United States
Environmental Protection
Agency
Office of
Public Affairs (A-107)
Washington DC 20460
June 1984
v>EPA I/M Fact Sheet
I/M = Cleaner Air
Motor vehicle inspection/maintenance (I/M) programs are now operating in a
number of jurisdictions throughout the United States in keeping with
provisions of the Clean Air Act. Some of the common questions car owners
have about I/M programs are answered in this fact sheet.
What is the purpose of I/M programs?
I/M works to lower air pollution levels by requiring
periodic inspection of the emissions systems of cars
and light trucks and maintenance, when necessary, to
keep those systems functioning properly.
How does I/M work?
Inspections generally are carried out by
state-controlled facilities or garages authorized by the
state to do the checks. While the vehicle is running,
the probe of an exhaust gas analyzer is placed in the
tailpipe. This analyzer checks the amounts of carbon
•monoxide and hydrocarbons in the exhaust.
What if I fail the test?
In most cases, all a car needs is an emissions tune-up
which reduces air pollution and can improve the
vehicle's performance and gas mileage. Testing
programs in several states have shown that about 15
to 30 percent of cars require maintenance work, with
typical costs ranging from $18 to $35. The most
common repairs required are: (1) carburetor
adjustments, (2) air filter replacement, (3) idle speed
adjustment, (4) choke adjustments, (5) spark plug
replacement. Some repairs may be covered under the
car's emissions warranty.
What pollutants come from car exhausts?
Cars emit three major polluting gases—carbon
monoxide, hydrocarbons, and oxides of nitrogen.
Carbon monoxide goes directly to the bloodstream
and reduces the amount of oxygen in the blood. In
large quantities, it is deadly. In smaller amounts,
carbon monoxide can cause dizziness, loss of appetite,
nausea, blurred vision and headaches.
Hydrocarbons and oxides of nitrogen react together
in the presence of sunlight to form smog, which is
made up of ozone and other photochemical oxidants.
Ozone can cause difficulty in breathing, chest pain,
;hest and nasal congestion, coughing, eye irritation,
nausea and headaches.
The people most susceptible to high levels of carbon
monoxide and ozone are infants and small children,
elderly people, those with respiratory and heart
ailments, and active people such as joggers.
More than 90 percent of the carbon monoxide and
one-third of the hydrocarbons in the atmosphere come
from motor vehicles. The primary causes of high
emission levels are maladjustments and inadequate
maintenance.
Apart from the tailpipe check, what does an
inspection cover?
Some states include an emissions control tampering
check as part of the I/M program. Data collected by
EPA since 1978 show that one out of five vehicles has
had at least one part of its emissions control system
disabled. In some I/M programs, vehicles are checked
for air pollution control equipment that was required
for that particular model and year. The check could
include inspection of some or all of the following:
catalytic converter, fuel inlet restrictor, air pump,
positive crankcase ventilation, evaporative canister,
and exhaust gas recirculation valve.
Don't cars run better without this control equipment?
No. Cars are now designed to perform most efficiently
when the emissions control system is fully operational
and correctly adjusted. Mileage is better and long-term
maintenance costs are reduced. Fuel switching—using
leaded gasoline in cars designed for unleaded
gas—can ruin emissions control systems, run up
maintenance costs and force the replacement of
expensive parts.
Isn't I/M unfair to people who own older cars?
Older cars are not expected to meet the same
standards as newer models with sophisticated
emissions controls. The pass/fail standards for each
model year are set to be within the design capacity of
the automobile. In addition, some states set cost limits
to avoid penalizing people who drive older cars which
might require expensive repairs (such as ring or valve
jobs) to meet emissions standards.
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Why must we have I/M programs?
The Clean Air Act required states to meet certain air
quality standards by December 31, 1982, but Congress
also provided that areas with severe pollution
problems could be granted extensions to 1987 if they
agreed to initiate I/M programs. Implementation of I/M
was emphasized because the payoff in emissions
reductions is significantly greater than can be achieved
through alternative control strategies. In addition,
programs already in operation had demonstrated that
I/M was feasible, reasonable in cost, and acceptable to
the public.
Where are I/M programs in operation now?
Listed below are all urbanized areas currently running an
I/M program, including areas under 200,000 population.
