Search Results (248)

Military burn pits used during post-9/11 U.S. military deployments functioned as uncontrolled combustion systems and were widely utilized to dispose of large volumes of outdoor waste by burning. Burn pits involved heterogeneous waste materials burned under variable temperature and oxygen conditions. These combustion environments generated complex, toxic, multipollutant airborne emission mixtures that included particulate matter (PM_2.5), polycyclic aromatic hydrocarbons (PAHs), and volatile organic compounds (VOCs). This narrative review synthesizes epidemiologic, experimental, and mechanistic evidence linking burn pit emissions to disruption of the lung–brain axis and adverse neurological outcomes. We specifically aim to address a critical gap in understanding how combustion-derived toxicants impact brain health and are associated with unfavorable neuropsychiatric outcomes, including increased risk of post-traumatic stress disorder (PTSD) and depression. Combustion-related exposures promote pulmonary inflammation and system-wide immune signaling that propagate to the central nervous system, contributing to neuroinflammation and dysregulation of the hypothalamic–pituitary–adrenal (HPA) axis. These interconnected mechanisms are associated with toxic encephalopathy and related cognitive and mood disturbances, underscoring the need to integrate fire science with military and environmental health services research to better define the systemic and neurological consequences of acute and chronic fire-derived inhalation exposures. Full article

(1) Background: Highway toll plazas are environments impacted by atmospheric pollutants that may affect workers’ health. However, there are still few studies on these environments. This study evaluated particulate matter (PM) concentrations by size fraction (PM_10–9.0 to PM_0.43) and associated arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb) and vanadium (V) at two toll plazas in Brazil. (2) Methods: PM and trace element concentrations were compared between dry and rainy seasons, and a health risk assessment was conducted for toll collectors based on inhalation exposure. (3) Results: PM_10–2.5 concentrations ranged from 31.8 to 360 µg m⁻³ in the dry season and from non-detectable to 287 µg m⁻³ in the rainy season. PM_2.5 levels varied between 14.9 and 150 µg m⁻³ (dry) and 3.46–174 µg m⁻³ (rainy). Although trace element concentrations were within Occupational Safety and Health Administration (OSHA) limits, the hazard quotient (HQ) for manganese and arsenic exceeded unity (HQ > 1), indicating potential health risks. (4) Conclusions: These findings suggest that toll plaza workers may experience increased inhalation-related risk under the exposure assumptions used. Improved ventilation and protective measures, including the use of protective screens, are recommended to reduce occupational exposure. Full article

Fine particulate matter (PM_2.5) exposure in public transport microenvironments has important implications for commuter health, yet concentration-based assessments may not adequately reflect the dose actually inhaled by passengers. This study quantified dynamic PM_2.5 inhaled doses in Taiyuan, China, using 1 Hz portable monitoring and matched travel surveys across 19 bus and metro routes during summer and winter 2025. After data screening, 1103 valid commuter samples were retained. We combined dose estimation with DML, XGBoost-SHAP, SEM, and Random Forest analysis to examine adjusted associations, explore potential nonlinear patterns, and characterize behavioral responses. Trip-averaged PM_2.5 concentrations exceeded the WHO 24 h guideline on most monitored routes when interpreted as a health-based reference benchmark for short commuting exposures rather than as a direct regulatory exceedance metric. More importantly, a clear concentration-dose decoupling pattern was observed: 6.6% of trips fell into a low-concentration but high-dose category, indicating that prolonged in-vehicle exposure could substantially elevate inhaled dose even when PM_2.5 concentrations remained below the sample median. The mean inhaled dose in the longer observed-duration group (top 20% by observed in-vehicle duration) reached 612.26 ± 412.21 μg, which was 7.2 times that of the remaining trips (84.87 ± 115.71 μg). DML results showed that inhaled dose, rather than PM_2.5 concentration alone, was significantly associated with psychological distress. SHAP analysis suggested an exploratory threshold-like pattern at approximately 300 μg per trip, above which health-risk attribution increased rapidly. SEM results indicated that inhaled dose was associated with higher self-reported somatic burden, whereas PM_2.5 concentration mainly influenced health indirectly through risk perception. These findings suggest that public transport exposure assessment should move beyond static concentration metrics and incorporate dynamic inhaled dose to better identify high-risk commuting scenarios and support more targeted health-oriented transit management. Full article

