particulate matter concentrations in the air of … 93.pdfparticulate matter concentrations in the...

Particulate Matter Concentrations in the Air of Dhaka and Gazipur City

During Winter: A comparative study

M. M. Hoque1*, B. A. Begum

2, A. M. Shawan

3 and S. J. Ahmed

1

1Department of Physics, Dhaka University of Engineering and Technology,Gazipur-1707, Bangladesh.

2Chemistry Division, Atomic Energy Center. P.O. Box No. 164, Dhaka-1000, Bangladesh.

3Department of Chemistry, Jagannath University, Dhaka-1100,Bangladesh.

*Corresponding author: [email protected]

Abstract:

The particulate matter (PM2.5 and PM10) concentrations in the air of Dhaka and Gazipur cities during

December, 2013 to February, 2014 have been studied. The PM status and the sources of air pollution

in these cities have been investigated. Sampling was done by Air Matrices Mini Vol. Sampler and the

quantity of PM2.5 and PM10 was detected by weighing the filters before and after exposure. The

sampling sites are Farmgate of Dhaka (CAMS-2 site), a very busy traffic point and Joydeppur of

Gazipur (CAMS-4 site), a semi-residential area. The concentrations of particulate matter samples were

determined by reflectance measurement. Basic statistic ratios of PM2.5 and PM10 have been analyzed.

The concentrations of PM2.5 and PM10 were not significantly changed with respect to that of previous

years. Though Farmgate of Dhaka is a very busy traffic point and Joydeppur of Gazipur is a semi-

residential area, the concentrations of PM2.5 and PM10 in the air of Joydebpur (Gazipur) has been found

higher than that of Farmgate (Dhaka) during the sampling period and the daily average of PM2.5 for

both the cities always exceeded the Bangladesh National Ambient Air Quality Standard (BNAAQS,

65 µg/ m3

for PM2.5). Brick kiln emission and long range transports may increase the concentrations

particulate matter in the air of Gazipur compared to that of Dhaka. Moreover, there may be an impact

of indoor air pollution on the air quality of Gazipur city.

Keywords: PM10, PM2.5, BNAAQS, CAMS-2, CAMS-4

40

P-ID 93 International Conference on Physics Sustainable Development & Technology (ICPSDT-2015)(August 19-20, 2015)

Department of Physics, CUET.

1. INTRODUCTION

Particulate matter pollution is a major concern in the large cities of Bangladesh. The main contributors of air

pollution are motor vehicles, brick kilns, diesel generators and industries. In recent years much research interest

has been shown on atmospheric particles as they influence on climate change and cause adverse health effects

[1-6]. Although significance of particulate matter in atmospheric and environmental process is pronounced, our

knowledge, especially in Bangladesh, on their concentration and sources are inadequate. Rapid industrialization

and economic development occurred in Dhaka and Gazipur cities during the recent years which may increase the

emission of various pollutants. Bilkis et al. have studied the source identification of particulate matter during

winter months in Dhaka city [4] and at urban and semi-urban areas [5] in Bangladesh by positive matrix

factorization. They found the contribution from elemental carbon fraction at Farmgate which in comparison to

Aminbazar is less. Because, at Farmgate, only the city vehicles ply on road and during the day time mostly 80%

of the vehicles are of duel-fueled engine. Particle sources (from coal and biomass burning in brick field) impacts

may be contributing haze at urban and semi-urban areas of Bangladesh.

Fine particulate matter with aerodynamic diameter less than 2.5 µm is a widespread air pollution object. Dhaka,

the eighth largest city in the world, has witnessed a rapid growth of urban population in recent times. As a result,

the number of motor vehicles increased significantly in Dhaka, there has been a steep rise in a heterogeneous

mixture of old technology vehicles despite that the road space is narrowing and the traffic congestion is reaching

in unmanageable proportions. As a result major traffic intersections in the city have turned to hot spots for air

pollution from vehicular emissions. Gazipur, a new city corporation is considered as one of the industrially

developed city in Bangladesh. High particulate matter (PM) levels and poor visibility in winter time have

become a serious problem there. Coal and biomass burning in brick field, vehicle exhaust, industrial and

residential emissions contribute to the ambient PM in this city.

