10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Trends in Particulate Matter Concentrations in Different Parts of Bangladesh
Munjurul Hannan Khan, MD. MASUD RANA, Clean Air and Sustainable Environment Project
Abstract Number: 1178 Working Group: Aerosol Exposure
Abstract Bangladesh suffers from severe air pollution, especially during dry season (November–April). Thick smog and dusts choke the country in this season every year. The country is densely populated, and a large number of rural and slum-dwelling people are exposed to such pollution. In this study, we investigated temporal and directional variations in PM concentrations in 8 district-cities located in different parts of the country. Hourly PM10 and PM2.5 concentrations in the middle (Dhaka, Gazipur, Narayanganj), south-east (Chittagong), north-east (Sylhet), south (Barisal, Khulna) and north-west (Rajshahi) of the country were captured using beta-attenuation method from 2013 to 2015. The data were quality controlled and analyzed with software “R” to understand seasonal, diurnal and directional characteristics of PM concentrations. Given importance to the capital city of Dhaka, long-range pollution to this city was also investigated - ninety-six-hour backward trajectories for the whole dry season were computed near the city using HYSPLIT model, associated with the corresponding PM concentrations and analyzed to trace long-range hotspots responsible for introducing pollutants into the atmosphere of Dhaka. The study found yearly PM10 concentrations in the stations about three times and yearly PM2.5 concentrations about six times greater than the national standards of Bangladesh. The country experienced several air pollution episodes in dry season when PM2.5 concentrations were 8–13 times greater than the World Health Organization (WHO) guideline value. Higher PM pollution and great contribution of fine particles most of the time were associated with the north-westerly wind. The city of Dhaka and its neighboring areas were found the most polluted among the cities. During winter (November to January) which was observed as the most polluted season, average PM10 concentrations in Dhaka, Gazipur, and Narayanganj were 257.1, 240.3, and 327.4 μg m−3, respectively. Contributions of fine particles to the PM were also high in the winter season (>75%) compared to that in the wet season (~50%). Pollution levels during wet season (May–October) were, although found legitimate as per the national standards of Bangladesh, exceeded WHO guideline value in 50 % of the days. Trans-boundary source identifications using concentration weighted trajectory method revealed that the sources in the eastern Indian region bordering Bangladesh, north-eastern Indian region bordering Nepal and Nepal and its neighboring areas had high probability of contributing to the PM pollutions near Dhaka city.