Investigating Incursion of Transboundary Pollution into the Atmosphere of Dhaka, Bangladesh

Md Masud Rana,Munjurul Hannan Khan,Norela Sulaiman,Bjarne Sivertsen,Mastura Mahmud

doi:10.1155/2016/8318453

Abstract

Concentrations of particulate matter (PM) in Dhaka, Bangladesh, during November 2013 to April 2014 were found 7-8 times higher than the World Health Organization (WHO) guideline value. Probability of contribution of transboundary sources to this PM pollution was investigated through different approaches. Ninety-six-hour backward trajectories with every 3-hour interval were computed and clustered into 06 groups based on angle distance matrix. Probabilities of individual cluster to be associated with different ranges of coarse and fine particles were studied. Gazipur station near Dhaka city was found to have 68% probability of receiving PM10concentration higher than 150 μg/m3when air masses followed the route of Middle East through the Himalayan valley to the station. This channel was identified as the main route of PM transport to Bangladesh during dry season. Transboundary source-regions were spotted by concentration weighted trajectory (CWT) method and also by the monthly average aerosol optical depths (AOD) over South Asia. North-western Indian regions, Nepal and its neighboring areas, and Indian state of West Bengal were identified as the most probable zones that might have contributed to PM pollution in Gazipur, Dhaka. November to January was the high time the station had experienced fine particles from those transboundary regions.

Highlights

The city of Dhaka, Bangladesh, and its vicinity severely suffer from high level of particulate matter (PM) concentrations in the atmosphere, especially during dry season (November– April) [1,2,3]
We investigated through different approaches the contributions of transboundary sources to this pollution in Dhaka
High contribution of PM2.5 to PM10 concentration was found during November to February

Summary

Introduction

The city of Dhaka, Bangladesh, and its vicinity severely suffer from high level of particulate matter (PM) concentrations in the atmosphere, especially during dry season (November– April) [1,2,3]. This study identified hotspots of PM pollution in South Asia throughout the dry season and investigated probabilities of transboundary PM transport towards Dhaka city through different routes For this purpose, 96-hour backward trajectories equated on Gazipur, Dhaka, throughout the dry season (November 2013 to April 2014) and their associations with respective hourly PM10 concentrations and PM2.5 to PM10 ratio were exhaustively examined. 96-hour backward trajectories equated on Gazipur, Dhaka, throughout the dry season (November 2013 to April 2014) and their associations with respective hourly PM10 concentrations and PM2.5 to PM10 ratio were exhaustively examined Such long term associations and their analyses against local source profiles are important to understand the features of transboundary pollution into a region.

Materials and Methods

Results and Discussions

18 Longitude

Conclusion