During winter season brick kilns goes in operation. The pollution due to vehicles and brick kilns is then expected

to be high during winter. To our knowledge, the measurement on the pollution sources and concentration of

particulate matter in the air of Gazipur city are not yet reported. In this work, sampling was performed by

gravimetric method and the concentration and sources of particulate matter (PM2.5 and PM10) in two locations,

Farmgate and Joydebpur of Dhaka and Gazipur cities respectively, will be addressed and compared.

Page 141



2. MATERIALS AND METHOD

2.1 Sampling Sites and Sampling of PM2.5 and PM10

Sampling was done in two locations, Farmgate of Dhaka city and Joydebpur of Gazipur city. Farmgate is a hot

spot site due to the proximity of several major roadways intersection and large numbers of vehicles plying

through this area [7]. The site is commercial as well as semi industrial area. The Tejgaon industrial area is very

near to this site. At Farmgate, the samplers were placed on the flat roof of the guardhouse of Bangladesh

Agricultural Research Council (BARC). This location houses the second continuous air monitoring station

(CAMS-2) at Dhaka. Gazipur is a residential area of moderate population density. The sampling location is

within 20 m from a local road and about 200m from a secondary road with moderate traffic density. At Gazipur,

the samplers were placed on the flat roof of the continuous air monitoring station (CAMS-4) site of Clean Air

and Sustainable Environment (CASE) project, situated at Gazipur city corporation central symmetry, East

Chandana, Joydebpur. The Joydebpur Chourasta, which is a very busy traffic point, is about 5 km west to this

site. Joydebpur rail station, through which daily 60 trains pass away, is about 100m away from the sampling

location. At “Konabari” and “Kodda” which are about 5 to 7 km to the north-west of the sampling site, more

than 100 brick kilns are in production using kindle wood. There are many garments and other industries at 4 to 7

km distance from this site.

Particulate matter sampling was performed by using Air Metrics Mini Vol. sampler [8] for collecting both PM10

and PM2.5 samples from the Farm Gate site in Dhaka city and Joydebpur in Gazipur City. The Mini Vol. were

programmed to sample at 5 liter per minute through PM10 and PM2.5 particle size separators (impactors) and then

through 2m pore teflon filters. The actual flow rate should be 5 liter per minute at ambient conditions for proper

size fractionation. To ensure a constant flow of 5 liter per minute through the size separator at different air

temperatures and ambient pressures, the sampler flow rates were adjusted for the ambient conditions at the

sampling site. The Mini Vol. sampler was positioned with the intake upward and located in an unobstructed area

at least 30 cm from any obstacle to air flow and the sampler inlet was placed at a height of 10 m above ground

level. The intake nozzle of the samplers at the Farmgate location was about 5 m away from the main road. PM10

and PM2.5 were collected simultaneously for 24 hours average with two Mini Vol. samplers. The inlets of the

samplers were kept 45 cm apart from each other. The sampling was continued for three months, December 02,

2013 to February 28, 2014 (during winter time) at two locations, Farmgate and Joydebpur. Conditioned clean

filters were loaded to respective filter holder assembly at the CAMS conditioning room and were brought to

sampling site in separate clean polyethylene bags at each effective sampling day. After sampling, the filter

holder assemblies (keeping the exposed filters inside) were brought to the conditioning room of AECD directly

from the sampling site for conditioning and PM retrieval. Care was taken in transporting the exposed filter

holder assemblies, so that there should be no PM loss.

2.2 Traffic Volume at the Sampling Site:

A traffic survey was conducted by manual counting of vehicles in the Farm Gate corridor in front of the

sampling site and Gazipur Crossing on selected days during the study period to understand correlation between

PM concentrations and traffic volume. It was observed that the private cars were the main motorized vehicles

(80% of the total vehicles) plying along Farmgate corridor and most of them are of CNG driven. Besides this

many old minibus, bus, motor cycle, truck and covered vans were also run through the roadways. It was found

that heavy-duty diesel trucks and covered vans operated 17 times more frequently at night than during the day.

