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Dhaka’s air pollution level alarmingly high

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Ferdous Ara

Six air-quality monitoring stations will start operation in January 2012 to keep records of the levels of air pollution in different parts of the country under the Clean Air and Sustainable Environment project.

Construction work of the stations in Dhaka, Chittagong, Sylhet, Barisal, Narayanganj and Gazipur are in full swing, officials at the department of environment said adding that the project would cost Tk 12 crore.

In Dhaka, one of the most populous cities of the world, where air pollution is believed to be alarmingly high, the monitoring station is being set up on the premises of the Institute of Mass Communication’s premises on Darus Salam Road at Mirpur.

World Health Organisation sources said the air in Dhaka was among the most polluted compared to the air quality in other mega cities of the world.

Previous index indicate that air quality in Dhaka remain somewhat bearable in April-October but starts deteriorating in November which continues till March every year, the project officer Golam Sarwar said.

The standard of air quality, ascertained by the department of environment for Bangladesh, allows 65 microgram particles of 2.5 micron and 150 microgram particles of 10 micron for every cubic metre of air, but during winter the air pollution level in Dhaka city goes alarmingly high with concentration of up to 274 microgram of fine particulate matters per cubic metre, said officials.

Of the other monitoring stations around Dhaka, one is being set up on the premises of Narayanganj 200-bed hospital and the other in Gazipur municipality graveyard area, the officials said.

In the port city of Chittagong, an air quality monitoring station is being set up on the land of Chittagong City Coprporation at Agrabad.

In Sylhet, a station is being set up at the Red Crescent Bhaban while the Barisal station is located at the DoE.

An Indian company has supplied the equipment manufactured in the US for the six air quality monitoring stations which are in addition to five such stations in operation in

Dhaka, Chittagong, Rajshahi and Khulna under the Air Quality Management Project since 2002, sources said.

Of the existing five stations, one located in the Jatiya Sangsad Bhaban area in Dhaka and one in Khulna have become inoperative and need replacement or overhaul, the sources added.

DoE officials said the existing station in Dhaka would be replaced and the one at Khulna would be modernised to make the plants capable of monitoring all pollutants.

Experts say dry soil conditions, low relative humidity, scanty rainfall and low northwesterly winds are the reasons for deterioration in air quality during winter.

National Asthma Centre project director Rashedul Hasan said that air pollution was a major cause of respiratory problems reported in the urban areas of the country.

Excessive pollution may cause premature birth and weaken the immunity system of small children who are most exposed to pollution, doctors said.

Particulate matter with diameters less than 10µm can penetrate deep into the lungs and affect respiratory and cardiovascular systems, they added.

Technical consultant of air quality monitoring Swapan Kumar Biswas

told New Age that during winter, brick-kilns contribute 40 per cent to

air pollution, releasing in the air huge particulate substance from coal they use as fuel.

Other possible sources of air pollution cited in a study include re-suspension of road dust from traffic, open burning of materials like leather and tyre, and industrial sources such as cement manufacturing and metal melting, said Swapan Kumar.

Last ten years’ data indicates that gaseous pollutants in general do not exceed the standard of air quality in Bangladesh, he said.

Concentration of sulphur dioxide and nitrogen dioxide over Dhaka was found far exceeding the permissible air quality grade set by the WHO and much higher than that in world’s other big cities such as Cairo, Ho Chi Minh City and Dakar where similar screening studies were conducted, the officials added.

The percentage of deadly ozone in Dhaka is, however, lower than that in Ho Chi Minh City, said the air

pollution study conducted by the DoE and the Norwegian Institute for Air Research (Norsk institutt for luftforskning – NILU) in connection with the Clean Air and Sustainability Project.

The screening study conducted in Dhaka in January 31-February 15, 2011 was mainly aimed at gaining an overview of the background concentrations and the spatial distribution of the air pollution in the Dhaka area.

In addition, the study examined satellite mapping data to get a general regional picture of nitrogen dioxide and particulate matter concentrations

and found that spatial patterns of nitrogen dioxide over Bangladesh exhibited a distinct hotspot over Dhaka.

The study also found that the annual average tropospheric nitrogen dioxide levels of Dhaka increased by approximately 75 per cent between 2003 and 2010.

Geographical distribution of sulphur dioxide shows that concentrations are the highest along

the River Buriganga and surrounding areas where hundreds of smaller industrial units as well as some large brick-kilns were located.


Source: newage



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