Bilkis A. Begum

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.

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%.

Air pollution by fine particulate matter in Bangladesh

Abstract In Dhaka, Bangladesh, particular matter (PM) is the air pollutant that is most harmful to public health and the environment when compared to other measured criteria pollutants. During recent years, the Government of Bangladesh has tried to control PM emissions coming from anthropogenic sources. About 30–50% of the PM 10 mass in Dhaka (depending on location) is in fine particles with aerodynamic diameter less than 2.2 µm. These particles are mainly of anthropogenic origin and predominately from transport–related sources. However, the combination of meteorological conditions, long–range transport during the winter and local sources results in PM concentrations remaining much higher than the Bangladesh National Ambient Air Quality Standard (BNAAQS). It has been found that black carbon accounted for about 50% of the total fine PM mass before the adoption of control policies. As a result, the PM emission as well as BC has not increased in proportion to the increase in the number of combustion sources like motor vehicles, diesel power generator or brick kiln. Positive Matrix Factorization (PMF) was applied to fine particle composition data from January 2007 to February 2009. It was found that motor vehicles contribute less BC with respect to brick kiln industry. This result demonstrates the effectiveness of the government’s policy interventions since previously vehicles represented the major contributors of BC. BC is also transported over long distances, mixing with other particles along the way as demonstrated by a potential source contribution function analysis. Transboundary transport of air pollution in the South Asian region has become an issue of increasing importance over the past several decades. The relative amounts of local and long–range transported pollutants are currently unknown.

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.

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

Fine particulate matter (PM2.5) samples were simultaneously collected on Teflon and quartz filters between February 2010 and February 2011 at an urban monitoring site (CAMS2) in Dhaka, Bangladesh. The samples were collected using AirMetrics MiniVol samplers. The samples on Teflon filters were analyzed for their elemental composition by PIXE and PESA. Particulate carbon on quartz filters was analyzed using the IMPROVE thermal optical reflectance (TOR) method that divides carbon into four organic carbons (OC), pyrolized organic carbon (OP), and three elemental carbon (EC) fractions. The data were analyzed by positive matrix factorization using the PMF2 program. Initially, only total OC and total EC were included in the analysis and five sources, including road dust, sea salt and Zn, soil dust, motor vehicles, and brick kilns, were obtained. In the second analysis, the eight carbon fractions (OC1, OC2, OC3, OC4, OP, EC1, EC2, EC3) were included in order to ascertain whether additional source information could be extracted from the data. In this case, it is possible to identify more sources than with only total OC and EC. The motor vehicle source was separated into gasoline and diesel emissions and a fugitive Pb source was identified. Brick kilns contribute 7.9 μg/m3 and 6.0 μg/m3 of OC and EC, respectively, to the fine particulate matter based on the two results. From the estimated mass extinction coefficients and the apportioned source contributions, soil dust, brick kiln, diesel, gasoline, and the Pb sources were found to contribute most strongly to visibility degradation, particularly in the winter. Implications: Fine particle concentrations in Dhaka, Bangladesh, are very high and cause significant degradation of urban visibility. This work shows that using carbon fraction data from the IMPROVE OC/EC protocol provides improved source apportionment. Soil dust, brick kiln, diesel, gasoline, and the Pb sources contribute strongly to haze, particularly in the winter.

Effect of dust charge fluctuation on the Alfvén wave propagation in a magnetized dusty plasma

Growth rates of propagating waves in a magnetized dusty plasma are studied for various values of natural decay rate for the presence of dust charge fluctuation in the case of hot ions and electrons and for a weak magnetic field. The dispersion relation is obtained for the waves that propagate through low-frequency plasma with velocity, VA=B0/(μominio)1/2. Consistency of the results with previous work [Alam et al., Astrophys. Space Sci. 259, 15 (1998)] is discussed and the physical situation is also seen to be the situation considered in Varma et al. [Phys. Rev. E 47, 3612 (1993)] and Melandso et al. [Planet Space Sci. 41, 321 (1993)]. At last, numerical estimates of the growth rate as a function of the attachment frequency, the decay rate for its various range of values have been done and are displayed graphically.

Identification and apportionment of sources from air particulate matter at urban environments in Bangladesh

Particulate air pollution is the major concern in four major cities, Rajshahi, Dhaka, Khulna and Chittagong, in Bangladesh and thus it is necessary to understand the characteristics of the pollutant as well as sources for further improvement of the air quality. In this view particulate matter (PM) sampling was done between September 2010 to July 2012 from four Continuous Air Monitoring Stations (CAMS) located at Sapura in Rajshahi, Farm Gate in Dhaka, Baira in Khulna and a TV station, Khulshi, in Chittagong. PM sampling was performed using dichotomous samplers, which collect samples in two sizes: PM2.5 and PM2.5-10. All the samples were analyzed for mass, black carbon (BC), delta-C and elemental compositions. The data sets for each site were analyzed for sources with PMF2 modeling. The identified sources include brick kilns, soil dust, road dust, motor vehicle, metal smelter, fugitive Pb, Zn source and sea salt sources in case of coarse Original Research Article British Journal of Applied Science & Technology, 4(27): 3930-3955, 2014 3931 particles (PM2.5-10) depending on site. Among them, more than 62% of the PM2.5-10 was soil and road dust in Rajshahi, Chittagong and Khulna sites but in Dhaka, the dust contribution was about 38%. For fine particles (PM2.5), the identified sources are similar to those for the coarse particle samples, but their contributions are different. It was found that more than 63% of the fine particle mass comes from anthropogenic sources such as brick kilns, wood burning, biomass burning, and motor vehicles. The contribution of mass as well as black carbon and delta-C from the motor vehicles is much less than from brick kilns or biomass burning sources. The Government of Bangladesh is trying to reduce the emission from brick kilns by adopting green technologies for brick production. There is also long range transport of fine particles during winter time. The impacts of local sources also increase due to poorer dispersion conditions in the winter. Hence in order to reduce the local particulate pollution, it will be necessary to take policy actions regionally.

On the generation of magnetic fields due to ponderomotive forces in astrophysical plasmas

The generation of magnetic fields due to ponderomotive forces in astrophysical plasma consisting of electrons, ions and positrons is investigated theoretically. It is seen that collisional or non-collisional interactions (between electromagnetic waves and plasma particles) via ponderomotive forces in an inhomogeneous plasma can excite a magnetic field. The growth rate of the magnetic field is illustrated graphically for different values of the temperature and concentration of positrons in the plasma.