diseases, indoor PM_2.5 exposure of outdoor origin accounted for 293,379 deaths to ischemic heart disease, followed by 158,238 deaths to chronic obstructive pulmonary disease, 134,390 deaths to stroke, 84,346 cases to lung cancer, 52,628 deaths to lower respiratory tract infection, and 11,715 deaths to type 2 diabetes. In addition, we for the first time estimated the indoor PM₁ of outdoor origin has led to approximately 537,717 premature deaths in mainland China. Our results have well demonstrated the health impact may be approximately 10 % higher when considering the effects from infiltration and respiratory tract uptake and physical activity levels, comparing to the treatment that only used outdoor PM concentration.

Computational fluid-particle dynamics modeling of ultrafine to coarse particles deposition in the human respiratory system, down to the terminal bronchiole

BACKGROUND AND OBJECTIVES

Suspended respirable airborne particles are associated with human health risks and especially particles within the range of ultrafine (< 0.1 μm) or fine (< 2.5 μm) have a high possibility of penetrating the lung region, which is concerned to be closely related to the bronchial or alveoli tissue dosimetry. Nature complex structure of the respiratory system requires much effort to explore and comprehend the flow and the inhaled particle dynamics for precise health risk assessment. Therefore, this study applied the computational fluid-particle dynamics (CFPD) method to elucidate the deposition characteristics of ultrafine-to-coarse particles in the human respiratory tract from nostrils to the 16^th generation of terminal bronchi.

METHODS

The realistic bronchi up to the 8^th generation are precisely and perfectly generated from computed tomography (CT) images, and an artificial model compensates for the 9^th-16^th bronchioles. Herein, the steady airflow is simulated at constant breathing flow rates of 7.5, 15, and 30 L/min, reproducing human resting-intense activity. Then, trajectories of the particle size ranging from 0.002 - 10 μm are tracked using a discrete phase model.

RESULTS

Here, we report reliable results of airflow patterns and particle deposition efficiency in the human respiratory system validated against experimental data. The individual-related focal point of ultrafine and fine particles deposition rates was actualized at the 8^th generation; whilst the hot-spot of the deposited coarse particles was found in the 6^th generation. Lobar deposition characterizes the dominance of coarse particles deposited in the right lower lobe, whereas the left upper-lower and right lower lobes simultaneously occupy high deposition rates for ultrafine particles. Finally, the results indicate a higher deposition in the right lung compared to its counterpart.

CONCLUSIONS

From the results, the developed realistic human respiratory system down to the terminal bronchiole in this study, in coupling with the CFPD method, delivers the accurate prediction of a wide range of particles in terms of particle dosimetry and visualization of site-specific in the consecutive respiratory system. In addition, the series of CFPD analyses and their results are to offer in-depth information on particle behavior in human bronchioles, which may benefit health risk assessment or drug delivery studies.

Wintertime aerosol properties of urban desert region of western India: Implications in regional climate assessment

This study assessed the inter-relation between physiochemical and optical characteristics of aerosols measured at a desert-urban region affected by anthropogenic sources and desert dust during October 2020 to January 2021. Based on horizontal visibility and measured PM_2.5 concentration, clear (37 %), light (33 %) and high (31 %) pollution periods were identified. Elemental and organic carbon (50 ± 15 μgm^-3_; 31 %) and secondary inorganics (53 ± 21 μgm^-3; 33 %) dominated the PM_2.5 mass (160 ± 4 μgm^-3) during high pollution period with low dust (14 ± 7 μgm^-3; 8 %) content. Interestingly, the clear pollution period was also influenced by carbonaceous fraction (19 ± 8 μgm^-3; 32 %) and secondary inorganics (19 ± 5 μgm^-3; 32 %), but the PM_2.5 concentrations (59 ± 9 μgm^-3) were ∼ one-third as compared to high pollution period. High scattering coefficients were observed which were comparable to highly polluted Indian city like Delhi. An exponential increase in non-absorbing material was observed and showed clear influence on light absorption capacity of EC and dust due to coating/mixing. High absorption Ångström exponent (AAE) >0.6 was observed for the ratio of non-absorbing to light absorbing components (LAC) in the range of 1-2.5 and EC/PM_2.5 fraction of 7-14 %. While further increase in non-absorbing to absorbing components ratio > 4 and low amount of EC (<4 %) tend to decrease AAE below 0.4. Higher mass absorption cross-section (>30 m²g^-1 of EC) was observed when 4-10 % EC fraction of PM_2.5 associated with 1.5-3.5 times non-absorbing components to total absorbing components. Likewise, absorption enhanced by three to five folds compared to uncoated EC for low EC fraction (3-6 %) in PM_2.5, but high non-absorbing to absorbing component ratio (>2.5). Interestingly, absorption was minimally amplified for nominal coating fraction associated with significant core materials or vice-versa. These findings have implications not only in regional climate assessment but also for other regions with comparable geography and source-mixes.

