Impact of Banning of Two-Stroke Engines on Airborne Particulate Matter Concentrations in Dhaka, Bangladesh

Abstract

Vehicular air pollution is common in growing metropolitan areas throughout the world. Vehicular emissions of fine particles are particularly harmful because they occur near ground level, close to where people live and work. Two-stroke engines represented an important contribution to the motor vehicle emissions where they constitute approximately half of the total vehicle fleet in Dhaka city. Two-stroke engines have lower fuel efficiency than fourstroke engines, and they emit as much of an order of magnitude and more particulate matter (PM) than fourstroke engines of similar size. To eliminate their impact on air quality, the government of Bangladesh promulgated an order banning all two-stroke engines from the roads in Dhaka starting on December 31, 2002. The effect of the banning of two-stroke engines on airborne PM was studied at the Farm Gate air quality-monitoring station in Dhaka (capital of Bangladesh), a hot spot with very highpollutant concentrations because of its proximity to major roadways. The samples were collected using a "Gent" stacked filter unit in two fractions of 0 -2.2 m and 2.2-10 m sizes. Samples of fine and coarse fractions of airborne PM collected from 2000 to 2004 were studied. It has been found that the fine PM and black carbon concentrations decreased from the previous years because of the banning of two-stroke engine baby taxies.

Trend of ambient air quality in Chittagong City

“…Similar scenario is also present for the second largest city of Bangladesh. Impact of banning of two-stroke engine of airborne particulate matter concentrations in Dhaka has been studied (Begum et al, 2006). Atmospheric pollution in urban areas is a major issue in many developing countries around the world.…”

Identification of haze-creating sources from fine particulate matter in Dhaka aerosol using carbon fractions

“…This factor would include both cars and motorbikes. The three-wheel taxis in Dhaka all are fueled by CNG (Begum et al, 2006b).…”

Sources of Carbonaceous Materials in the Airborne Particulate Matter of Dhaka

“…BC concentrations were observed to vary from month to month depending on the meteorological conditions. It has been found that the concentration has decreased relative to previous years as a result of policies adopted by the government (Begum, 2006a). PM and BC concentrations in the AirMetrics and MOUDI samples were compared.…”

“…The HS site is a heavily traffic-impacted site while the SR site is in a residential area. The sources of the observed PM for these sites have been extensively discussed in prior source apportionment studies (Begum et al, 2010(Begum et al, , 2008(Begum et al, , 2006a(Begum et al, , b, 2004.…”

“…In a previous study, Biswas et al (2001) found that approximately 40% of fine PM (⁄2.5 μm) is BC. The important sources of PM in Dhaka were identified as diesel-powered vehicles, two-stroke engine gasoline vehicles, and brick kilns (Begum et al, 2006a(Begum et al, , 2005a(Begum et al, , 2004Salam et al, 2003). These studies have suggested that motorized transport vehicles were the single largest contributor to particulate air pollution especially to fine particulate matter concentrations in Dhaka.…”