Taiwan Today

Vehicular exhaust is the dominant source of air pollution in Taiwan, accounting for about 55 percent of toxic emissions. In this group, motorcycles that run on two­-stroke engines are the main offenders. “Two-stroke” refers to the number of “steps” necessary to convert fuel into en­ergy. Fewer steps means that fuel is burned less efficiently. Four-stroke engines are therefore more efficient. A two-stroke engine also requires more lubricant than does a four-stroke one. Because of their inefficient operation, two-stroke engines emit more unburned fuel and lubricant into the air. Per kilometer driven, a two-stroke motorcycle emits the same amount of hydrocarbons and carbon monoxide as twelve cars equipped with catalytic converters. And compared to four-stroke engines, they emit more vola­tile organic compounds, toxic chemicals which help cause urban smog. Some 40 percent of Taiwan’s motor vehicles use two-stroke engines.

But motorcycles are not the only cul­prits. Many automobiles in Taiwan are not equipped with catalytic converters, which help reduce toxic emissions in vehicle exhaust. Since 1990, the Environmental Protection Administration (EPA) has required all new cars to be installed with catalytic converters, and in 1991 it set the same requirement for two-stroke motor­cycles. But catalytic converters are not mandatory in cars or motorcycles pur­chased before these years. Moreover, because these converters reduce gas mileage, some people remove them. A 1994 study prepared by National Taiwan University's Department of Public Health found that only about 20 percent of cars on Taiwan's roads were equipped with cata­lytic converters.

Heavy vehicles are to blame as well. More than 90 percent of Taiwan's buses and most trucks use diesel fuel. Diesel fumes have been linked to lung cancer. Aside from requiring that diesel fuel have minimal sulfur content, Taiwan has no other restrictions on diesel-powered buses or trucks.