Twenty-Five Years of Air Quality in Bangladesh: Trends, Seasonality, and Spatial Pollution Regimes

Pattern of air pollutants and land surface temperature in Nigeria using space-time pattern mining techniques

Spatio-temporal Assessment of Air Quality Across Diverse Land-use Zones in Ranchi, Jharkhand, India

Air-quality research in India has predominantly focused on large metropolitan regions, leaving plateau-based Tier-II cities comparatively underexamined. This study assessed the spatio-temporal variability of air quality across five land-use zones in Ranchi, Jharkhand: industrial, traffic, residential, agricultural, and eco-sensitive. Monthly observations collected during 2022–2023 yielded 120 site-month records, and the National Air Quality Index framework was applied to PM₂.₅, PM₁₀, SO₂, and NO₂. Site-level differences were evaluated using one-way analysis of variance, while dominant-pollutant regimes and seasonal patterns were examined to identify spatial and temporal contrasts. Mean AQI differed significantly among sites (F(4, 115) = 11.04, p < 0.001). The traffic site recorded the highest mean AQI (267.7 ± 27.2), followed by the industrial site (243.2 ± 16.9), indicating sustained pollution pressure in high-emission zones. The eco-sensitive site recorded a higher mean AQI (175.1 ± 105.4) than the residential site (158.6 ± 58.0), suggesting that local vegetation did not consistently prevent episodic deterioration. PM₂.₅ was the most frequent AQI-determining pollutant, particularly at the traffic and industrial sites, whereas PM₁₀ governed several abrupt episodes at the agricultural and eco-sensitive locations. Winter generally showed the highest and most variable AQI, while the monsoon produced lower and less dispersed values, reflecting seasonal differences in pollutant accumulation and removal. Overall, the findings demonstrate marked land-use and seasonal heterogeneity in Ranchi. They further indicate that air-quality monitoring and management should address both persistent emissions at traffic and industrial locations and episodic pollution affecting peri-urban, agricultural, and eco-sensitive zones within the rapidly expanding plateau-based urban environment.

“Seasonal Air Quality Dynamics in Urban Slums of Dhaka Metropolitan Area”

Bangladesh being a developing country in South Asia, is facing the challenge of air pollution for a long time now. The capital city Dhaka stands out within top 3 polluted cities in the entire earth. Inside Dhaka metropolitan area, the slums are often regarded as the most polluted locations. Still these areas are not explored properly in terms of slum-specific air pollution state. Thus, this study measures air pollution at 5 major slum areas of the Dhaka metropolitan area i.e. Shagufta, Bauniabadh, Bhasantek, Korail and Ceramic Bazar through an air quality monitoring system (AQMS) installed in each site for 2025. The collected data include values of particulate matter ((PM1, PM2.5, PM4, PM10), gaseous substances (CO2, NO2, SO2) and atmospheric variables (temperature and relative humidity). The collected data was taken into Microsoft excel and cleaning process was performed. Then the data for these variables were grouped by four seasons i.e., summer, monsoon, post-monsoon and winter and after analysis using RStudio, these were compared among the slum locations. This revealed that Korail, Bhasantek and Ceramic bazar are comparatively more polluted in terms of particulate matter, whereas Shagufta is more polluted by other gaseous traces. The analysis indicates winter as the most polluted season and monsoon as the least. Pearson's correlation analysis revealed the interconnectedness among these variables, where particulate matter exhibited high positive correlation with one another. Principal component analysis revealed particulate matter as the dominant pollutant. Under these circumstances, the study provides slum-specific recommendations e.g., awareness campaign, waste management etc.

Changes of Urban and Suburban Air Quality Patterns during the Pandemic Year 2020: Longitudinal Evidence from Three Romanian Citie

Urban areas must develop and implement air pollution-reduction strategies in order to comply with progressively stricter air quality standards. Various measures imposed during the lockdowns associated to COVID-19 pandemic worldwide made the year 2020 an exceptional period for global air pollution: air pollutant emission patterns were significantly and differently altered. Atmospheric pollutant levels varied from the lowest to the highest values. Within this context, present study aim is to emphasize comparatively the changes in major air pollutants’ concentrations PM10, PM2.5, NO, NO2, NOx, CO, SO2, O3 in three important urban centers (Bucharest, Brașov, Iași) in Romania during 2020. The contrast in mass concentrations of major air pollutants in the urban and the suburban areas of above cities has been studied using longitudinal analysis, probability density functions and change point analysis. The study outcomes extend the knowledge about air pollution at local/regional scale and are of help in designing air pollution control strategies.

Spatio-Temporal Assessment of Air Quality and AQI in Former Khanh Hoa Province, Vietnam (2021-2024)

Air pollution has become an increasingly important environmental and public health concern, particularly in rapidly urbanizing coastal provinces. This study aimed to evaluate the spatio-temporal variation characteristics of key air quality parameters (TSP, SO₂, NO₂, and CO) and the Air Quality Index (AQI) in former Khanh Hoa Province during the period 2021-2024. Periodic monitoring data collected from 28 monitoring sites across four functional zones (North, South, West, and Central) were analyzed using descriptive statistics, seasonal comparison, Pearson correlation analysis, AQI calculation, and GIS-based spatial interpolation (IDW). The results showed that SO₂ and CO concentrations significantly decreased by 62% and 22%, respectively (p<0.05), while NO₂ remained relatively stable and TSP showed signs of increasing, particularly in 2024. TSP was identified as the dominant pollutant, accounting for more than 95% of AQI deterioration and frequently exceeding the annual average standard in the Central region. Overall air quality was generally classified as “Good” and “Moderate”; however, localized pollution hotspots and short-term unhealthy AQI events were observed, especially during the dry season in urbanized areas with high traffic density and intensive construction activities. Pearson correlation analysis revealed that humidity and wind speed played important roles in pollutant dispersion and washout effects, while noise levels showed significant positive correlations with TSP, NO₂, and CO, indicating the strong influence of transportation-related emissions. These findings suggest that air quality management should prioritize TSP source control, particularly in the Central region, and strengthen seasonal monitoring strategies to support sustainable environmental management in rapidly developing coastal provinces of Vietnam.

Long-Term Assessment of Ambient Air Quality, Meteorological Influence, and Transboundary Transport in a Tier-II Indian City