Air pollution is a growing environmental issue in rapidly urbanizing Asian cities, where meteorological conditions and seasonal variability strongly influence pollutant concentrations. This review synthesizes published evidence on the interactions between meteorology, seasonality, and urban air pollution across selected cities in East Asia, South Asia, and Southeast Asia. The literature was collected from major scientific databases and organized according to meteorological drivers, seasonal characteristics, and dominant emission sources. Particular emphasis was placed on particulate matter (PM2.5 and PM10), SO2, NO2, NOx, CO, and O3. The reviewed studies indicate that wind speed and direction, precipitation, temperature, atmospheric stability, and monsoon circulation strongly influence pollutant transport, dispersion, and removal. Pollutant concentrations generally reach their highest in winter due to stagnant conditions and higher human emissions. In contrast, the summer and monsoon seasons tend to have lower PM levels due to better atmospheric mixing and wet deposition. Regional differences in dominant sources were also observed, including coal combustion and heating in East Asia, traffic and biomass burning in South Asia, and biomass burning and transboundary transport in Southeast Asia. These findings highlight the importance of seasonally adaptive and region-specific air quality management strategies in Asian cities.
India suffers from severe fine particulate matter (PM2.5) air pollution in winter that harms public health and disrupts economic activities. Seasonal prediction of pollution severity could facilitate proactive mitigation planning but is hindered by incomplete understanding of the drivers of pollution variations. Here, using over a decade of quality-controlled Indian government PM2.5 monitoring data, we find that ∼70% of the interannual variations in winter PM2.5 pollution across northern India are explained by western disturbances (WDs)—prevailing extratropical storms originating from the Mediterranean region—through PM2.5 removal via enhanced ventilation and precipitation. These WDs are regulated by the location and strength of the subtropical jet traceable to sea surface temperature (SST) anomalies across the North Atlantic and tropical Indian Ocean during the preceding autumn. Using these preseason SST anomalies, we demonstrate the potential to predict winter WD precipitation and PM2.5 pollution severity one season ahead, with good agreement with observations (r2 = 0.52 to 0.69), which could facilitate proactive public policies and stakeholder mitigation actions.
Yuan-Yu Xie, Kieran M. R. Hunt, Rohit Gupta et al.· Science Advances· 0 citations
Surface ozone (O3) pollution has become an increasingly important constraint on further improvements in urban air quality, particularly in industrial cities where complex terrain, local emissions, and meteorological conditions interact. In this study, hourly air pollutants, meteorological parameters, and high-time-resolution volatile organic compound (VOC) observations collected at a single urban-core site during September from 2021 to 2024 were used to investigate O3 pollution characteristics, VOC reactivity, source contributions, and driving mechanisms in a resource-based heavy-industrial city in northwestern Henan Province, China. Ozone formation potential (OFP), diagnostic ratios, positive matrix factorization (PMF), meteorological normalization, and extreme gradient boosting combined with Shapley additive explanations (XGBoost-SHAP) were integrated to identify key reactive species, major sources, and meteorological–precursor interactions. The mean maximum daily 8 h average O3 concentrations were 113.44, 150.32, 123.59, and 154.18 μg·m−3 from 2021 to 2024, respectively, with the highest level observed in 2024 despite the lowest nitrogen dioxide (NO2) and carbon monoxide (CO) concentrations. O3 was positively correlated with temperature and negatively correlated with relative humidity, indicating the importance of hot and relatively dry conditions. Total VOC OFP first increased and then declined, with alkenes dominating in 2021 and aromatics exceeding alkenes after 2022. Ethene, m/p-xylene, toluene, and vinyl chloride were identified as priority reactive species. PMF results showed that mixed industrial processes and vehicle exhaust were the dominant VOC sources, contributing 32.3% and 23.8%, respectively. Under the original meteorological-normalization specification, represented meteorological features accounted for 64.7% of the modeled O3 increase during the study period. Sensitivity specifications retained meteorological dominance but showed that the exact share was model dependent. SHAP analysis further identified temperature, short-term temperature variation, relative humidity, alkenes, and NO2 as key drivers. These results suggest that O3 pollution in this heavy-industrial city is jointly shaped by favorable meteorological conditions, reactive VOCs, nitrogen oxides (NOx) chemistry, and combined industrial and traffic emissions. Accordingly, industrial processes, vehicle exhaust, and highly reactive VOC species are likely priority targets for mitigation, while the effectiveness of coordinated VOC–NOx control still warrants further regime-specific evaluation.