At Gazipur, the local roads which are very close to the sampling site, most of the vehicles are of 2-stroke petrol,

diesel or shallow engine (Nasimon). It is seen that at day time approximately 2500 numbers of different types of

vehicles (mostly diesel driven truck, van, pickup etc) ply per hour through Dhaka-Mymemsing road and 1750

numbers of vehicles (mostly 2-stroke baby taxi, motor cycle, mini-bus and human haler using shallow engine)

ply per hour through the station road, which is about 200 m north to the sampling site.

Page 142



2.3. Measurement of PM Mass:

PM mass was measured in the Chemistry Lab of the Atomic Energy Centre, Dhaka (AECD). The PM10 and PM2.5

samples were determined by weighing the filters before and after exposure using a microbalance [9]. The filters

were equilibrated for 24h at constant humidity of 50% and temperature (22C) in the balance room before each

weighing. A Po-210 (alpha emitter) electrostatic charge eliminator was used to eliminate the static charge

accumulated on the filters before each weighing. The difference in weights for each filter was calculated and the

mass concentrations for each PM10 or PM2.5 samples were determined. The concentrations of PM2.5 and PM10

were determined by reflectance measurement in AECD laboratory using an Evans Electro selenium Limited

(EEL) type Smoke Stain Reflectometer [10].

Fig. 1: Teflon Filters, before and after exposure.

2.4. Measurement of SOx and NOx:

This study mainly focused on the concentration of particulate matter, as they influence on climate change and

cause adverse health effects. However, SOx and NOx data were collected from CAMS-2 (Farmgate, Dhaka) as

well as CAMS-4(Gazipur). Since NOx have only annual standard (BNAAQS) [11], so for this pollutant daily 24-

hours average concentration levels were compared with the annual average. During data quality control some

data were flagged as invalid and those were not included in the analysis.

Page 143



3. RESULTS AND DISCUSSION

PM samplings were performed by using Air Metrics Mini Vol. sampler for collecting both PM2.5 and PM10 samples

for three months, December 2013 to February 2014 (i.e. during winter time) at two locations, Farmgate (Dhaka

city) and Joydebpur (Gazipur city). PM data was also collected from continuous air monitoring station (CAMS)

under Clean Air and Sustainable Environment (CASE) Project of the Department of Environment under Ministry

of environment and Forest, Bangladesh.

Concentration of PM2.5 in Dhaka and Gazipur during December 02, 2013 to February16, 2014 are presented in

Fig. 2. The highest concentration of PM 2.5 at Dhaka is found 246.5 µg/m3 on January 03, 2014 and at Gazipur, it

is 231.5 µg/m3

on December 12, 2013. The lowest concentration of PM 2.5 at Dhaka is found 40.2µg/m3 on

February16, 2014 and at Gazipur, it is 80.9µg/m3

on January 10, 2014. In Dhaka, PM2.5 concentration of January,

2014 is higher than that of February, 2014. Similarly in Gazipur, PM2.5 concentration of December, 2013 is

higher than that concentration of January, 2014. It is concluded that in the sampling period, the concentration of

PM 2.5 at Gazipur is higher than that of Dhaka and the daily average of PM 2.5 for both the cities always exceeds

the Bangladesh National Ambient Air Quality Standard (BNAAQS, 65 µg/ m3

for PM2.5)[11].

Concentration of PM10 in Dhaka and Gazipur during December 02, 2013 to February 25, 2014 are presented in

Fig. 3. The highest concentration of PM 10 at Dhaka is found 428.49 µg/m3 on February 6, 2014 and at Gazipur,

it is 358µg/m3

on January 8, 2014. The lowest concentration of PM 10 at Dhaka is found 87.2µg/m3

on January

18, 2014 and at Gazipur, it is 82µg/m3 on February 16, 2014. In Dhaka, PM10 concentration of December, 2013 is

higher than that of January, 2014. It is observed that in the month of December, 2013 the concentration of PM10

in Dhaka is more than that of Gazipur while in the months of January, 2014 and February, 2014 the

concentration of PM 10 in Dhaka is less than that of Gazipur. It may happen because there are a large number of

brick kilns at a distance of 5-7 km from the Gazipur sampling site. In winter brick kilns goes in operation. It is

also seen that almost in the sampling period (December 2013 to February 2014) the concentration of the daily

average of PM10 for both the cities do not comply with the required Bangladesh National Ambient Air Quality

Standard (BNAAQS,150 µg/m3for PM10)[11]

The ratio of PM2.5 and PM10 concentrations gives an idea of on the origin of the particulate pollution in

atmospheric air. Fig. 4. shows the ratio of the daily average concentration of PM2.5 and PM10 for Dhaka. The

ratio is 0.5. Fig. 5 shows the ratio of the daily average concentration of PM2.5 and PM10 for Gazipur. The ratio is

0.6. Therefore it is concluded that concentration PM10 in the air of Gazipur city is higher than that of Dhaka in

winter.

