Enclosure (3) to COMDTINST 4454.1
COAST GUARD INSPECTION AND MAINTENANCE (I/M)
GUIDANCE
I.
Background
In November 1990, Congress amended the Clean Air Act (CAA) in order to further reduce air
pollution in the United States. The new amendments created more comprehensive regulatory
requirements for air emissions from mobile sources. A three point strategy for achieving
reductions in motor vehicle emissions is being pursued by the Environmental Protection
Agency (EPA) which includes:
development and manufacture of cleaner vehicles
production of cleaner fuels
implementation of more stringent inspection and maintenance
(I/M) testing
Newer vehicles produce significantly less air pollution than older vehicles, and because
current vehicle fleets and privately-owned vehicles are being driven for longer periods, I/M
testing ranks as a highly important strategy to achieve more immediate reductions in ozone
and carbon monoxide (CO) to improve air quality. I/M program requirements must be
incorporated into the State
Implementation Plans (SIPs) which each affected state was required to submit to EPA for
approval. Several states have yet to submit their plans.
A.
Purpose of I/M Program
The I/M program was developed to monitor whether vehicle engines and emissions control
devices are working properly. Even though newer vehicles are designed to meet stringent
standards, lack of maintenance or malfunctioning emissions controls can cause excessive
pollution. Older vehicles are more likely to pollute more because of malfunctioning
emissions controls. The average passenger vehicle in the United States is seven years old,
and EPA estimates that 55% of these vehicles are high emitters of ozone precursors
(hydrocarbons) and CO. Because excessive polluting vehicles are not obvious, inspections
must be performed to identify those vehicles needing repairs to their emissions controls.
Periodic vehicle inspections and required repairs are intended to encourage proper vehicle
maintenance and discourage tampering.
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