A systematic review of transportation carbon emissions based on CiteSpace

Transportation sector has become a major contributor to the escalation of carbon emissions and subsequent climate change. In this study, a bibliometric analysis was conducted using CiteSpace on published papers (1991-2022). Then a theoretical framework was proposed through traditional content analysis from three aspects: measurement, mechanism analysis, and low-carbon pathways analysis. The clustering results show that the research topics have involved mainly factor analysis, evaluation, system analysis, control measurement and pollutants. A further summary of the content of the relevant literature shows that there are five main accounting methods for measuring transportation carbon emissions (TCEs), which can be applied to different scenarios. Studies involving the spatio-temporal distribution of TCEs is limited and mainly focus on macroperspectives. The mechanism of TCEs involves three main aspects: system assessment, efficiency measurement, and driver analysis, which serve to identify the internal patterns of TCEs. Finally, the outlook regarding TCEs is presented.

Particle Deposition in Large-Scale Human Tracheobronchial Airways Predicted by Single-Path Modelling

The health effects of particles are directly related to their deposition patterns (deposition site and amount) in human airways. However, estimating the particle trajectory in a large-scale human lung airway model is still a challenge. In this work, a truncated single-path, large-scale human airway model (G3-G10) with a stochastically coupled boundary method were employed to investigate the particle trajectory and the roles of their deposition mechanisms. The deposition patterns of particles with diameters (dp) of 1-10 μm are investigated under various inlet Reynolds numbers (Re = 100-2000). Inertial impaction, gravitational sedimentation, and combined mechanism were considered. With the increasing airway generations, the deposition of smaller particles (dp < 4 μm) increased due to gravitational sedimentation, while that of larger particles decreased due to inertial impaction. The obtained formulas of Stokes number and Re can predict the deposition efficiency due to the combined mechanism in the present model, and the prediction can be used to assess the dose-effect of atmospheric aerosols on the human body. Diseases in deeper generations are mainly attributed to the deposition of smaller particles under lower inhalation rates, while diseases at the proximal generations mainly result from the deposition of larger particles under higher inhalation rates.

Effects of PM2.5 Exposure on the ACE/ACE2 Pathway: Possible Implication in COVID-19 Pandemic

Particulate matter (PM) is a harmful component of urban air pollution and PM2.5, in particular, can settle in the deep airways. The RAS system plays a crucial role in the pathogenesis of pollution-induced inflammatory diseases: the ACE/AngII/AT1 axis activates a pro-inflammatory pathway counteracted by the ACE2/Ang(1-7)/MAS axis, which in turn triggers an anti-inflammatory and protective pathway. However, ACE2 acts also as a receptor through which SARS-CoV-2 penetrates host cells to replicate. COX-2, HO-1, and iNOS are other crucial proteins involved in ultrafine particles (UFP)-induced inflammation and oxidative stress, but closely related to the course of the COVID-19 disease. BALB/c male mice were subjected to PM2.5 sub-acute exposure to study its effects on ACE2 and ACE, COX-2, HO-1 and iNOS proteins levels, in the main organs concerned with the pathogenesis of COVID-19. The results obtained show that sub-acute exposure to PM2.5 induces organ-specific modifications which might predispose to greater susceptibility to severe symptomatology in the case of SARS-CoV-2 infection. The novelty of this work consists in using a molecular study, carried out in the lung but also in the main organs involved in the disease, to analyze the close relationship between exposure to pollution and the pathogenesis of COVID-19.

