B.
Areas Covered by the I/M Program
The I/M program requirements must be implemented in certain carbon monoxide and ozone
nonattainment areas. Refer to enclosure (1) for a list of Coast Guard areas affected.
The data used to classify an area's air quality status is referred to as the design value and is
measured in parts per million (ppm). There are five nonattainment classifications based on
design values as shown in the following table:
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DESIGN VALUE
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_
_
_
_
_
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_ Marginal_ Moderate_ Serious_ Severe_ Extreme |
|
_ (ppm) _ (ppm) _ (ppm) _ (ppm)_ (ppm) |
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_
_
_
_
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_
_
_
_
_
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_
_
_
_
_
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_ 0.121- _ 0.138- _ 0.160- _ 0.180-_ >0.280 |
| Ozone
_ 0.138 _ 0.160 _ 0.180 _ 0.280 _
|
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_
_
_
_
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_
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_
_
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_
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_
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| Carbon _
_
_
_
_
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| Monoxide _ --- _ 9.1-16.4_ =>16.5 _ --- _ --- |
|
_
_
_
_
_
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|================================================================|
The type of emission testing required, in decreasing order of stringency, (high enhanced,
alternate low enhanced, or basic - see descriptions below) depends on EPA's classification of
an area's nonattainment design values:
High Enhanced I/M programs are required in the following areas:
Ozone Transport
Areas where EPA has reason to believe that the interstate transport
Regions (OTR)
of air pollutants from one or more states contributes significantly to
a violation of a standard in one or more other states. There is one
OTR in the U.S. at present, which includes Washington D.C., and
all or parts of the following States: CT, DE, ME, MD, VA, MA,
NH, NJ, NY, PA, RI, and VT. For any Metropolitan Statistical
Area (MSA) of over 100,000 population located within the OTR,
high enhanced I/M is required, regardless of that area's attainment
classification.
Ozone
Serious, severe, and extreme areas with urbanized populations of
nonattainment
200,000 or more, based on the 1990 census.
Carbon Monoxide Moderate or serious nonattainment areas with a design value
greater than 12.7 ppm and having a 1980 census-defined urbanized
area population of 200,000 or more, shall implement high enhanced
I/M in the 1990 census-defined urbanized area.
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