United States
Environmental Protection
Agency
Office of
Public Awareness (A-107)
Washington DC 20460
Tuning Down
Auto Air Pollution
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For sale by the Superintendent of Documents, U.S. Government Printing Office
Washington, D.C. 20402
Stock No. 055-000-00164-2
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Introduction
In every metropolitan area
of the United States
people are caught in an
automotive dilemma.
The comfort and
convenience of the private
automobile, operating on
an extensive network of fine
highways, has scattered
urban populations all
over the landscape. In the
process, public transit
has been severely curtailed
or avoided. This excessive
reliance on the automobile
is poisoning the air we
breathe.
Despite the energy crisis,
America's geography,
population patterns, and
life styles dictate that
the automobile will continue
to play a dominant role in
our transportation system
for a long time. Since the
damage to human health
from automotive
pollution is painfully
real, we must do as much
as we can to diminish
its impact.
There are many things we
can do—improved
public transportation, car
pooling, cleaner, more
efficient automobiles, better
driving habits—to cut
down both on the overall
use of the automobile
and to make individual cars
less of a pollution
problem. The purpose of
this booklet is to
discuss one of these: the
proper maintenance of
automobiles so that they
retain throughout their
lifetime the pollution
control capability that was
built into them.
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The Automotive
Pollutants
Photochemical oxidants:
ozone, peroxyacyl nitrate,
formaldehyde, acrolein,
nitrogen peroxide, and
organic peroxides—are
produced by a complex
series of chemical
reactions initiated when
hydrocarbons and nitrogen
oxide emissions from
automobiles are
exposed to sunlight.
This type of pollution first
gained attention in the
1940's as the main cause
of smog in Los Angeles.
Since then photochemical
smog has become common
in many cities.
Photochemical oxidants can
affect the lungs and eyes.
They may cause respiratory
irritation and even
changes in lung function.
They may result in eye
irritation with the familiar
symptoms of tears and
inflammation. At certain
concentrations they
have been shown to impair
the performances of
athletes and to affect
persons with asthma.
Ozone, the main
constitutent of
photochemical smog, is
a severe irritant to all
mucous membranes and
its main health effects
are on the respiratory
system. It is virtually
intolerable at levels of
1 part per million.
At considerably lower
concentrations (.1
to .2 ppm)—levels which
frequently occur in the
summer air of many
American cities—ozone,
in conjunction with
other photochemical
oxidants, causes a variety
of health effects that
are aggravated when people
are active outdoors.
This is the hazard that
keeps the elderly, the very
young, and those with
respiratory problems
virtually trapped indoors
during air pollution
alerts that can extend
for many days.
Carbon Monoxide: Carbon
monoxide is a colorless,
odorless, tasteless gas
commonly found in our
urban areas in
concentrations that can
be harmful to people.
It is a by-product of
combustion and the
automobile is the largest
single source of this
pollutant.
Carbon monoxide is inhaled
through the lungs and
enters the blood stream
by combining with
hemoglobin, the substance
that carries oxygen to
the cells. Hemoglobin
combines much more
readily with carbon
monoxide than with oxygen.
The result is that the
amount of oxygen being
distributed throughout the
body by the blood
stream is reduced in the
presence of carbon
monoxide and this can
have a profound impact on
our health.
Carbon monoxide also
impairs heart function by
weakening the contractions
which pump blood to
various parts of the body.
The effect of this on a
healthy person is to reduce
significantly his ability
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Building
a Clean Car
to perform manual tasks,
such as working,
jogging, and walking. But
in a patient with heart
disease, who is unable to
compensate for the
decrease in oxygen, it can
be a life-threatening
situation. A person who
has a heart attack is more
likely to die in the
presence of heavy carbon
monoxide air pollution
than if the attack
occurred in clean air. And
carbon monoxide is also
harmful to persons
who have lung disease,
anemia, or cerebral-
vascular diseases.
Carbon monoxide also
affects the central nervous
system at relatively
low-concentrations. Tests
of automobile drivers—
after exposure to carbon
monoxide—show slower
reaction times in response
to braking signals.
In enacting the various
clean air laws, the Congress
left it up to the expertise
of the auto manufacturers
to determine how best
to reduce pollutant levels.
Without controls,
gasoline-powered cars
emit pollutants from
the fuel tank, carburetor,
crankcase, and engine
exhaust. The manufacturers
have used a variety of
devices and techniques to
achieve emission control.
The U.S. Environmental
Protection Agency's job is
to see that the automobiles
and light trucks designed
and produced by the
manufacturers meet the
emission levels set by
Congress. EPA monitors
manufacturers'
performance at three
stages: prototype,
production, and in use.
At the prototype stage,
EPA evaluates prototype
models for every engine
configuration in terms of
their capability to meet
applicable standards.
