Catalytic converters are supposed to clean up car exhaust and prevent air pollution, but new research shows that they are polluting the atmosphere instead. Italian and French researchers have found dangerous heavy metals from converters far away from their sources, in remote regions of Greenland.
"The fact that we found the metals in Greenland means that it's a global problem. It's not just close to the cities or the highways," says Carlo Barbante, a chemist at the University of Venice.
"The have broken new ground," says Seth Dunn, of the Worldwatch Institute, a Washington environmental group. "The implications could be very significant in terms of human health."
Heavy metals have been proved to be dangerous to human health. Workers who refine platinum, one of the metals used in the converters, suffer from high levels of severe asthma.
Catalytic converters use platinum, palladium and rhodium to convert hydrocarbons, carbon monoxide and nitrogen oxides into less dangerous emissions. But the study found that exhausts from fast-moving cars erode the catalytic converters, causing them to eject microscopic particles that contain the heavy metals.
The U.S., Canada and Japan introduced catalytic converters in the mid-1970s and European cars began using them in the early 1990s. Barbante and his team extracted ice cores in Greenland dating from 1969 to 1988 and from 1991 to 1995.
They found that concentrations of the metals in the ice rose steadily since 1976. The ratio of platinum to rhodium resembles the ratio of these metals in car exhausts. This suggests that the pollution comes from automobiles.
Scientists believe the concentrations of these pollutants in the air of big cities are still too low to create a significant health risk. But the metals, especially palladium, can accumulate in plants and animals and enter the food chain.
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