Abstract

The population of Dhaka, the capital of Bangladesh, grew at an annual rate of 6.4 percent, from 7.3 million to 11.4 million between 1992 and 1999. During the same period, the vehicle population grew even faster, at an estimated 8.9 percent per year. Air quality in Dhaka has continued to deteriorate in recent years. Because there are no major industries that may otherwise act as significant sources of emissions, much of the air pollution in Dhaka can reasonably be ascribed to the transport sector.

The most serious pollutant of concern in Dhaka is respirable and fine particulate matter. These particles enter the respiratory tract, reaching deep into the lungs, and have been demonstrated in a large number of studies to be linked to respiratory and other illnesses and to premature deaths. The ambient concentrations of respirable and fine particulate matter in Dhaka are two to three times higher than the air quality standards set in the United States and other countries.

Two important sources of fine particulate matter in Dhaka are diesel-powered vehicles and two-stroke engine gasoline vehicles. Among the latter, commercially operated three-wheel taxis (the so-called "baby-taxis") are estimated to account for more than one-third of the total number of kilometers traveled by all vehicles. Particulate emissions from baby-taxis are high partly because of incorrect use of lubricant. Specifically, drivers tend to use excess lubricant of the wrong type, called straight mineral oil. Because of their significant contribution to particulate emissions, this program has focused on emission reduction measures targeting baby-taxis.