Chronic obstructive pulmonary disease (COPD), which includes chronic bronchitis and emphysema, is highly prevalent worldwide and is the third leading cause of death. While some aspects of the disease were known since the Enlightenment, Laennec’s work in the 19th century began the process of our current understanding of this disease. In this narrative review, 13 clinicians and scientists with over three centuries of cumulative experience treating and studying COPD give their perspectives on the science underpinning our modern concept of this disease and its management. These include (1) the challenges of coming up with a name for what is a complex syndrome; (2) the evolution of our thinking on the natural history of the disease; (3) the importance of particulate matter inhalation in its pathogenesis; (4) the often-overlooked but important—and often treatable—systemic effects of the disease that contribute to its morbidity and mortality; (5) the changes in our perspective of not just addressing pathologic or physiologic abnormalities but also measuring outcomes, such as breathlessness or health-related quality of life, that are of considerable importance to the patient; (6) the role of pharmacologic therapy in not only providing symptomatic relief by increasing airway caliber but also in disease modification, especially by reducing exacerbation frequency; (7) lung hyperinflation as an essential feature of COPD pathophysiology, driving symptom burden, exercise limitation, and mortality risk; (8) long-term oxygen therapy, despite being demonstrated to prolong survival in a defined set of hypoxemic patients with COPD, still having unanswered questions regarding its application and delivery; and (9) pulmonary rehabilitation, a major component of the non-pharmacologic treatment of COPD patients and prominently situated in clinical guidelines for this disease. While this, by necessity, must be a brief review of a very complex disease, the perspectives of these esteemed clinicians and scientists should be of use to other clinicians in understanding and managing this disease. Full article

Farmland particulate pollution seriously affects regional atmospheric quality, and exploring efficient field dust control strategies is an urgent need for agricultural ecological protection. This study employed a wind tunnel and online dust monitoring system to investigate the dust reduction effect of straw return in conservation tillage in Beijing farmland under varying wind speeds and precipitation levels, providing theoretical and technical support for straw coverage configuration and dust pollution control. Given the insufficient understanding of the combined impacts of straw coverage, wind speed and precipitation on farmland particulate emissions, this study examined how these key factors jointly affect fine particulate matter (PM_2.5), inhalable particulate matter (PM₁₀), and total suspended particulate (TSP) emissions. A three-factor, three-level response surface experiment modeled these relationships and identified optimal conditions for suppressing PM emissions—51.35% straw coverage, 3.96 m·s⁻¹ wind speed, and 32.36 mm precipitation—yielding average PM_2.5, PM₁₀, and TSP concentrations of 26.31, 31.71, and 42.43 μg·m⁻³, respectively. Field data showed that the mean absolute errors (MAEs) between predicted and measured concentrations were 0.52–5.80, 0.46–3.93, and 1.83–5.68 μg·m⁻³ for PM_2.5, PM₁₀, and TSP, respectively, corresponding to relative prediction accuracies of 90.42–97.95%, 95.03–98.52%, and 93.10–97.21%—indicating strong model accuracy. This approach enhances dynamic monitoring of straw return practices and guides rational field management. By integrating meteorological conditions and particulate emission characteristics, the model can quantitatively assess regional straw coverage and screen optimal straw mulching rates. It provides a clear data reference for decision-makers to formulate targeted dust prevention policies, standardize straw return regulation, and advance eco-friendly and sustainable agricultural production. Full article

