Steps
to taken to combat pollution
The
Clean Air Act of 1970 gave EPA broad authority to regulate
motor vehicle pollution, and the Agency's emission control
policies have become progressively more stringent since
the early 1970's.
EPA standards dictate how much pollution autos may emit
but automakers decide how to achieve the pollution limits.
The emission reductions of the 1970's came about because
of fundamental improvements in engine design, plus the addition
of charcoal canisters to collect hydrocarbon vapors and
exhaust gas recirculation valves to reduce nitrogen oxides.
The advent of "first generation" catalytic converters
in 1975 significantly reduced hydrocarbon and carbon monoxide
emissions. The use of converters provided a huge indirect
benefit as well. Because lead inactivates the catalyst,
1975 saw the widespread introduction of unleaded gasoline.
This resulted in dramatic reductions in ambient lead levels
and alleviated many serious environmental and human health
concerns associated with lead pollution.
The
next major milestone in vehicle emission control technology
came in 1980-81. In response to tighter standards, manufacturers
equipped new cars with even more sophisticated emission
control systems. These systems generally include a "three-way"
catalyst (which converts carbon monoxide and hydrocarbons
to carbon dioxide and water, and also helps reduce nitrogen
oxides to elemental nitrogen and oxygen), plus an on-board
computer and oxygen sensor. This equipment helps optimize
the efficiency of the catalytic converter.
Vehicle
emissions are being further reduced by provisions of the
1990 Clean Air Act. Mobile source provisions include even
tighter tailpipe standards, increased durability, improved
control of evaporative emissions, and computerized diagnostic
systems that identify malfunctioning emission controls.
What Has Emission Control
Meant for Air Quality?
Efforts by government and industry since 1970 have greatly
reduced typical vehicle emissions. In those same years,
however, the number of miles we drive has more than doubled.
 The
increase in travel has offset much of the emission control
progress.
The net result is a modest reduction in each automotive
pollutant except lead, for which aggregate emissions have
dropped by more than 95 percent.
With ozone continuing to present a persistent urban air
pollution problem, future vehicle emission control programs
will emphasize hydrocarbon and nitrogen oxide reductions.
Carbon monoxide control will remain critical in many cities,
and limits on vehicle-generated carbon dioxide may become
important in the future.
Steps taken in India
In an effort to check automobile pollution in this country
the government of India has fitement made it mandatory the
fitement of catalytic convertors for all new passenger cars
registered in the four metros namely Delhi, Mumbai, Chennai
and Calcutta from 1st April, 1995. Moreover from 1st September
1997 the sale of unleaded petrol has been stopped in Delhi.
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