Development and Optimisation of Inhalable EGCG Nano-Liposomes as a Potential Treatment for Pulmonary Arterial Hypertension by Implementation of the Design of Experiments Approach

Epigallocatechin gallate (EGCG), the main ingredient in green tea, holds promise as a potential treatment for pulmonary arterial hypertension (PAH). However, EGCG has many drawbacks, including stability issues, low bioavailability, and a short half-life. Therefore, the purpose of this research was to develop and optimize an inhalable EGCG nano-liposome formulation aiming to overcome EGCG's drawbacks by applying a design of experiments strategy. The aerodynamic behaviour of the optimum formulation was determined using the next-generation impactor (NGI), and its effects on the TGF-β pathway were determined using a cell-based reporter assay. The newly formulated inhalable EGCG liposome had an average liposome size of 105 nm, a polydispersity index (PDI) of 0.18, a zeta potential of -25.5 mV, an encapsulation efficiency of 90.5%, and a PDI after one month of 0.19. These results are in complete agreement with the predicted values of the model. Its aerodynamic properties were as follows: the mass median aerodynamic diameter (MMAD) was 4.41 µm, the fine particle fraction (FPF) was 53.46%, and the percentage of particles equal to or less than 3 µm was 34.3%. This demonstrates that the novel EGCG liposome has all the properties required to be inhalable, and it is expected to be deposited deeply in the lung. The TGFβ pathway is activated in PAH lungs, and the optimum EGCG nano-liposome inhibits TGFβ signalling in cell-based studies and thus holds promise as a potential treatment for PAH.

Particulate air pollution in the Copenhagen metro part 1: Mass concentrations and ventilation

The Copenhagen Metro comprises four lines, the M1, M2, M3 and M4, with 25 subterranean stations and an additional 14 stations above ground, serving ca. 80 million passengers annually. In this study we measure fine particulate matter (PM_2.5) and carbon dioxide (CO₂) concentrations in stations and in trains across the entire system. In partially underground lines, high PM_2.5 concentrations with an average of 109 μg m^-3 are found in below-ground stations. The observed correlation between PM_2.5 concentration and distance between a station and a tunnel exit is attributed to ventilation via the piston effect. The piston effect via tunnel draught relief shafts was therefore found to be relatively limited. Filter samples of particulate matter are analysed using particle-induced X-ray emission and show an iron content of 88.6 % by mass which is quite different from above-ground particulate matter and consistent with particle production by train wheels, rails and brakes. The average concentration measured at the stations of a recently opened (2019) fully underground M3 closed loop line is 168 μg m^-3, further demonstrating that while piston effect-driven ventilation is effective in close proximity to tunnel openings, it is relatively limited via tunnel draught relief shafts. Measurements onboard trains show even higher PM_2.5 concentrations and the patterns in CO₂ concentrations suggest carriage ventilation by tunnel air. Ventilation via doors during platform stops caused a drop in observed PM (and CO₂) at stations, but the system is surprisingly polluted despite its recent construction. CO₂ mixing ratios ranged from ambient to around 600 ppm. Measures should be taken to control PM levels using a combination of source control and increased clean air supply of the Copenhagen and other similar metro systems.

The influence of air pollution exposure on the short- and long-term health benefits associated with active mobility: A systematic review

Active mobility (AM), defined as walking and cycling for transportation, can improve health through increasing regular physical activity. However, these health improvements could be outweighed by harm from inhaling traffic-related air pollutants during AM participation. The interaction of AM and air pollutants on health is complex physiologically, manifesting as acute changes in health indicators that may lead to poor long-term health consequences. The aim of this study was to systematically review the current evidence of effect modification by air pollution (AP) on associations between AM and health indicators. Studies were included if they examined associations between AM and health indicators being modified by AP or, conversely, associations between AP and health indicators being modified by AM. Thirty-three studies met eligibility criteria. The main AP indicators studied were particulate matter, ultrafine particles, and nitrogen oxides. Most health indicators studied were grouped into cardiovascular and respiratory indicators. There is evidence of a reduction by AP, mainly ultrafine particles and PM_2.5, in the short-term health benefits of AM. Multiple studies suggest that long-term health benefits of AM are not negatively associated with levels of the single traffic-related pollutant NO₂. However, other studies reveal reduced long-term health benefits of AM in areas affected by high levels of pollutant mixtures. We recommend that future studies adopt consistent and rigorous study designs and include reporting of interaction testing, to advance understanding of the complex relationships between AM, AP, and health indicators.

