Monitoring and characterization of PM10 and PM 2.5 air-borne particulate matter in Dhaka city

Abstract

Samples of Air-borne Particulate Matter (APM) in the size range 0-2.5 J.llll (PM2s) and 0-10 J.lm(PM10) were collected simultaneously using two MiniVol portable air samplers at two major locations in Dhaka city: Mohakhali and Farmgate. At Mohakhali effective sampling duration was from May 16 to May 23,2004 and at Farmgate from June 6 to June 13, 2004. Continuous seven day monitoring at each site was can.ied out to find the effect of traffic load on ambient Particulate Matter (PM) pollution level. Weekday and weekend average traffic number was evaluated by field technicians at both locations. Both the locations are regarded heavily polluted because of the proximity of major roadways. Concentration levels ofPM10 and PM1.5 were found higher at Mohakhali than at Fanngate. Daily and weekly average concentrations of PM,o and PM2.5 at Mohakhali were found higher than USEPA 24-hrs average guideline values but at Farmgate concentrations were within the guideline. Average concentrations of Organic Matter (OM) and Inorganic Matter (1M) in PM]o, and OM, 1M and Black Carbon (BC) in PM25 at Mohakhali were also found higher than that at Fatmgate. Concentrations of most of the trace metals that are characteristic signatures for industrial emission and fugitive emission from soil were found higher at Mohakhali. Analysis results of PM show that maximum ambient concentration (24-h average) of Arsenic, Copper, Manganese and Zinc were above the guideline values of different developed nijtions. Increasing ambient concentrations of Na+ from the end of the pre monsoon (May) to beginning of the monsoon (June) confirms the contribution of sea spray as Na+ is regarded as reference element for maritime aerosols.