In cases where more than
one model shares the
same engine, EPA usually
tests only the heavier
model on the assumption
that if the heaviest
model meets the emissions
levels, the lighter ones
will too.
The second testing is done
on the production lines.
A sample of cars is
selected at random. If all
pass, production continues.
If one or more fail, the
testing continues until
a pattern can be
established. If the pattern
indicates a significant
failure rate, production
must be stopped until
modifications can be made
to bring the vehicles
into line with the legal
emission levels.
The law requires
manufacturers to provide
buyers with a warranty
that vehicles are (1)
designed, built, and
equipped so as to conform
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Keeping
a Car Clean
with emission standards
at the time of sale and
(2) free of defects in
material and workmanship
which cause them to fail to
conform for a period of five
years, or 50,000 miles.
The third stage of the
Federal motor vehicle
control program testing of
cars in actual use, is
meant to check for
conformance to this
requirement. Private firms
are hired to spot-check
particular models suspected
of having emission
problems. Owners' lists are
compiled from
registration records in
various cities and letters
are written asking
them to bring in their
cars for testing. Since the
test—similar to the
ones made at the
production line—takes
morethan 12 hours,
owners are offered
premiums, such as free
savings bonds, if they bring
their cars in. If the cars fail
even though they have been
properly maintained and
used, the manufacturer
may be required to recall
all cars of that model for
basic corrective repairs of
design or manufacturing.
The random checking of
suspect models has a
positive, though limited
effect. But it does not
address an important
problem: the best designed,
best made emission
control systems may give
poor emission-control
performances if they are
damaged or improperly
adjusted. A car that has no
emission problem in
its first months may have
severe problems a year
later. A number of surveys
made since 1974
indicate that practically
all cars which are not
systematically checked and
maintained, develop
serious emission
problems.
Based on early estimates,
it was projected that
cars of the 1975 model
year would continue to meet
the Federal emission
standards throughout their
useful lives. These
projections were too
optimistic. By the end of
their first year, the
1975 cars in regular use
were exceeding acceptable
levels for both carbon
monoxide (CO) and
hydrocarbons (HC), and
careful calculations
indicated that their
emission levels would
continue to rise in
subsequent years. Cars
which were not given
systematic maintenance
were 50 percent above the
acceptable CO level at
the end of the first year,
and projections
indicated that they would
probably be emitting
at twice the acceptable level
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by the end of the tenth
year. The hydrocarbons
projections, though
less stark, were still
ominous. (See Fig. 1)
However, the sharp rises
in emission levels occurred
only when cars were not
properly maintained.
Two additional tests were
made on 1973 model-year
cars which had been driven
an average of 15,000
miles. One was on cars
which had been given
ordinary maintenance; the
other was on cars
which had been maintained
according to the
manufacturer's
specifications. The latter
had substantially lower
emission levels for both
carbon monoxide and
hydrocarbons. (See Fig. 2). '
Thus, both these tests
and the spot checking of
cars in use clearly
indicate an important
conclusion: well-maintained
cars can minimize a
community's pollution
problem.
Figure 2:
Significance of
Maintenance
Ratio of
Emissions
Divided by
Standards
Figure 1: Emissions Related to
Standards (Model Year
1975 Cars)
77 1978 1979 1980 1981 1982 1983 1984 1985
4.07
3.03
1,249
Cars
Proper Maintenance and Tuned
140
Cars
As Found Condition
1973 Standard
(3.4 g/mi)
Hydrocarbons
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Inspection/
Maintenance
(I/M):
Anticipated
Problems and
Solutions
37.3
1,249
Cars
Proper Maintenance and
Tuned
140
Cars
As Found Condition
Carbon Monoxide
53.5
1 973 Standard
(39 g/mi.)
One very good way to
ensure that cars are in fact
well-maintained is to
establish a program for the
required inspection of all
vehicles and then to require
maintenance of those
vehicles which emit
pollution in excess of
appropriate levels. New
Jersey was the first state to
give such an I / M program a
significant trial. In the first
phase it was voluntary,
in the second, mandatory.
Before it began there
were a number of
unanswered questions
concerning both practicality
and techniques:
Could an adequate
inspection be made—one
which would not cost much
or take too long?
Would available commercial
service centers be able
to make necessary
adjustments?
Would they be able to make
them at reasonable costs?
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An Effective
Short Test
What Can You Do
with a Dirty Car?
The Federal procedure test
is time-consuming and
expensive. Cars in daily use
are put in a "cold
soak"—12 hours under a
controlled temperature—
before testing. The test
checks emissions at
different simulated speeds.
If hundreds of thousands
of cars were to be tested in
a single jurisdiction, the
Federal test clearly is
impractical.
