Search Results (2,625)

Nighttime light (NTL), a crucial indicator of human activity intensity, has not been systematically analyzed for its interactive mechanisms with air pollution and climate change. This study first investigates the spatiotemporal evolution of China’s total nighttime light (TNTL) and average nighttime light (ANTL), alongside key indicators of meteorological parameters and air pollution, at the grid scale from 2000 to 2023. We then employ prefecture-level city data and a geographically and temporally weighted regression (GTWR) model to quantify the spatiotemporally heterogeneous associations of temperature (TMP), precipitation (PRE), fine particulate matter (PM_2.5), ozone (O₃), land use (LUL), topography, and socioeconomic factors with NTL. The results indicate that (1) China’s NTL exhibits a significant overall upward trend, with areas of increase or significant increase comprising 92.04% of the total study area. TNTL growth demonstrates regional heterogeneity, expanding by a factor of 4.91 in East China and 2.65 in Northeast China; (2) meteorological and air pollution indicators display spatiotemporal non-stationarity, with the synergistic effect between O₃ and PRE being the strongest; (3) among NTL drivers, LUL contributes most significantly (0.44), followed by TMP (0.14) > PM_2.5 (−0.33 × 10⁻¹) > O₃ (0.17 × 10⁻¹) > PRE (−0.33 × 10⁻⁶); (4) TMP and PRE may primarily influence NTL by altering ecological conditions and nighttime activity patterns. TMP shows a strong positive correlation with NTL in the junction zone of South, East, and Central China, whereas PRE predominantly exerts a negative influence; (5) air pollution exhibits distinct spatiotemporal effects: high PM_2.5 and O₃ generally correspond to lower NTL, though positive correlations persist in some areas due to industrial structures, highlighting the need for integrated policies that balance air quality management with sustainable urban planning; (6) the 2013 “Air Pollution Prevention and Control Action Plan” significantly strengthened the negative correlation between PM_2.5 and NTL in North China. However, O₃ concentrations increased by 28.9% after 2017, underscoring the challenge of coordinating VOC and NOx controls for long-term atmospheric sustainability. 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

Myo-inositol (MI) is recognized as a potential stress regulator capable of alleviating abiotic stress. The objective of this study is to analyze the role of MI in the salt stress response of Daucus carota L. and its potential mechanisms. “Hongxin Qicun” carrot seedlings were subjected to five treatments: control; salt stress (50 mM NaCl); and salt stress combined with 50, 100, or 200 μM of MI. Through an integrated approach combining physiological assays, non-invasive micro-test technology (NMT), and gene expression profiling, we found that salt stress severely inhibited seedling growth, disrupted K⁺/Na⁺ homeostasis, and triggered excessive H₂O₂ accumulation. Exogenous MI application mitigated these salt-induced damages, with 100 μM MI exerting the optimal effect. MI enhanced Na⁺ efflux and reduced K⁺ efflux in carrot roots under salt stress. Inhibitor experiments indicated that MI-promoted Na⁺ efflux relies on active transport via the plasma membrane (PM) Na⁺/H⁺ antiporter system, and qRT-PCR analysis showed that this response was accompanied by the upregulation of DcSOS1. Furthermore, MI contributes to K⁺ homeostasis by synergistically modulating PM H⁺-ATPase and high-affinity potassium transporters. The established proton gradient helps reduce salt-induced K⁺ loss through depolarization-activated potassium channels and non-selective cation channels. MI treatment decreased electrolyte leakage, malondialdehyde content, and H₂O₂ accumulation by enhancing the activities of the plant antioxidant defense system. Meanwhile, MI upregulated the expression of myo-inositol oxygenase (DcMIOXs) genes, which may contribute to osmotic balance maintenance and facilitate ROS scavenging. In conclusion, exogenous MI alleviates salt-induced physiological disorders in Daucus carota L. by coordinately regulating K⁺/Na⁺ and ROS homeostasis, with 100 μM identified as the optimal concentration for this effect. Full article