The last 10 years data (CASE, DoE) for concentration of PM 2.5 and PM 10 in the air of Dhaka were compared

with our investigations. We have found that our findings are in agreement with CASE data. Therefore, our study

reveals that, though the government has taken several steps to minimize air pollution but the concentration of

PM 2.5 and PM 10 remains almost same in Dhaka and can never comply the Bangladesh National Ambient Air

Quality Standard (BNAAQS).

Fig. 6 and Fig. 7. show the concentration of monthly average of PM2.5 and PM10, respectively, in the air of

Dhaka and Gazipur city. The concentration of PM2.5 in the air of Dhaka was found nearly the same in December,

2013 (123.2 µg/m3) and January, 2014 (126.4 µg/m

3) and decreases in February, 2014 (83.4 µg/m

3). In the air of

Gazipur city the concentration of PM2.5 was found maximum in December, 2013 (163.38 µg/m3) and then it

decreases in January, 2014 (136.02 µg/m3) and February, 2014 (138.3 µg/m

3). In the air of Dhaka city the

concentration of PM10 was found maximum in December, 2013 (291.5µg/m3) and then it decreases in January,

2014 (208.72µg/m3) and February, 2014 (178.34µg/m

3). Hence we can conclude that, in the eve of the winter

(December, 2013) the concentration of PM10 in the air of Gazipur was less than that of Dhaka. But when the

brick kilns were operated in full swing (January and February, 2014) the concentration of PM10 was less in the

Page 144



air of Gazipur than that of Dhaka. Moreover the variation in vehicle types ply in Dhaka and Gazipur city also

contributes in the PM level of these cities. It was observed that the private cars were the main motorized vehicles

(80% of the total vehicles) plying along Farmgate corridor and most of them are of CNG driven. But through

Joydebpur crossing of Gazipur, approximately 2500 numbers of different types of vehicles ply per hour at day

time and most of them are diesel driven truck, van and pickup.

Fig. 8 and Fig. 9. show the monthly average concentration of SOx and NOx in the air of Dhaka and Gazipur. It

was found that during the sampling period the average value of SO2 in the air of both Dhaka and Gazipur did not

exceed the limit value of Bangladesh National Ambient Air Quality Standard (BNAAQS, 140 ppb for SO2). The

highest value of SO2 was found 21.8 ppb for Dhaka in the month of February, 2014 and for Gazipur it was 15.4

ppb at the same time. The monthly average value of NOx for the air of Gazipur complied with the Bangladesh

National Ambient Air Quality Standard (BNAAQS, 53 ppb for NOx) during the sampling period while NOx

concentration at Farmgate, Dhaka found higher than annual average BNAAQS limit values (53 ppb). Here

observed 24-hours average was 167ppb and the maximum value was 238 ppb. CAMS-2(Farmgate, Dhaka) is a

road side monitoring station and higher traffic congestion may be cause for high NOx concentration.

From this study, it is seen that, the quality of the ambient air of both the Dhaka and Gazipur cities cannot meet

the Bangladesh National Ambient Air Quality Standard (BNAAQS) though sampling is performed in a very

busy traffic locations at Dhaka (Farmgate) and a residential area of Gazipur (Joydebpur).