Hongyu Liu, Hui Wang, Bei-Bei Wang et al.· Atmosphere· 0 citations
The Indo-Gangetic Plain in South Asia frequently experiences severe haze during the post-monsoon season. The November 2024 haze event recorded the highest daily PM
2.5
concentrations in Delhi (696 µg/m³) and Lahore (621 µg/m³) over the past 5 years. These elevated PM
2.5
concentrations coincided with a prolonged period of regional-scale atmospheric stagnation and a shift in peak fire activity from the afternoon to the evening. Here, we show that both cities had elevated pollutant concentrations with correlations between PM
2.5
and planetary boundary layer height, lower-tropospheric stability, atmospheric heat deficit, relative humidity, and fire radiative power, consistent with accumulation of emissions from multiple sources, including regional biomass-burning emissions, under stagnant atmospheric conditions. We also highlight that positive geopotential height anomalies and the mechanism of anticyclonic stagnation and weak winds favored a high-pressure system, suppressing turbulent ventilation and accumulating pollution in the lower troposphere. Furthermore, air mass back trajectories overlapped the stubble-burning region ,and higher evening fire counts observed by a geostationary satellite emphasize the likely role of increased evening fire activity alongside other local and regional emissions in elevated air pollution concentrations. These results demonstrate that local and synoptic meteorology strongly aggravates haze events, suggesting emission control strategies should be guided by meteorological forecasts across regional airsheds.
Industrial expansion in southern Vietnam has intensified concerns regarding seasonal air pollution dynamics and associated health risks under tropical monsoon conditions. However, assessments linking interannual variability, source structure, and population-specific health risks in tropical industrial zones remain limited. This study monitored ambient air quality at 37 sites across nine industrial zone clusters in southern Vietnam over five consecutive years (2021–2025), with biannual campaigns during the dry season (March) and rainy season (October). Two-way ANOVA identified significant effects of both year and season on concentrations of PM10, SO2, NO2, CO, NH3, and H2S (all p < 0.05), with consistently higher dry-season levels, while noise remained invariant. Principal component analysis revealed clear seasonal separation along the primary axis (39.5% variance explained), and hierarchical cluster analysis confirmed season-dominated multivariate structure. Non-negative matrix factorization resolved four stable PM10-related source factors, with Factors 3 and 4 showing pollutant signatures consistent with combustion- and sulfur-associated emissions and contributing most strongly during the dry season. The observed seasonal patterns are associated with differences in meteorological conditions and emission activities between the dry and rainy seasons. Probabilistic assessment identified H2S, PM10, and NO2 as dominant risk drivers, among which H2S posed the greatest exposure concern across population groups, with a mean hazard quotient (HQ) reaching 10.26 in the dry season for the high-exposure group and P(HQ ⩾ 1) ≈ 1.000. GIS-based composite pollution mapping further revealed persistent high-risk hotspots in the East–Southeast industrial corridor, where high-risk area coverage increased from 27% in 2021 to approximately 36% during 2022–2025, a pattern spatially associated with industrial clustering, transport connectivity, and seasonal meteorological conditions. Overall, the findings suggest that the observed seasonal differences in source-related pollutant patterns, pollutant accumulation, and population health risk are consistent with the combined influence of meteorological conditions and seasonal emission activities in tropical industrial environments, providing evidence to support season-specific emission control and targeted public health protection strategies.
Le Viet Thang, K. Lưu, Hoa Kim Nguyen et al.· Environmental Research Commu...· 0 citations
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