The Chengdu–Chongqing Twin-City Economic Circle (CC-TCEC), located in the Sichuan Basin, frequently experiences persistent winter PM_2.5 pollution due to basin-constrained ventilation and strong meteorology–emission coupling. Using daily PM_2.5 observations from 113 monitoring stations with a strict two-year training and one-year testing split, we develop hybrid spatiotemporal forecasting models that couple a graph neural network (GCN/GAT) for inter-station spatial dependence learning with a temporal backbone (LSTM/Transformer) for evolving concentration dynamics. We adopt a rolling one-day-ahead forecasting scheme using a 7-day look-back window. Across 12-month, 6-month, and 3-month evaluation windows, the meteorology-augmented Multi-GAT-Transformer shows a slight but consistent advantage over the other tested variants, suggesting potential benefits of attention-based spatial weighting and long-range temporal self-attention under nonstationary basin pollution regimes. Spatiotemporal mappings derived from the best-performing configuration suggest that elevated winter PM_2.5 is mainly associated with low-lying areas such as the Chengdu Plain, industry clusters, and dense urban cores, with peaks that also coincide with the New Year and the pre-Lunar New Year period, suggesting a possible contribution from elevated traffic and production activity. These impacts are amplified by winter stagnation (low winds, high humidity, limited precipitation). From a policy perspective, the results support sustainability-oriented winter haze management by enabling early episode warning and hotspot prioritization. Full article

Hourly concentrations of PM_2.5-bound elements were continuously monitored in Windsor, Canada, from April 2021 to April 2023. Health risk assessment methods of the USEPA were utilized to quantify lifetime cumulative cancer risks (CRs) using six PM_2.5-bound elements, and chronic non-cancer hazard quotients (HQs) using 11 elements, for each season, each source factor, and each hour of day. The two-year average PM_2.5 mass concentration was 9.2 μg/m³, slightly exceeding Ontario’s Ambient Air Quality Criteria of 8.8 μg/m³. A discernible diurnal concentration pattern was noted for most elements, peaking during morning rush hours and tapering during the daytime, largely attributed to local human activities and changes in atmospheric mixing heights. Despite this, both the total lifetime cumulative CR (4.1 × 10⁻⁵) and non-cancer total HQ (0.82) from exposure to ambient elements remained below the corresponding USEPA-acceptable levels. The seasonal variation in CRs and HQs was minimal. However, the diurnal variation was strong, with higher risks during morning rush hours (6:00–8:00) when traffic volume peaks, and lower risks during the daytime (12:00–20:00) when atmospheric mixing height is enhanced. Metal processing emerged as the most significant contributor to the total CR (52%) and HQ (60%), followed by coal/heavy oil burning (19% and 16%, respectively), and vehicular exhaust (19% and 12%, respectively). The remaining two source factors accounted for 10% of CR and 12% of HQ. Cd (62%) was the largest contributor to CRs, followed by Cr(VI) (25%), Co (6%), As (5%), Ni (2%), and Pb (<0.1%). Similarly, Cd dominated HQs (73%), followed by Mn (11%), Ni (6.3%), with the remaining eight elements collectively contributing 9.7%. Although levels of CRs and HQs are low, efforts to mitigate ambient Cd emissions from metal processing sources will help reduce exposure and protect the environment and human health, given Cd is the primary contributor to the total CR and HQ during the study period. Full article

