Several of my friends have recently purchased scooters. They are thrilled that they are now doing something good for the environment. They point to the 90 miles they will now get for each gallon of gasoline burned.
Despite the good gas mileage, not all scooters are good for the environment. Those thinking about purchasing a scooter should be aware that two-stroke engines contribute mightily to pollution. Not all scooters are two-stroke engines, but many of them are. The special Science, Technology and the Future issue of Discover magazine [1] (Dated May, 2008, but not available online) indicates that throughout Asia, scooters with two-stroke engines are producing a vast amount of pollution.
How bad for the environment are two-stroke engine scooters?
Unlike the developed nations’ larger but much more efficient automobiles, which views four-stroke engines, two-stroke vehicles spew great volumes of dangerous hydrocarbons, carbon monoxide and smoke. A single two-stroke engine produces pollution equivalent to that of 30 to 50 four-stroke automobiles. With roughly 100 million motorcycles in Asia–roughly half of them using two-stroke engines–that translates into as much as 2.5 billion cars’ worth of smog.
Two-stroke engines produce a lot of pollution because the fuel-air mixture in them gets contaminated with the engines lubricating oils. Simultaneously the combustion chamber draws in the contaminated mixture as exhaust gases are expelled through an exhaust port. Some of the fuel and oil gets mixed up with the exhaust.
Two-stroke engines show up in many other contexts too, including many machines used for yard work. For instance, most gas burning lawnmowers using two-stroke engines. How much pollution do gas-powered lawn mowers cause? Boulder and County News [2]has some shocking answers:
Traditional gas-powered lawn mowers are responsible for 5 percent of the nation’s air pollution, according to the Environmental Protection Agency, which recently created emission regulations for small engines like those that lawn mowers use. One gas mower running for an hour emits the same amount of pollutants as eight new cars driving 55 mph for the same amount of time, according to the Union of Concerned Scientists.
This is a good reason to consider using a push mower without a gasoline engine [3] if you have a small to medium sized yard (here are more lawn mower stats from the EPA [4]). Today’s push mowers are much smaller and lighter than the push mowers used by your grandparents. It’s really a good option for a lot of reasons, including a reduction in both air pollution and noise pollution.
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