The latter areas are indicated with asterisks. The list *
also includes counties which have all or a part of theii
population within the urbanized area boundary, as
defined by the 1970 census. A particular I/M program
may include counties which do not appear on this list
because they are outside the urban area. Also, a
program may exclude one or more counties which are
part of the urbanized area. Where this occurs, the
excluded counties appear on this list in parentheses.
ARIZONA
Phoenix:
Maricopa Co.
Tucson:
Pima Co.
CALIFORNIA
South Coast Air Basin:
Los Angeles Co.
Orange Co.
Oxnard - Ventura
Thousand Oaks:
Ventura Co.
San Francisco/Oakland:
Alameda Co.
Contra Costa Co.
Marin Co.
Napa Co.
San Francisco Co.
San Mateo Co.
Solano Co.
San Bernardino/Riverside:
San Bernardino Co.
Riverside Co.
San Diego:
San Diego Co.
San Jose:
Santa Clara Co.
Sacramento:
Placer Co.
Sacramento Co.
Yolo Co.
COLORADO
Denver area:
Adams Co.
Arapahoe Co.
Boulder Co.
Jefferson Co.
Colorado Springs:
El Paso Co.
CONNECTICUT
[statewide program]
Hartford:
Hartford Co.
Middlesex Co.
Tolland Co.
New Haven:
New Haven Co.
Bridgeport:
Fairfield Co.
DISTRICT OF COLUMBIA
[tri-state]
DELAWARE
Wilmington:
New Castle Co.
GEORGIA
Atlanta:
Cobb Co.
(Clayton Co.)
DeKalb Co.
Fulton Co.
(Douglass Co.)
(Gwinnett Co.)
INDIANA
Chicago suburbs:
Lake Co.
Porter Co.
Louisville suburbs:
Clark Co.
Floyd Co.
KENTUCKY
Louisville [bi-state]:
Jefferson Co.
MARYLAND
Baltimore:
Anne Arundel Co.
Baltimore Co.
Howard Co.
District of Columbia area:
Montgomery Co.
.Prince Georges Co.
MASSACHUSETTS
[statewide program]
Boston:
Middlesex Co.
Norfolk Co.
Plymouth Co.
Suffolk Co.
Springfield:
Hampshire Co.
Hampden Co.
Worcester:
Worcester Co.
Lawrence:
Essex Co.
MISSOURI
St. Louis area:
St. Charles
St. Louis City
St. Louis Co.
NEVADA
Las Vegas:
Clark Co.
Reno:*
Washoe Co.
NEW JERSEY
[statewide program]
Allentown/Bethletiem/Easton:
Warren Co.
New York City area:
Bergen Co.
Essex Co.
Hudson Co.
Middlesex Co.
Monmouth Co.
Morris Co.
Ocean Co.
Passaic Co.
Somerset Co.
Union Co.
Philadelphia area [bi-state]:
Burlington Co.
Camden Co.
Gloucester Co.
Trenton [bi-state]:
Mercer Co.
Wilmington area [bi-state]:
Salem Co.
NEW YORK
NY metro area [bi-state]:
Bronx Co.
Kings Co.
Nassau Co.
New York Co.
Putnam Co.
Queens Co.
Richmond Co.
Rockland Co.
Suffolk Co.
Westchester Co.
NORTH CAROLINA
Charlotte:
Mecklenburg Co.
OREGON
Portland area [bi-state]:
Multnomah Co.
Clackamas Co.
Washington Co.
(Clark Co., WA)
PENNSYLVANIA
Philadelphia [bi-state]:
Bucks Co.
Chester Co.
Delaware Co.
Montgomery Co.
Philadelphia Co.
Pittsburgh:
Allegheny Co.
Beaver Co.
(Lawrence Co.)
Washington Co.
Westmoreland Co.
Allentown/Bethlehem/Easton:
Lehigh Co.
Northampton Co.
RHODE ISLAND
[statewide program]
Providence:
Bristol Co.
Kent Co.
Providence Co.
Washington Co.
TENNESSEE
Memphis:
Shelby Co.
UTAH
Salt Lake City area:
Davis Co.
VIRGINIA
District of Columbia area:
Arlington Co.
Fairfax Co.
Alexandria City
Fairfax City
Falls Church City
WASHINGTON
Seattle area:
King Co.
(Pierce Co.)
Snohomish Co.
WISCONSIN
Milwaukee:
Milwaukee Co.
Ozaukee Co.
Racine Co.
Washington Co.
Waukesha Co.
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