Recent spatial gradients and time trends in Dhaka, Bangladesh, air pollution and their human health implications
Creators: name: Md Mostafijur Rahman
name: Mahamud, Shakil
name: Thurston, George D.
Publisher: name: Taylor & Francis
Year: 2019
Subjects: subject: Space Science
subject: Microbiology
subject: FOS: Biological sciences
subject: FOS: Biological sciences
subject: Biotechnology
subject: 59999 Environmental Sciences not elsewhere classified
subject: FOS: Earth and related environmental sciences
subject: FOS: Earth and related environmental sciences
subject: 39999 Chemical Sciences not elsewhere classified
subject: FOS: Chemical sciences
subject: FOS: Chemical sciences
subject: Science Policy

description: Dhaka, the capital of Bangladesh, is among the most polluted cities in the world. This research evaluates seasonal patterns, day-of-week patterns, spatial gradients, and trends in PM<sub>2.5</sub> (&lt;2.5 µm in aerodynamic diameter), PM<sub>10</sub> (&lt;10 µm in aerodynamic diameter), and gaseous pollutants concentrations (SO<sub>2</sub>, NO<sub>2</sub>, CO, and O<sub>3</sub>) monitored in Dhaka from 2013 to 2017. It expands on past work by considering multiple monitoring sites and air pollutants. Except for ozone, the average concentrations of these pollutants showed strong seasonal variation, with maximum during winter and minimum during monsoon, with the pollution concentration of PM<sub>2.5</sub> and PM<sub>10</sub> being roughly five- to sixfold higher during winter versus monsoon. Our comparisons of the pollutant concentrations with Bangladesh NAAQS and U.S. NAAQS limits analysis indicate particulate matter (PM<sub>2.5</sub> and PM<sub>10</sub>) as the air pollutants of greatest concern, as they frequently exceeded the Bangladesh NAAQS and U.S. NAAQS, especially during nonmonsoon time. In contrast, gaseous pollutants reported far fewer exceedances throughout the study period. During the study period, the highest number of exceedances of NAAQS limits in Dhaka City (Darus-Salam site) were found for PM<sub>2.5</sub> (72% of total study days), followed by PM<sub>10</sub> (40% of total study days), O<sub>3</sub> (1.7% of total study days), SO<sub>2</sub> (0.38% of total study days), and CO (0.25% of total study days). The trend analyses results showed statistically significant positive slopes over time for SO<sub>2</sub> (5.6 ppb yr<sup>−1</sup>, 95% confidence interval [CI]: 0.7, 10.5) and CO (0.32 ppm yr<sup>−1</sup>, 95% CI: 0.01, 0.56), which suggest increase in brick kilns operation and high-sulfur diesel use. Though statistically nonsignificant annual decreasing slopes for PM<sub>2.5</sub> (−4.6 µg/m<sup>3</sup> yr<sup>−1</sup>, 95% CI: −12.7, 3.6) and PM<sub>10</sub> (−2.7 µg/m<sup>3</sup> yr<sup>−1</sup>, 95% CI: −7.9, 2.5) were observed during this study period, the PM<sub>2.5</sub> concentration is still too high (~ 82.0 µg/m<sup>3</sup>) and can cause severe impact on human health. <i>Implications</i>: This study revealed key insights into air quality challenges across Dhaka, Bangladesh, indicating particulate matter (PM) as Dhaka’s most serious air pollutant threat to human health. The results of these analyses indicate that there is a need for immediate further investigations, and action based on those investigations, including the conduct local epidemiological PM exposure-human health effects studies for this city, in order to determine the most public health effective interventions.