(1) Research Highlights: This study provides the first integrated assessment of Scots pine (Pinus sylvestris L.) growing in the urban forests of Karaganda, Kazakhstan, a city consistently ranked among the most air-polluted cities globally. We examined the adaptive phyto-chemical response of needles to extreme technogenic stress and evaluated their dual potential as biological filters and renewable sources of bioactive compounds. (2) Background and Objectives: Urban forests are critical for mitigating air pollution; however, the biochemical responses of trees in heavily industrialized environments remain poorly understood. Karaganda faces severe atmospheric pollution from mining, metallurgy, and energy sectors, with particulate matter (PM) levels exceeding permissible limits by up to 20-fold. This study aimed to evaluate the state of Pinus sylvestris, a key component of local protective plantations, by studying heavy metal accumulation, anatomical localization of secondary metabolites, and the phytochemical profile and biological activity of needle extracts obtained using different extraction techniques. (3) Materials and Methods: Needles were collected from 15 trees across three sites in Karaganda’s industrial green zones. Heavy metal content (Pb, Cd, As, and Hg) was determined using atomic absorption spectroscopy and voltammetry. Anatomical–histochemical analysis localizes major metabolite classes. Liquid extracts were prepared using four methods, percolation (PER), vortex-assisted (VAE), microwave-assisted (MAE), and ultrasound-assisted (UAE) extraction, and analyzed by GC-MS. Antimicrobial activity was tested against S. aureus, B. subtilis, E. coli, and C. albicans using the disk diffusion method. The antioxidant capacity (water- and fat-soluble) was measured amperometrically. Statistical analysis was performed using one-way ANOVA with Tukey’s HSD test (p < 0.05). Results: Despite extreme ambient pollution, heavy metal concentrations remained below pharmacopoeial limits (Pb < 0.1, Cd < 0.05, As < 0.01, Hg < 0.001 mg/kg), indicating effective biofiltration without toxic accumulation. Histochemistry confirmed the active synthesis of protective phenolics, flavonoids, and essential oils in the mesophyll, epidermis, and schizogenic cavities. GC-MS identified 72 compounds in the PER extract, 70 (the VAE), 72 in (MAE), and 46 in (UAE). The PER extract exhibited the highest relative abundance of bioactive terpenoids: α-cadinol (5.24%), α-muurolene (4.32%), and caryo-phyllene (2.20%). UAE extracts exhibited elevated 5-hydroxymethylfurfural (6.90%), indicating degradation. Antimicrobial testing revealed that PER produced the largest inhibition zone against S. aureus (15.0 ± 1.0 mm), significantly exceeding that of the other methods (p < 0.001). PER extract also demonstrated the highest water-soluble antioxidant capacity (3600 ± 0.40 mg quercetin equiv./dm³) and substantial fat-soluble activity (1633 ± 0.23 mg gallic acid equiv./dm³). (4) Conclusions: Pinus sylvestris in Karaganda exhibits remarkable adaptive resilience, maintaining safe heavy metal levels while accumulating a rich repertoire of stress-induced secondary metabolites. Classical percolation optimally preserves this native phytocomplex, yielding extracts with superior antimicrobial and antioxidant properties. These findings support a dual-use model wherein urban pine plantations simultaneously serve as living biofilters and renewable sources of standardized bioactive extracts, a concept with direct implications for circular bioeconomy strategies in industrial regions worldwide. This supports the strategic importance of coniferous plantations for bioremediation and sustainable resource use in industrial regions. Full article

Urban air quality is a key component of environmental sustainability and public health in large metropolitan areas. Following the substantial but temporary improvements in air quality observed during the COVID-19 lockdowns, it remains unclear whether structural changes in urban air pollution have persisted in the post-pandemic period. This study analyzes the temporal dynamics of major atmospheric pollutants in Mexico City between 2021 and 2024, including CO, NO₂, NO_x, O₃, PM₁₀, PM_2.5, and SO₂, using hourly data from the Mexico City Atmospheric Monitoring System (SIMAT). Annual and monthly median concentrations were computed to reduce the influence of extreme values and short-term pollution episodes. Station-level monotonic trends were evaluated using the non-parametric Mann–Kendall test, complemented by the use of Sen’s slope estimator to quantify the magnitude and direction of change. Absolute and relative changes between 2021 and 2024 were also analyzed to capture incremental variations not reflected by trend significance tests and performed together with hourly monthly analyses to characterize diurnal and seasonal patterns. Results indicate that no statistically significant monotonic trends were detected for any pollutant across the analyzed stations (p > 0.05), suggesting an overall stabilization of air quality levels during the post-pandemic period. Nevertheless, moderate increases in annual median concentrations were observed at specific locations, particularly for PM₁₀, PM_2.5, NO₂, and NO_x, with relative changes ranging from approximately 5% to 35%. Persistent diurnal and seasonal patterns were identified, closely associated with traffic activity, photochemical processes, and meteorological conditions. These findings suggest that, although no robust long-term trends are evident, incremental increases and stable temporal structures remain relevant from a sustainability perspective. Continued monitoring and targeted air quality management strategies are therefore necessary to support long-term urban environmental sustainability. Full article

