The two-wheelers have two-stroke engines. Such engines are far less efficient in burning the fuel that is used in the vehicles. The exhaust systems are also less effective at removing pollutants. On the contrary most of the four-wheelers have catalytic converters. Therefore, the exhaust fumes from scooters contain higher levels of the chemicals found in the fuel and oil they use.
The vehicles with two-stroke engine such as two wheelers emit significantly more primary organic aerosols and volatile organic compounds from incomplete burning of the fuel. They also produce significant secondary organic aerosols as gases released from the exhaust react with the air and microscopic particles of soot.
These pollutants increase the risk of heart and lung disease. Older two-stroke vehicles produced reactive oxygen molecules that are known to be potentially harmful for lung health. In recent times there is excessive use of two-wheelers which is deteriorating the air quality to great extent.
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Nilesh is a student of Std. VII and lives in urban area. It takes about an hour to go to the school by bus. He faces the heavy traffic of two wheelers, four wheelers, rickshaws, buses while going to school. He is facing the problem of asthma since last few days, Doctors recommended him to stay away from urban area. Since then, his mother sent him to the village of his maternal uncle, Nilesh saw the heaps of garbage at many places in village. Foul smell of human and animal wastes was present at many places. Blackish water with foul smell was flowing in a stream. He developed some abdominal disease within few days.