Wednesday, April 13, 2011

Dhaka, the Dusty City (Norwegian Embassy)

This fall, a three-year institutional collaboration was established between Norwegian Institute for Air Research (NILU) and the Department of Environment in Bangladesh. With support from Norway, the goal is to improve local expertise in air quality monitoring and planning in one of the world's most densely populated cities. To determine where to place the permanent monitoring system, and to get an idea of the current air quality, a delegation from NILU recently traveled to Bangladesh to conduct an initial screening study in Dhaka.

During the winter season, Dhaka is probably the most polluted city in the world, says NILU scientist Scott Randall following his visit.

Like an Industrial Site

Together with local researchers, he measured the concentration of sulfur dioxide, nitrogen dioxide, ozone, as well as small and large dust particles in the air. The high concentration of dust particles surprised the researchers.

Also see impact of brick kiln emissions on Dhaka's air quality.

At this time of year, we had anticipated that the dust levels would be high, but it was higher than we expected. To be in a city - these are some of the highest values we have seen, says Scott Randall.

On the balcony of the Royal Norwegian Embassy in Dhaka, the researchers were able to measure dust concentrations over a period of 24 hours. The results showed values that exceeded three times the legal limit for air pollution in the United States and Bangladesh, and nearly five times the limit in the EU and Norway.

We may have seen these kinds of results before - for example on a industrial site or near a desert where the wind blows the sand around - but not in a city with people, says Randall, who is quick to point out that the results are based on individual measurements, and that there is a need for continuous air monitoring to get more accurate results.

The day we measured could potentially have been the worst day in the worst part of the year, he explains.
From Petrol to CNG
Lack of rain in the winter season, open air burning of waste, regional weather conditions, and discharges from the 1,100 brick kins that surround the city are the main sources of pollution in Dhaka, according to Randall. Due to the Bangladeshi Government’s efforts to promote compressed natural gas (CNG), traffic is merely a secondary source for pollution in Dhaka today.

It's impressive to see the number of cars that run on CNG, and how a country is able to mobilize in this way within a short decade, says Randall.

Pollution: A Public Health Issue
Air pollution costs Bangladesh dearly, both in dollars and lives. At the turn of the century the World Bank estimated that the costs associated with pollution in Dhaka is approximately 800 million USD every year and 15,000 human lives. The pollution is especially harmfull for children, the elderly and people with asthma. With the project in Bangladesh, NILU aims to strengthen the local expertise on health problems related to air pollution.

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