International Regulation of Urban Smog Since the 1940s - Air Pollution and Global Warming: History, Science, and Solutions - page 180

lifetime of the source. CAAA70 also required National
Emission Standards for Hazardous Air Pollutants
(NESHAPS) .Hazardous pollutants were defined as
pollutants

Congress, and not the U.S. EPA, set the initial automo-
bile emission standards, but the U.S. EPA was autho-
rized to extend deadlines for autoemission reductions.
The U.S. EPA extended the deadline in 1975 for all
reductions by 1 year in 1973, by a second year in 1974,
and by a third year for THCs and CO(g).
CAAA70 also gave the U.S. EPA authority to set and
revise

to which no ambient air standard is applicable and
that ...causes, or contributes to air pollution which
may be anticipated to result in an increase in mortality
or an increase in serious irreversible, or incapacitating
reversible illness.

...standardsapplicable to the emission of any air pol-
lutant from any class or classes of new motor vehicles
or new motor vehicle engines, which in his judgment
cause, or contribute to, air pollution which may rea-
sonably be anticipated to endanger public health or
welfare. [Section 202(a)(1)]
Thus, the U.S. EPA could regulate additional pollu-
tants from automobile exhaust found to affect health
or welfare and could revise existing emission stan-
dards from motor vehicles. This clause would serve
as the basis for regulating greenhouse gas emissions
from vehicles almost 40 years later, as discussed in
Section 8.1.12.

In 1973, the list of hazardous pollutants included only
asbestos, beryllium, and mercury. By 1984, the list had
been expanded to include benzene, arsenic, coke oven
emissions, vinyl chloride, and radionuclides. CAAA70
also specified that

...each state shall have the primary responsibility for
assuring air quality within the entire geographic area
comprising each state by submitting an implementa-
tion plan for such state which shall specify the man-
ner in which national primary and secondary ambient
air quality standards will be achieved and maintained
within each air quality control region in each state.

Thus, the use of SIPs, which originated with the
Air Quality Control Act of 1967, continued under
CAAA70. CAAA70 required that SIPs address primary
and secondary standards. Through a SIP, each state was
required to set ambient air quality standards at least
as stringent as federal standards, evaluate air quality
in each AQCR within the state, and establish meth-
ods and timetables for improving air quality in each
AQCR to meet state standards. The SIP was required to
address approval procedures for new pollution sources
and methods of reducing pollution from existing
sources. Once submitted, a SIP required U.S. EPA
approval; otherwise, the U.S. EPA had the power to
take control of the state's air pollution program.
CAAA70 further required that the U.S. EPA develop
aircraft emission standards; expand the number of
AQCRs; and establish tough fines and criminal penalties
for violations of SIPs, emission standards, and perfor-
mance standards. It also permitted citizen's suits

8.1.7. Catalytic Converters
In direct response to automobile emission regula-
tions instigated by CAAA70, the catalytic converter ,
an important automobile emission control technology,
wasdeveloped by 1975. Automobile engines produce
incompletely combusted NO x (g), CO(g), and THCs,
as well as completely combusted CO 2 (g) and H 2 O(g).
Catalytic converters convert NO x (g) to N 2 (g), CO(g) to
CO 2 (g), and unreacted THCs to CO 2 (g) and H 2 O(g).
Since 1975, three major types of catalytic convert-
ers have been developed: (1) single-bed converters,
(2) dual-bed converters, and (3) single-bed three-way
converters.
A catalyst is a substance that causes or accelerates
a chemical reaction without affecting the substance.
The catalysts in catalytic converters are generally the
noble metals platinum (Pt), palladium (Pd), rhodium
(Rh), ruthenium (Ru), gold (Au), or a combination
of these. These catalysts are applied as a coating over
porous alumina spherical pellets, ceramic honeycombs,
or metallic honeycombs within the converter to increase
the surface area contacting the exhaust. Exhaust gases
travel through the converter with a residence time of
about 50 milliseconds. The use of noble metal cata-
lysts requires the simultaneous use of unleaded fuel
because lead deactivates the catalyst through chemi-
cal reaction. Thus, the catalytic converters forced the
emission reduction of another pollutant, lead .

against any person, including the United States, alleged
to be in violation of emission standards or an order
issued by the administrator.

The national aircraft emission standards set by
CAAA70 were enacted after California set a state stan-
dard in 1969.
CAAA70 required that new automobiles emit 90 per-
cent less THCs and CO(g) in 1975 than in 1970 and
90 percent less NO x (g) in 1976 than in 1971. Thus,