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.