Particulate PCDD/F size distribution and potential deposition in respiratory system from a hazardous waste thermal treatment process

The particulate polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) of various sizes produced from the waste incinerators might have different toxicities, deposition characteristics, and potential health effects in the respiratory system, and their total toxicity equivalent (TEQ) concentration has been strictly regulated in recent years. There is a knowledge gap on the effects of air pollution control devices on particle size distributions (PSDs) of PCDD/Fs and their TEQ deposition. A hazardous waste thermal treatment plant equipped with an advanced scrubber, a cyclone demister, and activated carbon adsorption coupled with a baghouse filtration was investigated in this study. An 8-stage impactor was used to collect the particle distribution of PM₁₀ and bounded PCDD/Fs from the gas stream at four sampling points located before and after each control unit. A "TEQ_DE" index is defined for the toxicity deposition of PM₁₀-PCDD/F in the respiratory system. The advanced scrubbers significantly reduced the PM₁₀-PCDD/F levels, especially for those with sizes ≥0.6 and ≤ 0.4 μm. Additionally, the cyclone also showed a better performance than the general dry gas treatment but had an efficiency drop with 1.5-4 μm particles. The PM₁₀-PCDD/F loads in the final adsorption-filtration unit were eased and effectively removed the PM₁₀-PCDD/Fs to sizes ≤0.5 or≥1.5 μm. The total TEQ_DE was 0.00052 ng WHO-TEQ Nm^-3 and had a peak level of 0.000157 ng WHO-TEQ Nm^-3 at 1.2 μm. PSDs were more sensitive to the PSDs of PM mass at high PM levels but strongly correlated with the PSDs of "PM₁₀-PCDD/Fs/PM₁₀" at low PM₁₀ loads. Consequently, the advanced control system could effectively remove the PM₁₀-PCDD/Fs and might extend the adsorption-filtration lifetime. However, the PM₁₀-PCDD/Fs ≤ 0.4 μm had a higher TEQ deposition rate and should be further considered in emissions and ambient air quality evaluations.

Climate-mediated air pollution associated with COPD severity

Air pollution has been reported to be associated with chronic obstructive pulmonary disease (COPD). Our study aim was to examine the mediating effects of air pollution on climate-associated health outcomes of COPD patients. A cross-sectional study of 117 COPD patients was conducted in a hospital in Taiwan. We measured the lung function, 6-min walking distance, oxygen desaturation, white blood cell count, and percent emphysema (low attenuation area, LAA) and linked these to 0-1-, 0-3-, and 0-5-year lags of individual-level exposure to relative humidity (RH), temperature, and air pollution. Linear regression models were conducted to examine associations of temperature, RH, and air pollution with severity of health outcomes. A mediation analysis was conducted to examine the mediating effects of air pollution on the associations of RH and temperature with health outcomes. We observed that a 1 % increase in the RH was associated with increases in forced expiratory volume in 1 s (FEV₁), eosinophils, and lymphocytes, and a decrease in the total-lobe LAA. A 1 °C increase in temperature was associated with decreases in oxygen desaturation, and right-, left-, and upper-lobe LAA values. Also, a 1 μg/m³ increase in PM_2.5 was associated with a decrease in the FEV₁ and an increase in oxygen desaturation. A 1 μg/m³ increases in PM₁₀ and PM_2.5 was associated with increases in the total-, right-, left, upper-, and lower-lobe (PM_2.5 only) LAA. A one part per billion increase in NO₂ was associated with a decrease in the FEV₁ and an increase in the upper-lobe LAA. Next, we found that NO₂ fully mediated the association between RH and FEV₁. We found PM_2.5 fully mediated associations of temperature with oxygen saturation and total-, right-, left-, and upper-lobe LAA. In conclusion, climate-mediated air pollution increased the risk of decreasing FEV₁ and oxygen saturation and increasing emphysema severity among COPD patients. Climate change-related air pollution is an important public health issue, especially with regards to respiratory disease.

