· Trucks, buses and light commercial vehicles major polluting vehicles

· Stricter emission control norms helped control pollution to some extent

· Latest technology in automobiles can reduce air pollution

BANGALORE: With more than 21 lakh vehicles on the city roads, it was bound to happen. Air quality has been deteriorating and oxygen content going down in some parts of Bangalore.

The mobile monitoring teams of the Karnataka State Pollution Control Board found this happening in areas around schools, colleges and hospitals, indicating an alarming trend.

In Yeshwantpur, one of the most polluted areas, average readings during 2003-04 indicated oxygen content of 3.4 per cent per unit of air monitored. The nitrogen dioxide content was 46.2 per cent, sulphur dioxide 4.6 per cent, carbon dioxide 4.8 per cent and suspended particle matter (SPM) was 147.9. All these showed marginal to appreciable increase over the previous year.

Automobile emissions cause the most air pollution. The major polluting vehicles are trucks, buses and light commercial vehicles, all using diesel. Other studies suggest that if air quality has not become worse, it could be due to stricter emission control norms right from the manufacturing stage, more use of unleaded petrol and low-sulphur diesel. The ban on commercial vehicles older than 15 years running within the city may have helped.

A TERI study suggests that technological developments in automobiles such as the use of three-way catalysts, catalytic converters in cars and better traffic management can substantially reduce air pollution. While more buses may mean less private vehicles on the roads, the effect on air quality may be reduced the fact that buses run on diesel, a source of nitrogen dioxide and sulphur dioxide. One way out can be for buses to run on compressed natural gas (CNG) as in Delhi. A less expensive way can be by fitting buses with particulate traps to reduce emissions, the study suggests.

While respiratory disorders are directly linked to air pollution, there can be other ailments that may take years to develop. Sulphur dioxide inhaled over a long period can cause heart disease by reducing oxygen content in the blood. The toxic effects of lead pollution, especially among young children, are well known. Diesel exhaust can over the years lead to lung cancer. While many in Bangalore are complaining about the increase in cases of asthma and respiratory allergies, more serious ailments are waiting to happen. The silver lining in the cloud is that automobile manufacturers are in a position to prevent this happening.