A short test was needed—
one which could be made in
minutes—and a number
of such tests were
developed. Some tested
idling motors only, some
tested cars at a variety
of simulated speeds. When
followed by corrective
repairs to vehicles failing
the best, CO and HC
emissions decreased
significantly. The most
widely used test—the idle
as used in New Jersey—
deserves particular
attention since it is the
simplest and least
expensive. In one survey
of the New Jersey program,
9,070 cars were tested
and adjusted; the average
reduction in carbon
monoxide emissions at idle
was 27.3 percent and in
hydrocarbons, 26.5
percent.
Short tests are not a
perfect substitute for the
full Federal Test Procedure.
Manufactures who must
redesign faulty models will
still need the Federal tests,
which produce extensive
and precise information.
Large volume, short
tests, however, need only
to distinguish between
"clean" and "dirty" cars.
Cut-off points can be
established which measure
emissions in terms of
the concentration of
pollutants. Cars that have
emissions over the cut-offs
fail. With proper cut-offs,
short tests can predict with
good accuracy whether
a particular car would pass
the long Federal test.
Short tests are workable
and mass inspection can
spot polluting cars. But, can
the needed adjustments
or repairs indicated by short
tests be made easily
and cheaply?
Tests in New Jersey,
Arizona, and Oregon show
that most failing cars need
only carburetor adjustments
and motor tune-ups, which
are well within the capacity
of most commercial
service garages. The New
Jersey experience also
indicates that commercial
service stations can rise
to meet the demand. During
the voluntary phase of
the program, over 40
percent of the failing cars
failed again after
repairs or adjustments.
Within three months after
the program became
mandatory, the retesting
failure rate had fallen
to about 18 percent. Many
stations in New Jersey
now guarantee that the cars
they correct will pass the
second time around.
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Costs
Most I/M adjustments
needed are simple
and relatively inexpensive.
In Oregon less than
10 percent of the failing
cars require repair
work costing more than
$50. In Arizona this
number was 14 percent,
and in New Jersey,
22 percent. Most repairs
were even cheaper. In
Oregon, 70 percent cost
less than $10 and the
average was below $20. In
Arizona, 66 percent cost
less than $25 and the
average was under $35,
The slightly higher costs in
New Jersey were partly
because the test there is
less stringent and the
failing cars are logically
likely to be in need of
greater repairs.
I/M programs do cost
money. Whenever a car
fails—and most will sooner
or later—its owner has
to pay for adjustments or
repairs. There is
substantial evidence,
however, that adjustment
costs are often balanced by
fuel savings because I/M
maintained cars run more
efficiently and use less
gasoline.
A study conducted by the
State of California focused
on cars that had gone
through I/M compared
with a control fleet that had
not. The I/M cars had
higher maintenance
costs—on an average
$15.41 higher in a year—
but they also showed
substantial reductions in
fuel costs—with an
average saving of $15.83;
a net saving per car
of 42 cents.
Another study conducted
by EPA showed the added
average maintenance
costs for an I / M fleet of
$9.60 were precisely
balanced by an average
$9.60 saving in fuel.
These tests were not
conclusive but they did
strongly suggest that the
out-of-pocket cost of
I/M is slight. There is also
a possible long-term
saving. A car that goes
through an I/M program
each year may have a
longer span of usefulness
and need fewer major
repairs.
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The Catalysts
and Repairs
Long Term
Questions
Studies have shown that
cars equipped with
catalysts and air pumps
have considerably lower
emission levels than those
without them. Catalysts
work—but are they more
expensive to maintain?
Preliminary data indicate
that they a re not, that
repairs and adjustments
to catalyst equipped cars,
excluding replacement of
the catalyst, are not
significantly more expensive
than for non-catalyst cars.
Catalyst-equipped cars
respond to the same kind
of repairs as cars without
them. That is, if a car
fails to meet emission
standards, repairs are
usually either simple
carburetor adjustments or
tune-ups. Catching a severe
malfunction in the fuel
and combustion system has
the additional benefit of
protecting the catalyst.
The initial questions about
I/M have positive answers.
• Short tests are effective.
• Repairs to "dirty" cars
are generally
inexpensive.
• I/M programs do reduce
emissions significantly.
However, other questions
remain. How rapidly does
an inspected and adjusted
car deteriorate? (Or, to
put it another way, how
frequently must they
be re-inspected and
re-adjusted?)
It was first assumed that
the value of I/M
adjustments would last
no more than a year, that in
that year the emission
reduction would average
out to one-half of the
initial reduction.The only
major study yet made on
deterioration suggests that
this estimate was too low.
The test for the California
Air Resources Board in
1975 was made over a
full year. The tested cars
included models from
1968 to 1974, reflecting
the actual variety in
use in the State.
One group was put through
an I / M process and then
tested (but not adjusted or
repaired after the initial
adjustments) at intervals
of 1, 3, 6, 9 and 12 months.
