Environmental Engineering Reference
In-Depth Information
today's cars are equipped with oxygen sensors, fuel injection, and comput-
erized engine management systems that keep the fuel-air ratio within pre-
cise limits.The reduction of automotive emissions also has required the use
of other technologies such as exhaust gas recirculation (EGR) devices and
vapor recovery systems for the vehicle's fuel tank. Finally, since catalytic
converters are quickly destroyed by lead, that additive (which was used to
allow engines to have higher compression ratios) has been removed from
gasoline, which has had the additional benefit of reducing the presence of
a highly toxic element. Today's engines are vastly more complicated and
sophisticated than the ones found under the hoods of the cars of a few
decades ago. Given the demands for cleaner air, the continued use of the
internal-combustion engine, a nineteenth-century invention, now requires
a host of technologies developed in the late twentieth century.
KEEPING CARS CLEAN
Emissions-control devices have made a major contribution to cleaner air,
but their effectiveness depends on their working properly. As was noted
above, federal law requires that anti-pollution devices have to maintain their
effectiveness for 100,000 miles. But this mandate is of value only if there is
some way to ensure that the vehicle population remains in compliance.
Although emissions standards are set by the federal government, the
enforcement of these standards is the responsibility of individual states.The
federal government, however, is able to retain some control over the process
by threatening to withhold highway funds from states deemed to have inad-
equate testing procedures.
The 1990 amendments to the Clean Air Act required that testing proce-
dures had to simulate actual driving conditions. The place where the pro-
cedure was performed was left up to the individual states. The federal
government has favored a network of facilities that do nothing but testing,
but this has been strongly resisted by owners of gas stations and repair shops
who perform emissions testing as an adjunct to their other services. The
problem with this arrangement is that the presence of a large number of
facilities makes it difficult to inspect the equipment and personnel per-
forming the tests.There is also an inherent conflict of interest when enter-
prises are in the business of making repairs in addition to conducting
emissions tests.
