Swapan K. Biswas

Urban air quality in the Asian region

Over the past decade, member states of the Regional Co-operation Agreement (RCA), an intergovernmental agreement for the East Asia and Pacific region under the auspices of the IAEA with the assistance of international organizations and financial institutions such as the World Bank and the Asian Development Bank, have started to set in place policies and legislation for air pollution abatement. To support planning and evaluate the effectiveness of control programs, data are needed that characterizes urban air quality. The focus of this measurement program describe in this report is on size segregated particulate air pollution. Such airborne particulate matter can have a significant impact on human health and urban visibility. These data provide the input to receptor models that may permit the mitigation of these impacts by identification and quantitative apportionment of the particle sources. The aim of this report is to provide an overview of the measurements of concentrations and composition of particulate air pollution in two size fractions across the participating countries. For many of the large cities in this region, the measured particulate matter concentrations are greater than air quality standards or guidelines that have been adopted in developed countries.

Impact of unleaded gasoline introduction on the concentration of lead in the air of Dhaka, Bangladesh

Abstract Airborne particulate matter (APM) samples collected at a semiresidential area in Dhaka, Bangladesh, during the periods of 1994 and 1997–2000 have been studied to assess the impact of the use of unleaded gasoline in Bangladesh. According to scanning electron microscopy/energy-dispersive X-ray microanalyzer studies, lead (Pb) was found as Pb sulfates and Pb halides in motor-vehicle exhaust particles, whose diameters were some hundreds of nanometers. No significant changes in the annual averages of APM mass and black carbon concentrations have been observed over the period. The yearly average Pb concentration reached a maximum value of 370 ng/m3 in the particulate matter with an aerodynamic diameter < 2.5 µm fraction in 1998. In 2000, the concentration decreased to approximately one-third (106 ng/m3) of the high earlier values after the introduction of unleaded gasoline in 1999. A significant lowering of the blood Pb level of the population over next few years is expected as a result of this great decrease in Pb concentration.

Investigation of Sources of Atmospheric Aerosol at a Hot Spot Area in Dhaka, Bangladesh

Abstract Samples of fine and coarse fractions of airborne particulate matter were collected at the Farm Gate area in Dhaka from July 2001 to March 2002. Dhaka is a hot spot area with very high pollutant concentrations because of the proximity of major roadways. The samples were collected using a “Gent” stacked filter unit in two fractions of 0- to 2.2-μm and 2.2- to 10-μm sizes. The samples were analyzed for elemental concentrations by particle-induced X-ray excitation (PIXE) and for black carbon by reflectivity methods, respectively. The data were analyzed by positive matrix factorization (PMF) to identify the possible sources of atmospheric aerosols in this area. Six sources were found for both the coarse and fine PM fractions. The data sets were also analyzed by an expanded model to explore additional sources. Seven and six factors were obtained for coarse and fine PM fractions, respectively, in these analyses. The identified sources are motor vehicle, soil dust, emissions from construction activities, sea salt, biomass burning/brick kiln, resuspended/fugitive Pb, and two-stroke engines. From the expanded modeling, ∼50% of the total PM2.2 mass can be attributed to motor vehicles, including two-stroke engine vehicle in this hot spot in Dhaka, whereas the PMF modeling indicates that 45% of the total PM2.2 mass is from motor vehicles. The PMF2 and expanded models could resolve ∼4% and 3% of the total PM2.2 mass as resuspended/fugitive Pb, respectively.Although, Pb has been eliminated from gasoline in Bangladesh since July 1999, there still may be substantial amounts of accumulated lead in the dust near roadways as well as fugitive Pb emissions from battery reclaimation and other industries. Soil dust is the largest component of the coarse particle fraction (PM2.2–10) accounting for ∼71% of the total PM2.2–10 mass in the expanded model, whereas from the PMF modeling, the dust (undifferentiated) contribution is ∼49%.

Long-range transport of soil dust and smoke pollution in the South Asian region

Transboundary transport of air pollution in the South Asian region has been an issue of increasing importance over the past several decades. Long–range transport of anthropogenic pollution is contrasted with that of pollution produced by natural processes such as dust storms or natural forest fires. Airborne particulate matter datasets covering the period from 2002 to 2007 from the neighboring countries like Bangladesh, India, Pakistan and Sri Lanka were used to find the source areas that are primarily responsible for long range transported pollutants. All four countries collected samples with the same type of sampler and follow the same technique for mass and BC measurements. It was found that high fine soil contributions were from dust storms. On the other hand, smoke in this region mainly comes from northern India where agricultural waste is often burned.

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 four-stroke engines, and they emit as much of an order of magnitude and more particulate matter (PM) than four-stroke 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 high-pollutant 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 μm and 2.2–10 μm 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.