The air pollution from cutting grass for an hour with a gasoline-powered lawn mower is about the same as that from a 100-mile automobile ride, according to a new study from Sweden, which recommends using catalytic converters on mowers. The report is the first to compare lawn mower pollution with auto mileage, according to the researchers.
The recommendation is reported in the June 1 issue of Environmental Science & Technology, a peer-reviewed journal of the American Chemical Society, the world's largest scientific society.
One significant pollutant from mowers is polycyclic aromatic hydrocarbons, or PAHs, said Roger Westerholm, Ph.D., an assistant professor at Stockholm University in Stockholm, Sweden. He claims such emissions, similar for both riding and push mowers, can be cut more than 80 percent using a catalytic converter like those used in automobiles.
Westerholm found that the worst case of lawn mower PAH emissions totaled more than 4,000 micrograms per hour using unleaded fuel without a catalytic converter. Average emissions dropped to nearly 800 micrograms over the same time period with the addition of a catalytic converter, he said. Some PAHs, including a few in lawn mower emissions, are classified as probable carcinogens by the U.S. Centers for Disease Control and Prevention.
"Obviously, if catalysts will become mandatory on lawn mower engines, and possibly other small engines as well, a significant reduction of exhaust components will be achieved," Westerholm said.
In 1998, the U.S. Environmental Protection Agency issued the so-called "Phase I" rules, which mandated a 32 percent reduction in emissions for small "non-road" engines. This affects all engines less than 25 horsepower produced after 1997, including mowers, leaf blowers and chain saws. According to an EPA study prior to the Clean Air Act of 1990, small engines from lawn and garden equipment make up nearly 9 percent of some types of air pollution. While current mowers
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American Chemical Society