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PM is decreasing in Dhaka
Air Quality Management Project (AQMP) estimates that about 15% PM10 and 25% PM2.5 has been reduced in annual average (2002 vs. 2003)

Particulate matter is the main pollutant of concern for Dhaka and has been identified to be extremely harmful to public health. Two-stroke engine driven three-wheelers, commonly known as baby taxis, were the main culprit for this particulate air pollution. Prior to September 2002 a large number of two stroke three-wheelers were used to ply in Dhaka and the number of this class of vehicles was estimated to be between 30 and 65 thousand. Emission inventory calculations showed that these vehicles contribute to about 40% of the vehicular air pollution for the particulate matter.

After a long period of stakeholder discussions and awareness raising, a phased withdrawal of two-stroke three-wheelers was carried out in Dhaka, with the final phase occurring on the 31st of December 2002. As a result one would expect dramatic change in air pollution situation in Dhaka. Concentration of particulate matter should be deceased in 2003 compared to 2002. From the data available in the Continuous Air Monitoring Station (CAMS) it is clear that the concentrations of PM10 and PM2.5 in 2003 are lower than 2002 particularly November and December (Monthly Average). Comparison of annual average of PM10 and PM2.5 will give more precise assessment of the impact of removal of baby taxi on particulate matter concentration in Dhaka.

The improvement in air quality was observed immediately after removal of this baby taxi. Reduction of almost 40% particulate matter was found by comparing the last week data of December 2002 with the first week data of January 2003. This study was based on very short period of data. However, over time emissions from replacement diesel vehicles have been diminished some of the initial gains. But still we have some gain when we compare the annual average of 2002 and 2003. Air Quality Management Project (AQMP) has estimated that about 15% PM10 and 25% PM2.5 has been reduced in annual average due to this excellent policy intervention. The annual average of PM10 in 2002 was 114µg/m3 which comes down to 97µg/m3 in 2003. In the case of PM2.5 the annual average was 69 µg/m3 in 2002 and 52 µg/m3 in 2003.

However, the concentration of annual averages is still much higher than the proposed standard (PM10 - 50µg/m3 and PM2.5 - 15 µg/m3).

Posted by:
Muntaseer Billah
Air Quality Management Project (AQMP)
Department of Environment
Dhaka, Bangladesh

Extracted from Listserv archives 11 January 2004

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