Spatial Distribution of Air Quality in Moulvibazar District Town, Bangladesh: A Wintertime Observation

Since air pollution in Bangladesh's urban areas is becoming more prevalent, most study has concentrated on major metropolitan cities, leaving smaller urban centers understudied. In order to address that gap, this study investigated the air quality in Moulvibazar, a district of Sylhet Division. This study aims to assess the concentrations of Particulate Matter (PM<sub>1</sub>, PM<sub>2.5</sub> and PM<sub>10</sub>) and Carbon Monoxide (CO) across different land-use types in district town of Moulvibazar. Air quality monitoring was conducted at 60 locations using a portable Air Quality Monitor, Indoor Outdoor Formaldehyde (HCHO) Detector (Model: DM106) and a portable CO Meter (Model: AS8700A) to determine the parameters. Descriptive statistics and whisker box plots were also employed to analyze and visualize the variations in pollutant concentrations across different locations. Additionally, ArcGIS software (10.4.1. version) was used for spatial analysis, and a dendrogram plot was created to classify and interpret data clusters, providing a deeper understanding of the spatial distribution of pollutants. The Department of Environment (DoE) established Bangladesh National Ambient Air Quality Standard (NAAQS) for PM<sub>2.5</sub>, PM<sub>10</sub>, and carbon monoxide (CO) at 65 µg/m<sup>3</sup>, 150 µg/m<sup>3</sup>, and 9 ppm, respectively. Results indicated that the average concentrations of PM<sub>1</sub>, PM<sub>2.5</sub> and PM<sub>10</sub> across these locations were 93.47 µg/m<sup>3</sup>, 154.82 µg/m<sup>3</sup>, and 198.95 µg/m<sup>3</sup>, respectively. The most polluted location was Modal Thana (a commercial area) where PM<sub>1</sub>, PM<sub>2.5</sub> and PM<sub>10</sub> concentration were 154, 241.5 and 319.25 µg/m<sup>3</sup>, respectively. CO concentrations in the most polluted area were found to be 2.27 times higher than the NAAQS standards. Despite these findings, the variations in pollutant concentrations across different land-use types were statistically insignificant. Road intersections recorded the highest average PM<sub>2.5</sub> concentration (168.30 µg/m<sup>3</sup>), whereas the lowest average data of PM<sub>2.5</sub> found in industrial areas (149.25 µg/m<sup>3</sup>). The study finds worthwhile air quality issues in Moulvibazar, with pollutant levels exceeding the NAAQS. Urgent actions, such as pollution control and sustainable urban development, are required to address these concerns.