Crop residue open burning is a major source of atmospheric pollutants that degrade regional air quality, enhance climate forcing, and threaten public health through emissions of particulate matter, greenhouse gases, and toxic species. In southern China, satellite-based emission estimates are often underestimated because frequent cloud cover and limited spatiotemporal resolution hinder the detection of agricultural fires. In this study, crop residue open burning emissions in Guangxi province from 2017 to 2023 were quantified using a statistical approach. The open burning proportion (OBP) was updated on an annual basis using the Visible Infrared Imaging Radiometer Suite (VIIRS) 375 m active fire product (VNP14IMG), and recently reported emission factors (EF_S) were adopted to enhance estimation accuracy. Annual emissions of pollutants were then spatially distributed to 0.05° × 0.05° grid cells based on satellite-detected fire counts and land cover information. The results indicated the total emissions of black carbon (BC), organic carbon (OC), sulfur dioxide (SO₂), nitric oxide (NO_X), carbon monoxide (CO), carbon dioxide (CO₂), fine particles (PM_2.5), coarse particles (PM₁₀), ammonia (NH₃), methane (CH₄) and non-methane volatile organic compound (NMVOC) in Guangxi province during 2017–2023 were 58.90, 230.48, 37.90, 213.95, 4234.41, 108,775.48, 583.09, 667.70, 46.36, 322.74 and 710.20 Gg, respectively. Sugarcane residue burning was identified as the dominant contributor, accounting for 41.26–64.38% of total emissions, followed by rice (20.66–43.06%), corn (5.11–17.25%), and cassava (4.33–6.45%). Emissions exhibited clear interannual variability, declining from 2017 to 2020 under strict control measures and increasing again from 2021 to 2023 as enforcement weakened. Incorporating annually updated VIIRS-derived OBP_S into the statistical inventory improves the temporal representation and reliability of multi-year emission estimates for agricultural burning. Full article

This paper presents the synthesis, physicochemical characterisation, and analytical applications of chemiluminescent (CL) labels based on acridinium salts (ALs) for biomedical diagnostics. These compounds emit light as a result of oxidative reactions and represent an established class of reagents widely employed in chemiluminescence immunochemical assays (CLIAs) today. A series of structurally differentiated acridinium labels (AL1–AL5) was synthesised applying mostly original synthetic routes and purified to chromatographic purity (>90%, RP-HPLC). The compounds, including a commercial product treated as a reference, were successfully conjugated to anti-human IgG, yielding stable immunochemical reagents suitable for immunoassays with CL detection. The chemiluminescence properties of the obtained labels and their protein conjugates were investigated in aqueous buffers and in the presence of surfactants. The emission profiles exhibited characteristic flash-type kinetics with emission maxima occurring within 0.15–0.25 s after reaction initiation. The presence of surfactants more or less significantly enhanced the emission intensity, with signal increases of up to approx. 2-fold compared to surfactant-free systems. Analytical calibration demonstrated a linear response of signal derived from native labels over at least one order of magnitude of concentration, with detection limits falling in the range of 10⁻⁹–10⁻¹⁰ M, confirming the high sensitivity of the developed compounds. The experimental results were supported by theoretical studies using density functional theory (DFT), which confirmed the energetic feasibility of the CL reaction pathway and identified structural factors influencing activation barriers. Additional semiempirical calculations (PM7) indicated that the dielectric environment and proximity of ionic species can influence the reaction energetics, providing mechanistic support for the experimentally observed effects of surfactants. The results demonstrate that both molecular structure and microenvironment influence CL efficiency and kinetics of the investigated systems. The developed acridinium labels exhibit analytical performance better or comparable to commercial reagents and are fully compatible with standard immunodiagnostic conjugation protocols, confirming their suitability for use in modern chemiluminescent immunoassays. Full article