Atmospheric arsenic (As) poses significant health threats in heavily polluted urban environments. However, the size-resolved distribution of water-soluble arsenic (WSAs) in atmospheric particulate matter, as well as the size-dependent variation in As concentration and solubility under contrasting haze and non-haze conditions, remains insufficiently characterized. This study investigated the concentration, size distribution, water solubility, sources, and health risks of particulate-bound As and WSAs in Beijing from April 2014 to February 2015. The annual mean PM_0.1–18 concentration was 136.96 ± 54.21 μg·m⁻³, with significantly higher levels observed during haze episodes (179.61 ± 41.71 μg·m⁻³) compared to non-haze periods (118.00 ± 49.42 μg·m⁻³). The annual mean concentration of As was 6.42 ± 3.69 ng·m⁻³, exceeding both WHO guidelines and Chinese standards during haze periods, while WSAs averaged 4.54 ± 2.50 ng·m⁻³. Distinct size distribution patterns were observed: As displayed, a unimodal fine-mode peak (0.32–0.56 μm) was observed during haze periods and a bimodal distribution during non-haze conditions, whereas WSAs followed comparable size-dependent behavior, reflecting shifts in dominant emission sources and atmospheric processes. The average WSAs/As ratio (0.72 ± 0.07) indicated high As solubility and strong associations with secondary species and anthropogenic emissions. Size-resolved analysis revealed that As was preferentially enriched in fine particles, particularly during haze episodes, whereas coarse particles became more prominent under non-haze conditions, especially in spring, likely driven by regional dust transport and its interactions with anthropogenic emissions. Deposition modeling based on the ICRP framework showed that As and WSAs were primarily deposited in the headway (HA: 0.68 and 0.32 ng·h⁻¹, respectively), followed by the alveolar region (AR: 0.29 and 0.20 ng·h⁻¹, respectively). Fine particles enhanced deposition in deeper lung regions during haze episodes, whereas coarse particles contributed more to upper airway deposition under non-haze conditions. Although inhalation carcinogenic risks remained within acceptable limits (10⁻⁶–10⁻⁴), risks were 1.60 times higher during haze periods, with adults bearing the greatest exposure burden. These findings demonstrate that haze conditions substantially alter the size distribution, solubility, and health risks of atmospheric arsenic, and provide a scientific basis for developing size-resolved and haze-targeted heavy metal monitoring strategies in urban environments subject to significant anthropogenic pollution. Full article

(1) Airborne fine particulate matter (PM_2.5) poses a growing threat to poultry production by impairing intestinal health, disturbing microbial balance, and reducing growth performance. Rosmarinic acid (RA), a natural polyphenol with antioxidant, anti-inflammatory, and gut microbiota-regulating properties, can effectively maintain intestinal homeostasis. To date, its protective effects against PM_2.5-induced intestinal injury in broilers remain largely unclear. This study investigated whether dietary RA supplementation mitigates intestinal damage and microbiota dysbiosis caused by PM_2.5 in broilers and explored the related mechanisms. (2) A total of 144 21-day-old broilers were randomly allocated to three groups, control (CON), PM_2.5 exposure (PM), and PM_2.5 exposure plus rosmarinic acid (RA), with six replicates of eight broilers each. (3) Results indicated that PM_2.5 exposure severely impaired growth performance, whereas dietary RA significantly increased average daily feed intake and average daily gain, decreased the feed-to-gain ratio, and elevated final body weight in broilers. RA significantly attenuated PM_2.5-induced intestinal inflammation, as evidenced by reduced expression of inflammatory cytokines (IL-6 and IFN-γ) and downregulation of key components in the TLR4 signaling pathway (TLR4, MyD88, and NF-κB). Inhaled PM_2.5 exposure impaired the intestinal epithelial barrier, marked by decreased mRNA levels of MUC2 and CLDN1 and increased caspase3 expression. Dietary RA treatment effectively restored these indicators, suggesting its role in maintaining epithelial integrity. Furthermore, RA reshaped the gut microbiota structure, altering both α- and β-diversity. Notably, RA led to a higher proportion of potentially health-promoting bacterial taxa, including Lactobacillus, V9D2013_group, and Oscillospirales, while reducing opportunistic pathogens like Shuttleworthia. (4) In conclusion, RA alleviates PM_2.5-induced intestinal inflammation, reinforces the epithelial barrier, and modulates the intestinal microbiota in broilers, likely through inhibition of the TLR4/NF-κB signaling. These findings reveal a novel mechanism by which RA mitigates pollutant-induced intestinal injury via gut microbiota modulation and TLR4/NF-κB suppression, offering new insights into the gut–lung axis in avian species. Full article