The control group was
tested (but not adjusted
or repaired) at the
beginning and end of the
year. Emissions from
the I/M group started
lower and climbed
more rapidly. They did
not, however, rise to
either the final levels of the
control group nor their
own levels before I / M. The
positive effect of I/M
had lasted longer than
the anticipated year. I/M
produced a year-long
average emission reduction
of 70 percent of the
initial reduction. (See Fig.
3.)
I/M has clear, positive
results. Cars properly
inspected and adjusted put
out fewer pollutants.
Relatively new cars which
fail I/M improve
significantly after
adjustment.
10
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I 0
But what about older cars? 1.5
• Do emission levels
inevitably deteriorate as
time goes by?
• Is a ten-year-old car
certain to be a heavy
polluter in spite of the
owner's best efforts at
proper maintenance?
No one will know the
absolute answers to these
questions for several
years, but analyses indicate
the long term
emission-reduction
effectiveness of proper
maintenance. A car's
pollution level is probably
going to be higher in
its tenth year than in its
first, but if it has had
an annual inspection, with
maintenance as needed,
the tenth-year performance
is going to be significantly
better than it would
have been without I/M.
Though we lack enough
information to be
sure, catalyst cars to date
appear to be following
the same long-range
pattern as non-catalyst
cars, especially with
respect to CO.
Ratio of
Emissions
Divided by
Standards
0
Months
2.0
4.0
6.0
8.0
10.0
12.0
Figure 3:
Effect of I/M on Deterioration of Controls
11
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I/M Cut-Off Points
and the
Older Car
Since older cars have less
extensive emission control
equipment than newer
cars, I / M cut-offs for them
have generally been
made less stringent. Thus,
older cars have been
just as able to pass I/M
tests as newer cars.
Moreover, the best
available evidence indicates
that although polluting
levels do rise, properly
maintained older cars
can still pass the same test
year after year. Data
from New Jersey show that
pollution levels tend to
stabilize. Old cars, when
properly maintained,
can pass standard tests
(See Fig. 4). In 1972,
24.1 percent of all the old
cars inspected (in use
five or more years) failed.
Four years later only
18.4 percent of the cars
of the same model years
failed. Clearly there were
fewer of them and the worst
offenders had been
junked, but it is also clear
that older cars, if
properly cared for, can pass
the I/M standards.
Model Year
of Car Tested
1976
1975
1974
1973
1972
1971
1970
1969
1968
1967 and
and Older
1972
—
—
—
—
10.8
23.6
30.8
18.0
26.7
24.1
Calendar Year
When Tested
1973
—
—
—
8.7
14.4
21.1
28.7
15.5
19.8
19.1
1974
—
—
7.4
15.4
18.8
27.8
30.8
20.3
23.9
21.5
1975
—
16.7
14.5
16.3
19.7
26.4
29.6
21 4
24.6
19.2
1976
—
—
13.8
17 1
21.7
25.9
32.4
22.4
27 1
18.4
Figure 4:
Percent of Cars Failing Tests in New Jersey
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Are All
I/M Programs
Equal?
Auto
Maintenance:
Voluntary or
Mandatory?
I/M programs are designed
and administered by
individual States. The goals
are the same—each
seeks a significant and
permanent reduction in the
pollutants in the air—
but the standards
are diverse.
Still, all good I/M programs
have mucn in common.
They must:
• Apply to all cars and
light trucks, public and
private;
• Be repetitive (formal
inspections should occur
at least once a year;
• Re-test failed vehicles
and remove chronic
failures from the streets;
• Check inspection
equipment regularly
and routinely for
accuracy.
Inspections can be
administered in several
different ways.
Administration is easiest
when inspections are
done at centralized
locations. States may or
may not wish to hire a
contractor to perform this
service. The other
alternative is for
commercial service stations
to provide the testing.
Convenience to drivers
is increased, but the
State must devote much
effort to monitoring
and licensing for this
alternative to be effective.
States can and should
design I/M programs which
reflect their own needs
and limitations. I/M cut-off
points can be more or
less stringent. They should
be demanding but
realistic; a program which
has less than maximum
standards can still be
effective.
Each community—whether
it be city, county,
metropolitan area, or
State—will have to decide
whether its air pollution
situation can be handled
through a program
in which car owners are
encouraged to keep
their vehicles properly
maintained or whether the
situation requires a
mandatory inspection and
maintenance program.
An important point to
remember is that where
communities must
lower ozone and carbon
monoxide to healthful
levels there will be a
need to lower automotive
emissions. Since
inspect ion/maintenance
not only reduces emissions
substantially but offers
significant fuel savings
also, I/M may well be
the most desirable
transportation pollutant
control strategies.
*
U.S. GOVERNMENT PRINTING OFFICE : 197! O—247-556
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