Nanoparticle transport and deposition in a heterogeneous human lung airway tree: An efficient one path model for CFD simulations

Understanding nano-particle inhalation in human lung airways helps targeted drug delivery for treating lung diseases. A wide range of numerical models have been developed to analyse nano-particle transport and deposition (TD) in different parts of airways. However, a precise understanding of nano-particle TD in large-scale airways is still unavailable in the literature. This study developed an efficient one-path numerical model for simulating nano-particle TD in large-scale lung airway models. This first-ever one-path numerical approach simulates airflow and nano-particle TD in generations 0-11 of the human lung, accounting for 93% of the whole airway length. The one-path model enables the simulation of particle TD in many generations of airways with an affordable time. The particle TD of 5 nm, 10 nm and 20 nm particles is simulated at inhalation flow rates for two different physical activities: resting and moderate activity. It is found that particle deposition efficiency of 5 nm particles is 28.94% higher than 20 nm particles because of the higher dispersion capacity. It is further proved that the diffusion mechanism dominates the particle TD in generations 0-11. The deposition efficiency decreases with the increase of generation number irrespective of the flow rate and particle size. The effects of the particle size and flow rate on the escaping rate of each generation are opposite to the corresponding effects on the deposition rate. The quantified deposition and escaping rates at generations 0-11 provide valuable guidelines for drug delivery in human lungs.

Understanding the pathogenesis of occupational coal and silica dust-associated lung disease

Workers in the mining and construction industries are at increased risk of respiratory and other diseases as a result of being exposed to harmful levels of airborne particulate matter (PM) for extended periods of time. While clear links have been established between PM exposure and the development of occupational lung disease, the mechanisms are still poorly understood. A greater understanding of how exposures to different levels and types of PM encountered in mining and construction workplaces affect pathophysiological processes in the airways and lungs and result in different forms of occupational lung disease is urgently required. Such information is needed to inform safe exposure limits and monitoring guidelines for different types of PM and development of biomarkers for earlier disease diagnosis. Suspended particles with a 50% cut-off aerodynamic diameter of 10 µm and 2.5 µm are considered biologically active owing to their ability to bypass the upper respiratory tract's defences and penetrate deep into the lung parenchyma, where they induce potentially irreversible damage, impair lung function and reduce the quality of life. Here we review the current understanding of occupational respiratory diseases, including coal worker pneumoconiosis and silicosis, and how PM exposure may affect pathophysiological responses in the airways and lungs. We also highlight the use of experimental models for better understanding these mechanisms of pathogenesis. We outline the urgency for revised dust control strategies, and the need for evidence-based identification of safe level exposures using clinical and experimental studies to better protect workers' health.

Association between ambient PM2.5 and outpatient visits of children's respiratory diseases in a megacity in Central China

Objective

To explore the relationship between ambient PM_2.5 level and outpatient visits of children with respiratory diseases in a megacity, Zhengzhou, in central China.

Methods

We collected daily outpatient visit data, air pollutant data, and meteorological data at the monitoring points of Zhengzhou from the time period 2018 to 2020 and used Spearman's rank correlation to analyze the correlation between children's respiratory outpatient visits and air pollutants and meteorological factors. Generalized additive models were used to analyze the association between PM_2.5 exposures and children's respiratory outpatient visits. A stratified analysis was further carried out for the seasons.

Results

From 2018 to 2020, the total number of outpatients with children's respiratory diseases was 79,1107, and the annual average concentrations of PM_2.5, PM₁₀, SO₂, NO₂, CO, and O₃-8h in Zhengzhou were respectively 59.48 μg/m³, 111.12 μg/m³, 11.10 μg/m³, 47.77 μg/m³, 0.90 mg/m³ and 108.81 μg/m³. The single-pollutant model showed that the risk of outpatient visits for children with respiratory disease increased by 0.341% (95%CI: 0.274-0.407%), 0.532% (95%CI: 0.455-0.609%) and 0.233% (95%CI: 0.177-0.289%) for every 10 μg/m³ increase in PM_2.5 with a 3-day lag, 1-day lag, and 1-day lag respectively for the whole year, heating period, and non-heating period. The multi-pollutant model showed that the risk of PM_2.5 on children's respiratory disease visits was robust. The excess risk of PM_2.5 on children's respiratory disease visits increased by 0.220% (95%CI: 0.147-0.294%) when SO₂ was adjusted. However, the PM_2.5 effects were stronger during the heating period than during the non-heating period.

Conclusion

The short-term exposure to PM_2.5 was significantly associated with outpatient visits for children's respiratory diseases. It is therefore necessary to strengthen the control of air pollution so as to protect children's health.

