Enclosure (3) to COMDTINST 4454.1
Alternate Low Enhanced I/M programs are required in the following areas:
Attainment and marginal or moderate nonattainment area with an
urbanized population of 200,000 or more, based on the 1990
Carbon Monoxide Moderate nonattainment area with an urbanized population of
200,000 or more, based on the 1990 census.
EPA will soon propose a more flexible low enhanced I/M program for affected areas with less
that 200,000 population. This standard will not require extensive emission test networks like
those discussed in Part II.A.2 below.
Basic I/M programs are required in the following areas:
Marginal and moderate nonattainment areas that were part of an
approved SIP in 1990.
Carbon Monoxide Moderate nonattainment areas with a design value of 12.7 ppm or
less and having a 1980 census-defined urbanized area population of
200,000 or more.
Vehicles Covered by the I/M Program
The I/M requirements apply to government owned/leased fleet vehicles as well as to vehicles
operated by employees (civilian, military, and contractor personnel) on a federal installation.
These requirements may apply even if the vehicle is registered in another state.
States will not receive credit from EPA for emissions reductions from self-certified fleet I/M
testing data. Because of this