Air pollution associated with public transport systems constitutes a critical yet highly heterogeneous component of urban exposure and represents an important challenge for sustainable urban mobility and environmental health governance. Commuters and transport workers are frequently subjected to pollutant concentrations that exceed those reported by ambient background monitoring networks. This review provides a comprehensive synthesis of the global scientific literature on air quality in public transport microenvironments—including buses, bus stops, terminals, and underground stations—through a multidimensional analytical framework that considers climatic classification, socio-economic context, meteorological drivers, transport microenvironment typology, sampling strategies, analytical techniques, and exposure metrics. A large body of peer-reviewed studies published worldwide was examined to identify dominant patterns, methodological trends, and persistent knowledge gaps. Across regions, the evidence consistently reports elevated concentrations of particulate matter (PM_2.5, PM₁₀, and ultrafine particles) and traffic-related gaseous pollutants, particularly within confined or poorly ventilated environments and during peak traffic periods. Marked geographical, climatic, and socio-economic imbalances are evident, with most studies conducted in temperate and tropical climates and in countries with very high or high Human Development Index, whereas arid, continental, and low-HDI regions remain substantially underrepresented. From a methodological perspective, the literature is dominated by short- to intermediate-term monitoring campaigns relying on active sampling, mobile measurements, and increasingly calibrated low-cost sensors, while long-term stationary observations and standardized integrative monitoring frameworks remain scarce. Although advanced analytical approaches—such as chemical characterization, environmental magnetism, receptor modeling, computational fluid dynamics, and inhaled dose assessment—are increasingly applied, their systematic integration remains limited. Overall, this review reveals persistent methodological, geographical, and conceptual gaps and highlights the urgent need for standardized, interdisciplinary, and long-term monitoring strategies to improve exposure assessment and support evidence-based mitigation policies and sustainable urban transport planning aimed at reducing health risks associated with public transport-related air pollution. Full article

Traffic-related emissions significantly contribute to fine particulate matter (PM_2.5) in urban roadside environments, where limited dispersion elevates human exposure and health risks. This study provides an integrated assessment of PM_2.5 exposure in a traffic-dominated roadside microenvironment in Jaipur, India, and evaluates seasonal variability, respiratory deposition dose (RDD), elemental composition, source characteristics, and inhalation health risk. Ambient PM_2.5 sampling was performed from October to February, and gravimetric and elemental analyses were conducted. RDD was quantified, and non-carcinogenic and carcinogenic risks were estimated using USEPA guidelines. PM_2.5 concentrations showed strong seasonal variability, peaking at 97 ± 5.85 µg/m³ during low-temperature winter weekdays, exceeding national and World Health Organization guidelines by 1.6 and 6.5 times, respectively. Winter conditions also led to higher RDD (~80% deposition in the head region) and the enrichment of traffic-related metals, particularly chromium, cadmium, and lead. Backward trajectory analysis indicated dominant local traffic influence with episodic regional transport. Non-carcinogenic risk surpassed unity for children during winters, while carcinogenic risk, primarily driven by chromium, exceeded acceptable thresholds (1 × 10⁻⁶), reaching 610 times higher during low-temperature winter weekdays. This first integrated PM_2.5 health risk assessment for Jaipur underscores the need of dose- and composition-based assessment in traffic-influenced urban environments. Full article

Driven by rapid global urbanization and expanding urban footprints, air pollution, particularly from industrial emissions and vehicular exhaust, has intensified, with rising concentrations of inhalable particulate matter (PM) posing direct threats to public health. To address this challenge, we conducted field measurements of ambient PM concentrations across diverse urban plant communities and quantitatively compared their capacity to mitigate four key size-fractionated pollutants: total suspended particles (TSPs), PM₁₀, PM_2.5, and PM₁. Our objective was to identify the most effective plant community type for PM abatement in urban settings. Results demonstrate that: (1) evergreen broad-leaved forests exhibit the highest overall PM removal efficiency among all studied communities; (2) removal efficacy declines markedly with decreasing particle size, indicating limited capacity to capture ultrafine particles (e.g., PM₁); and (3) seasonal performance peaks in summer, especially for deciduous broad-leaved forests attributable to maximal leaf area index, enhanced stomatal activity, and favorable meteorological conditions. By rigorously evaluating species composition, canopy structure, and seasonal dynamics, this study provides empirically grounded guidance for evidence-based urban greening strategies aimed at optimizing airborne particulate mitigation worldwide. Full article