Background: Physical activity is widely acknowledged as an effective intervention for alleviating premenstrual syndrome (PMS) symptoms. However, the optimal exercise dosage that provides symptom relief without increasing the risk of sports-related injuries remains unclear, particularly in adolescent females. Objectives: This study investigates the epidemiology of PMS and sports injuries among national-level adolescent female badminton athletes to inform training practices that balance symptom relief and injury prevention. Methods: A total of 63 national-level adolescent female badminton players aged 13–18 completed questionnaires assessing medical history related to badminton, premenstrual symptoms (PSQ), and menstrual health. All participants were adolescent females who had experienced menarche. Data were analyzed to identify associations between training parameters, PMS symptoms, and injury prevalence. Results: The analysis showed that 13.8% of female badminton athletes experienced knee and lumbar injury associated with badminton participation. The peak incidence of knee injuries occurred at the age of 15, whereas the age of 17 was a peak period for lumbar injuries. A total of 47 (74.6%) athletes experienced at least one premenstrual symptom. The most common symptoms were anger/irritability and anxiety/tension. The players with premenstrual syndrome showed significantly increased menses time (OR: 1.16, p < 0.05), menstrual days in the past 12 months (OR: 4.06, p < 0.05), and badminton experience period compared with those without (OR: 1.441, p < 0.05). Conclusions: PMS symptoms and sports-related injuries are prevalent among national-level adolescent female badminton athletes. Longer participation history in badminton was associated with a higher prevalence of PMS symptoms. These findings underscore the importance of considering menstrual health alongside injury prevention in the training and health management of adolescent female athletes. Further studies using objective training exposure and clinical assessments are warranted. Full article

The objective of this study was to use plant models, Allium cepa and Lepidium sativum, to assess the genotoxic effects of the urban particulate matter (PM) collected in a Northern Italian town. Aqueous extracts of different particle sizes (PM_10–3, PM_3–0.5, PM_0.5) were tested alongside the organic extracts through the standard Ames test. The organic particulate matter extracts were subjected to mutagenicity testing in the Salmonella typhimurium strains TA98 and TA100 (without and with metabolic activation), whereas the aqueous extracts were evaluated for genotoxicity in the emerging seedlings of L. sativum and in the root tips of A. cepa bulbs using the comet test to detect the primary DNA damage. Furthermore, the micronuclei frequency was assessed in the bulbs of A. cepa. As expected, the organic extracts of PM_3–0.5 and PM_0.5 induced point mutations in bacteria. The aqueous extracts of the finest fractions caused a significant increase in genotoxic damage in both plant models. These findings indicate that the two plant models (L. sativum seeds and A. cepa bulbs) are able to detect the genotoxicity of aqueous extracts of air pollutants, with many potential advantages as screening-level tools to complement Ames testing for an easier assessment of urban air quality in terms of DNA toxicity. Full article

The low-carbon city pilot (LCCP) and carbon emissions trading (CET) represent two critical policies for reducing carbon emissions. Accurately evaluating their synergistic effects on the reduction in pollution and carbon emissions (RPCE) is of utmost importance for advancing China’s low-carbon economic growth and achieving the dual-carbon objectives. Utilizing data from 279 prefecture-level cities during 2008 to 2021, this study employed a multi-phase differences-in-differences model to investigate the synergistic effects of the concurrent implementation of LCCP and CET (referred to as the “dual pilot” policy) on RPCE. The findings revealed that (1) the dual pilot policies reduced per capita CO₂ emissions by 0.644% and PM_2.5 concentration by 0.114%, with the dual effect being significantly superior to that of single pilot policies; (2) through mechanism analysis, it was found that technological innovation and clean energy transition served as the principal channels through which the “dual pilot” policy exerted its influence on RPCE; and (3) heterogeneity analysis demonstrated that the “dual pilot” policy was particularly effective in the RPCE in big cities, non-resource-based cities, and highly urbanized cities. This study provides novel empirical evidence supporting the integration of active government intervention with effective market mechanisms to maximize synergies in carbon emission reduction policies and achieve RPCE. Full article

