Catalytic Converters
Most cars are sources of pollution, and to keep up with emissions laws
automakers began refining car engines and fuel systems in the 1970s. These
modifications culminated in catalytic converters, which treat exhaust before it
leaves a car's tailpipe, converting toxic combustion by-products such as carbon
and nitrogen monoxides to less-toxic gases. Catalytic converters have been
highly successful in reducing emissions, but substantial increases in the
distances cars and trucks travel on average and in the overall number of
vehicles in use have made up the difference, and cars are still a major cause
of pollution.