The concentration of heavy metals in the environment has been steadily increasing, raising concerns about their adverse effects on ecosystems and human health. Fine-grained particulate matter is of particular concern due to its enhanced mobility, bioavailability, and potential for inhalation exposure. Facilities involved in the mechanical processing of electronic waste (e-waste) represent a significant potential source of metal-containing fine particles. In this study, crushed e-waste components containing precious metals were separated into particle-size fractions ranging from 3.0 to 0.15 mm using a vibratory sieving system. The elemental composition of the individual fractions was determined by energy-dispersive X-ray fluorescence spectrometry (ED-XRF), while the spatial distribution of selected metals in fine fractions was further investigated using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM–EDS). The results demonstrate that e-waste contains a wide range of heavy non-ferrous metals whose distribution is strongly dependent on particle size. A pronounced enrichment of metals was observed in the finest fractions, particularly below 0.25 mm. Compared to the coarse fraction (>3 mm), the zinc concentration increased by approximately one order of magnitude, while chromium, nickel, and cadmium exhibited increases of up to approximately 20-fold. Lead showed particularly high enrichment, reaching approximately 2 wt.% in the finest fraction (<0.15 mm), corresponding to nearly fiftyfold enrichment relative to the coarse fraction. Tin concentrations also increased markedly, in some cases by up to two orders of magnitude. Trace amounts of arsenic and selenium were detected in the finest fractions, whereas mercury was not detected. The combined ED-XRF and SEM–EDS results confirm that fine-grained e-waste fractions are the dominant carriers of hazardous metals and respirable particles generated during mechanical processing. These findings highlight the dual character of fine fractions as both a critical environmental and occupational risk and a potentially valuable secondary resource. The study emphasizes the importance of controlled handling, effective dust management, and targeted processing strategies to minimize human exposure while enabling efficient recovery of valuable metals from e-waste. Full article

Iron oxide particles (magnetite Fe₃O₄, hematite α-Fe₂O₃, and maghemite γ-Fe₂O₃) are prevalent constituents of atmospheric particulate matter (PM) and have gained increasing attention due to potential health implications. This scoping review provides a broad mapping of published in vivo and in vitro studies addressing the biological and toxicological effects of iron oxide particles across particle size fractions (PM10, PM2.5, PM1.0, and nanoscale) and exposure routes, including inhalation, intranasal instillation, and intravenous administration. As a scoping review, no formal risk-of-bias appraisal was conducted; however, studies were selected through predefined eligibility criteria and a structured screening workflow. Iron oxide exposure is consistently associated with oxidative stress and inflammatory responses, while mitochondrial dysfunction, genotoxicity, and neurological effects are frequently reported depending on particle characteristics and exposure context. Among studies with explicit crystalline phase identification, magnetite is most frequently associated with higher biological reactivity, whereas hematite and maghemite display more variable and context-dependent responses. Limited human evidence aligns with experimental findings, identifying magnetite-rich nanoparticles in neural and cardiovascular tissues alongside markers of oxidative and mitochondrial damage. Overall, this scoping review highlights dominant research trends, mechanistic pathways, and key knowledge gaps regarding iron oxide-containing PM, emphasizing the need for integrative approaches linking atmospheric particle characterization with toxicological research. Full article