The growth of human activity in cities is a key factor in the degradation of air quality. Numerous studies have demonstrated the link between air quality and the existence of dangerous and chronic diseases that are extremely costly for individuals and society. This study presents an analytical framework that compares fixed and mobile air-quality monitoring approaches in cities with limited resources, using Mohammedia city, Morocco, as an example. The framework centers on mobile monitoring units mounted on vehicles and equipped with affordable sensors, GPS technology, and wireless communication systems to track important pollutants, including fine particulate matter (PM_2.5 and PM₁₀) and harmful gaseous compounds (NO₂, SO₂, CO, O₃). The evaluation relies on scenario-based modeling, performance data from existing literature, and calculations of costs throughout the system’s lifetime. To enhance measurement reliability, the researchers developed a correction system that addresses measurement errors caused by temperature, humidity, vehicle speed, vibrations, traffic-related interference, operational interruptions, and communication limitations. The findings indicate that fixed monitoring stations deliver superior measurement precision, with estimated uncertainty ranging from ±1.2–2.5%, though their coverage area is restricted to 0.534 km² (representing 1.6% of Mohammedia). In comparison, the suggested mobile setup could potentially monitor 9.8 km², covering approximately 30% of the city, while decreasing infrastructure needs and setup time (2–4 h compared to 2–4 weeks). Over 10 years, the total cost is EUR 252,000 for mobile monitoring, compared with EUR 3.6 million for a network of 20 fixed stations. These results demonstrate that corrected mobile monitoring systems offer significant promise as an economical and sustainable approach for managing urban environmental conditions. Full article

Residential heating is a major contributor to atmospheric pollution, especially in populated areas. Traditional methods for measuring emissions, such as chimney probes, are limited due to the need for prior owner consent, which can compromise the reliability of results—particularly when detecting the illegal burning of materials like plastic or waste oil. This study introduces a mobile air pollution monitoring system using compact sensor modules installed on vehicles and drones. These autonomous modules are equipped with gas, particulate matter, and environmental sensors, along with Global Positioning System (GPS) tracking to record pollutant concentrations in real time and associate them with specific geographic locations. Field experiments conducted in Hungary and Uzbekistan demonstrated the system’s effectiveness in detecting elevated pollutant levels in rural areas with solid fuel heating and in urban zones affected by industrial activity and traffic. For instance, PM2.5 concentrations ranged from 15 μg/m³ in forested areas to as high as 160 μg/m³ in industrial zones, while CO₂ levels near chimneys exceeded background values by 15–25 ppm. Drone-based measurements enabled vertical profiling and direct analysis of emissions from individual chimneys, providing detailed spatial distribution data. The proposed mobile sensing approach allows for the accurate localization of pollution sources and the assessment of air quality variations within small-scale environments. This method overcomes limitations of stationary or pre-announced inspections and supports proactive environmental monitoring and enforcement. Full article

Background/Objectives: Although the adverse metabolic effects of PM2.5 and the health benefits of physical activity are well-established, evidence on whether physical activity modifies the association between PM2.5 exposure and metabolic syndrome or health-related quality of life (HRQoL) remains limited. Methods: This observational analytical cross-sectional study examined the modifying effect of physical activity on the associations between long-term PM2.5 exposure and metabolic syndrome and HRQoL in Chiang Mai, Thailand, and to explore these associations across physical activity levels using stratified analyses. A total of 347 participants (209 from higher PM2.5 areas and 138 from lower PM2.5 areas) were recruited in Chiang Mai between March and May 2024. Metabolic syndrome was assessed using blood tests and anthropometric measurement, while HRQoL was evaluated using the Thai version of the SF-36 questionnaire. Multivariable logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for metabolic syndrome. HRQoL differences were analyzed using generalized linear models with robust standard errors. Interaction between PM2.5 exposure and physical activity was assessed to examine potential effect modification. All models were adjusted for age, sex, BMI, smoking status, and educational level, with additional stratified analyses across physical activity levels. Results: Higher long-term PM2.5 exposure was associated with lower odds of metabolic syndrome (OR = 0.34, 95% CI: 0.14–0.83) but was not associated with HRQoL. Physical activity was not independently associated with either outcome, and no interaction between PM2.5 exposure and physical activity was observed. In stratified analyses, the inverse association between PM2.5 exposure and metabolic syndrome was observed only among individuals with high physical activity, while significantly lower HRQoL scores were observed among those with moderate and high physical activity levels. Conclusions: Higher long-term PM2.5 exposure was associated with lower odds of metabolic syndrome and lower HRQoL. Physical activity was not independently associated with these outcomes, and no interaction between PM2.5 exposure and physical activity was observed. Stratified analyses suggested variation in these associations across physical activity levels. Full article