A novel in-situ method to determine the respiratory tract deposition of carbonaceous particles reveals dangers of public commuting in highly polluted megacity

Background

Exposure to air pollutants is one of the major environmental health risks faced by populations globally. Information about inhaled particle deposition dose is crucial in establishing the dose–response function for assessing health-related effects due to exposure to air pollution.

Objective

This study aims to quantify the respiratory tract deposition (RTD) of equivalent black carbon (BC) particles in healthy young adults during a real-world commuting scenario, analyze factors affecting RTD of BC, and provide key parameters for the assessment of RTD.

Methods

A novel in situ method was applied to experimentally determine the RTD of BC particles among subjects in the highly polluted megacity of Metro Manila, Philippines. Exposure measurements were made for 40 volunteers during public transport and walking.

Results

The observed BC exposure concentration was up to 17-times higher than in developed regions. The deposition dose rate (DDR) of BC was up to 3 times higher during commute inside a public transport compared to walking (11.6 versus 4.4 μg hr⁻¹, respectively). This is twice higher than reported in similar studies. The average BC mass deposition fraction (DF) was found to be 43 ± 16%, which can in large be described by individual factors and does not depend on gender.

Conclusions

Commuting by open-sided public transport, commonly used in developing regions, poses a significant health risk due to acquiring extremely high doses of carcinogenic traffic-related pollutants. There is an urgent need to drastically update air pollution mitigation strategies for reduction of dangerously high emissions of BC in urban setting in developing regions. The presented mobile measurement set-up to determine respiratory tract deposition dose is a practical and cost-effective tool that can be used to investigate respiratory deposition in challenging environments.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-022-00501-x.

Health risk assessment of particulate matter 2.5 in an academic metallurgy workshop

Exposure to indoor PM_2.5 is associated with allergies, eye and skin irritation, lung cancer, and cardiopulmonary diseases. To control indoor PM_2.5 and protect the health of occupants, exposure and health studies are necessary. In this study, exposure to PM_2.5 released in an academic metallurgy workshop was assessed and a health risk assessment was conducted for male and female students and technicians. Polycarbonate membrane filters and an active pump operating at a flow rate of 2.5 L/min were used to collect PM_2.5 from Monday to Friday for 3 months (August-October 2020) from 08:00-16:00. PM_2.5 mass concentrations were obtained gravimetrically, and the Multiple-Path Particle Dosimetry model was used to predict the deposition, retention, and clearance of PM_2.5 in the respiratory tract system. The risk of developing carcinogenic and non-carcinogenic effects among students and technicians was determined. The average PM_2.5 mass concentration for August was 32.6 μg/m³ 32.8 μg/m³ for September, and 32.2 μg/m³ for October. The head region accounted for the highest deposition fraction (49.02%), followed by the pulmonary (35.75%) and tracheobronchial regions (15.26%). Approximately 0.55 mg of PM_2.5 was still retained in the alveolar region 7 days after exposure. The HQ for male and female students was <1 while that of male and female technicians was >1, suggesting that technicians are at risk of developing non-carcinogenic health effects compared with students. The results showed a risk of developing carcinogenic health effects among male and female technicians (>1 × 10^-5 ); however, there was no excess cancer risk for students (<1 × 10^-6 ). This study highlights the importance of exposure and health studies in academic micro-environments such as metallurgy workshops which are often less researched, and exposure is underestimated. The results also indicated the need to implement control measures to protect the health of the occupants and ensure that the workshop rules are adhered to.

Short-term effects of exposure to ambient PM1, PM2.5, and PM10 on ischemic and hemorrhagic stroke incidence in Shandong Province, China

BACKGROUND

Short-term exposure to ambient PM_2.5 and PM₁₀ is associated with increased risk of mortality and hospital admissions for stroke. However, there is less evidence regarding the effect of exposure to PM₁ on stroke incidence. We estimated the incidence risk of stroke and the attributable fractions related to short-term exposure to ambient PM₁, PM_2.5 and PM₁₀ in China.

METHODS

County-specific incidence of stroke was obtained from health statistics in years 2014-2019. We linked county-level mean daily concentrations of PM₁, PM_2.5 and PM₁₀ with stroke incidence. We used the time stratified case-crossover design to estimate the associations between stroke incidence and exposure to PM₁, PM_2.5 and PM₁₀. We also estimated the disease burden fractions attributable to PM₁, PM_2.5, and PM₁₀.