Industrial coastal basins that host heavy industry can concentrate metal-bearing dust in school environments. We performed a screening multi-matrix assessment across six schools in Quintero–Puchuncaví (central Chile). We measured As, Cd, Cr, Cu, Ni, Pb, and Mn in surface soils (winter 2023; E1–E4 only), indoor settled dust, and settleable particulate matter (SPM) collected in winter (July 2023) and summer (November 2023). Concentrations were determined by ICP-OES/ICP-MS and interpreted with enrichment factors and the geoaccumulation index. A U.S. EPA screening framework was used to estimate non-carcinogenic hazard (HQ) and incremental lifetime cancer risk (ILCR) for ingestion, inhalation, and dermal contact, as well as cumulative indices for non-carcinogenic (HI) and carcinogenic risk (Risk). SPM carried the strongest anthropogenic signal (EF up to 9900 for Cd, 408 for Cu, and 143 for Pb) and the highest summer loads (Cu > 5000 mg kg⁻¹; Ni > 1000 mg kg⁻¹). Cu dominated non-carcinogenic hazard (HQ up to 137), whereas ILCR was driven by Ni, As, and Cr, exceeding 10⁻⁴ and reaching 10⁻³ at inland/valley schools in summer. Indoor dust showed intermediate burdens, indicating indoor accumulation of outdoor-derived metals, while the winter soil survey provides a baseline indication of outdoor metal reservoirs at the sampled schools. Despite the limited sample size, the results provide screening-level evidence to inform emission control and dust mitigation in school microenvironments. Full article

Background: Particulate matter (PM_2.5) inhalation induces pulmonary disorders through oxidative stress. Veratramine (VRT), a steroidal alkaloid derived from Veratrum species, exhibits protective pharmacological potential. Therefore, this study aims to investigate the protective effects of VRT against PM_2.5-induced oxidative injury and the underlying molecular mechanisms. Methods: In vitro experiments were conducted using pulmonary artery endothelial cells (HPAECs), which were exposed to PM_2.5 (25–100 μg/mL) ± VRT (2–50 μM) or Dexamethasone (DEX; 50 μM) for 24–48 h. Measurements included 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide viability, Lactate dehydrogenase ELISA, 2′,7′-dichlorodihydrofluorescein diacetate reactive oxygen species (ROS), superoxide dismutase/catalase kits, and Western blots (Bax, serum, and glucocorticoid-regulated kinase 1 (SGK1), microtubule-associated protein 1 light chain 3 (LC3), Toll-like receptor (TLR4), and mechanistic target of rapamycin (mTOR)). Results: PM_2.5 exposure reduced HPAEC viability in a dose- and time-dependent manner, likely due to increased lactate dehydrogenase leakage and intracellular ROS accumulation. Oxidative stress correlated with altered superoxide dismutase and catalase activities, with suppression of SGK1, a key factor in cell survival. VRT treatment enhanced cell viability, mitigated oxidative stress, and restored SGK1 expression. Moreover, VRT promoted mTOR phosphorylation and markedly suppressed PM_2.5-induced increases in TLR4, MyD88, and the autophagy markers LC3 II and Beclin 1. Conclusions: Collectively, these findings indicate that VRT protects against PM_2.5-induced pulmonary injury by modulating oxidative stress and the mTOR-associated autophagy pathway, highlighting its potential as a therapeutic candidate for PM_2.5-related respiratory disorders. Full article

Although particulate matter has been associated with sleep problems, the effects of PM_2.5-bound organophosphate esters (OPEs) on children’s sleep remain unclear. OPEs have neurotoxic and endocrine-disrupting effects that may disrupt sleep–wake regulation during neurodevelopment, supporting biological plausibility for sleep impacts. In this study, we quantified the individual and mixture effects of PM_2.5-bound OPEs on the sleep disorder domain. This cross-sectional study included 110,169 children aged 6–18 years from primary and secondary schools in the Pearl River Delta (PRD), China. Sleep disorders were evaluated using the validated Sleep Disturbance Scale for Children (SDSC). Elastic net and mixed effect models identified specific OPE–sleep associations, while weighted quantile sum regression evaluated mixture effects. All odds ratios indicate a change in the likelihood of sleep disorders per interquartile range (IQR) increase in OPE concentrations. The strongest individual associations were observed for TDCIPP with short sleep duration (OR = 1.56–1.61; moderate association), TEHP with short sleep duration (OR = 1.59–1.64; moderate association), and TPHP with overall sleep disorder (OR = 1.32–1.42; modest association). Combined OPE exposure was positively associated with all sleep disorder domains (ORs = 2.02–2.85; moderate-to-large associations). These results indicate that inhaling PM_2.5-bound OPE mixtures could negatively impact children’s sleep health. This emphasizes a critical developmental period and highlights the importance of public health concerns related to emerging airborne contaminants. Full article