Page 145



Figures and Tables

Fig. 2: Concentration of PM 2.5 in Dhaka and Gazipur (During Dec. 2013-Feb. 2014)

Fig. 3: Concentration of PM10 in Dhaka and Gazipur (During Dec. 2013- Feb. 2014)

Fig. 4: Concentration of PM2.5 /PM10 in Dhaka (During Dec. 2013-Feb. 2014)

Page 146



Fig. 5: Concentration of PM2.5 /PM10 in Gazipur (During Dec. 2013-Feb. 2014)

Fig. 6: Concentration of Monthly average of PM2.5 in Dhaka and Gazipur

(* Data was collected from CAMS-4,Gazipur)

Fig. 7: Concentration of Monthly average of PM10 in Dhaka and Gazipur

Page 147



Fig. 8: Monthly average concentrations (ppb) of NOx in the air of Dhaka and Gazipur

Fig. 9: Monthly average concentrations (ppb) of NOx in the air of Dhaka and Gazipur

Table-1. Concentrations of SOx and NOx in the air of Dhaka and Gazipur.

SO2(ppb) NOx(ppb)

Dhaka Gazipur Dhaka Gazipur

December,2013

Average 7.76 2.4 191 45.9

Maximum 13.3 3.63 273 98.6

Minimum 3.82 1.57 87.5 18

January,2014

Average 9.72 4.26 150 33.6

Maximum 20.3 7.13 224 77

Minimum 4.56 2.83 81.5 7.35

February,2014

Average 12.1 7.82 166.65 50.5

Maximum 21.8 15.4 238.15 139.46

Minimum 6.75 3.11 98.6 14.5

* Source: CAMS-2, Farmgate,Dhaka and CAMS-4, Gazipur.

Page 148



4. CONCLUSION

The Particulate matter concentration of PM2.5 and PM10 in the air of Dhaka and Gazipur city during winter period

has been compared. It was found that the concentration of PM2.5 and PM10 in air of Dhaka remains almost

constant for the last 10 years. The concentration of PM2.5 and PM10 in Gazipur is higher than that of Dhaka in

winter period. Brick kiln emission and long range transports are the particulate matter sources those increase the

particulate matter in Gazipur compared to Dhaka. Although the government has taken several steps including

introducing CNG driven vehicles but there are no effective change in PM concentration. So initiatives have to be

taken to control the PM emission from brick kilns, which will give positive impact on the air quality of these

cities.

ACKNOWLEDGEMENTS

The authors thankfully acknowledge the Chemistry Division of Atomic Energy Centre, Dhaka for providing lab

facilities and the CASE Project of the Department of Environment to give permission for sampling at CAMS-2

and CAMS-4 sites.

REFERENCES

1. K. Ram, M. M. Sarin and P. Hegde, Atmos. Environ.(UK), 42, 6785-6796 (2008)

2. A. Salam, H. Bauer, K. Kassin, S. M. Ullah and H. Puxbaum, Atmos. Environ.(UK), 37, 2517-

2528 (2003)

3. R. Rangarajan, M. M. Sarin and A. K. Sudheer, J. Geophy. Res. (USA), 112 (2007)

4. Bilkis A. Begum, K. Roy, F. Islam, A. Salm and Philip K. Hopke, J. Bang. Aca. Sci, 36(2),

241-250 (2012)

5. Bilkis A. Begum, Eugene Kim, Swapan K. Biswas, and Philip K. Hopke, Atmos.

Environ.(UK), 38, 3025-3038 (2004)

6. Bilkis A. Begum, Swapan K. Biswas, Eugene Kim, Philip K. Hopke and M. Khaliquzzaman,

J. Air and Waste Management Assoc., 55, 227-240 (2005)

7. B. A. Begum, S. K. Biswas, E. Kim, P. K. Hopke and M. Khaliquzzaman, J. Air and Waste

Management Association 55, 227-233 (2005). 8. R. W. Baldauf, D. D. Lane and G. A. Marotz, Environmental Monitoring and Assessment, 66, 63-70

(2001). 9. B. A. Begum, S. Akhter, L. Sarker and S. K. Biswas, Nucl. Sci. and Applications, 15, 36-42 (2006)

10. S. K. Biswas, S. A. Tarafdar, A. Islam, M. Khaliquzzaman, H. Tervahattu and K. Kupiainen,

Bangladesh. J. Air and Waste Management Association 53,1355-1361(2003).

11. www.CASE.moef.gov.bd

Page 149



particulate matter concentrations in the air of … 93.pdfparticulate matter concentrations in the...

Documents