RESULTS

The study included a total of 2,193,954 stroke, from which 1,861,331 were ischemic and 332,623 were hemorrhagic stroke. PM₁, PM_2.5, and PM₁₀ levels were associated with increased risks of total stroke and ischemic stroke at when assessing the associations in exposure at lag0-4 days. The increase of 10 μg/m³ in PM₁, PM_2.5, and PM₁₀ was associated with total stroke, and the relative risks were 1.012 (95% confidence interval: 1.008, 1.015), 1.006 (1.004, 1.007) and 1.003 (1.002, 1.004), while the associations with ischemic stroke were 1.013 (1.010, 1.017), 1.006 (1.005, 1.008) and 1.003 (1.002, 1.004), respectively. There was no significant association between PM and risk of hemorrhagic stroke. The attributable fractions of total stroke were 6.9% (5.1%, 8.5%), 5.6% (4.2%, 6.8%) and 5.6% (3.9%, 7.1%) for PM₁, PM_2.5, and PM₁₀, respectively.

CONCLUSIONS

PM₁ showed a stronger association with stroke, with a larger attributable fraction of outcomes, than PM_2.5 and PM₁₀. Clean air policies should target the whole scope of PM, including PM₁.

Diurnal and Seasonal Variation of Atmospheric Particulate Matter and Trace Gases in Industrial Area of Delhi: A Study

The diurnal and seasonal variation of PM₁₀, SO₂, NO₂, NH₃ and water-soluble compounds were studied in Naraina industrial area; Delhi from January to December, 2017. It was observed that annual average concentrations of PM_10, SO₂, NO₂, NH_3, SO₄^2-, NO₃^-, NH₄⁺,Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl^- and F^- in the day time were 227 ± 91, 9 ± 5, 59 ± 22, 65 ± 15, 17.45 ± 5.14, 17.60 ± 4.94, 8.66 ± 2.94, 4.05 ± 1.08, 3.46 ± 0.91, 10.38 ± 4.48, 3.15 ± 0.99, 43.06 ± 5.20 and 0.50 ± 0.12 µg m^-3, respectively and night time were 320 ± 127, 14 ± 7, 82 ± 25, 83 ± 20, 22.64 ± 5.22, 21.66 ± 5.0, 11.81 ± 3.47, 3.29 ± 0.87, 3.02 ± 1.19, 7.55 ± 3.16, 2.49 ± 0.95, 31.86 ± 4.70 and 0.37 ± 0.12 µg m^-3, respectively. PM₁₀ and sometimes NO₂ concentrations exceeded the Indian National Ambient Air Quality Standards. SO₂, and NH₃ concentrations were within the standard. The selected parameters varied from season to season. In the night time, selected parameters concentrations were high in comparison to day time might be due to formation of inorganic secondary particulate matters and low wind speed in the ambient air.

Combustion-Derived Particulate PAHs Associated with Small Airway Dysfunction in Elderly Patients with COPD

Evidence of the respiratory effects of ambient organic aerosols (e.g., polycyclic aromatic hydrocarbons, PAHs) among patients with chronic diseases is limited. We aimed to assess whether exposure to ambient particle-bound PAHs could worsen small airway functions in patients with chronic obstructive pulmonary disease (COPD) and elucidate the underlying mechanisms involved. Forty-five COPD patients were recruited with four repeated visits in 2014-2015 in Beijing, China. Parameters of pulmonary function and pulmonary/systemic inflammation and oxidative stress were measured at each visit. Linear mixed-effect models were performed to evaluate the associations between PAHs and measurements. In this study, participants experienced an average PAH level of 61.7 ng/m³. Interquartile range increases in exposure to particulate PAHs at prior up to 7 days were associated with reduced small airway functions, namely, decreases of 17.7-35.5% in forced maximal mid-expiratory flow. Higher levels of particulate PAHs were also associated with heightened lung injury and inflammation and oxidative stress. Stronger overall effects were found for PAHs from traffic emissions and coal burning. Exposure to ambient particulate PAHs was capable of impairing small airway functions in elderly patients with COPD, potentially via inflammation and oxidative stress. These findings highlight the importance of control efforts on organic particulate matter from fossil fuel combustion emissions.