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- Nonattainment
- any area that does not meet (or that contributes
to ambient air quality in a nearby area that does not meet) the
national primary or secondary ambient air quality standard for
the pollutant.
- Attainment
- any area (other than an area identified in clause
(i)) that meets the national primary or secondary ambient air
quality standard for the pollutant.
- Unclassifiable
- any area that cannot be classified on the basis
of available information as meeting or not meeting the national
primary or secondary ambient air quality standard for the
pollutant.
(See
section 107(d)1 of the Clean Air Act.)
- Extreme
- Area has a design value of 0.187 ppm and above.
- Severe 17
- Area has a design value of 0.127 up to but not including 0.187 ppm
- Severe 15
- Area has a design value of 0.120 up to but not including 0.127 ppm
- Serious
- Area has a design value of 0.107 up to but not including 0.120 ppm.
- Moderate
- Area has a design value of 0.092 up to but not including 0.107 ppm.
- Marginal
- Area has a design value of 0.085 up to but not including 0.092 ppm.
- Extreme
- Area has a design value of 0.280 ppm and above.
- Severe 17
- Area has a design value of 0.190 up to 0.280 ppm and
has 17 years to attain.
- Severe 15
- Area has a design value of 0.180 up to 0.190 ppm and
has 15 years to attain.
- Serious
- Area has a design value of 0.160 up to 0.180 ppm.
- Moderate
- Area has a design value of 0.138 up to 0.160 ppm.
- Marginal
- Area has a design value of 0.121 up to 0.138 ppm.
- Submarginal
- Kansas City was the only area classified
submarginal, but it has been redesignated attainment. This
category includes areas that violate the ozone standard and have
a design value of less than 0.121 parts per million. This occurs
when there is not a complete set of data so that the estimated
design value is higher than the ozone standard exceedance rate of
1.0 per year even though the estimated design value is less than
the level of the standard.
- Section 185A (Previously called Transitional)
- an area designated as an ozone
nonattainment area as of the date of enactment of the Clean Air
Act Amendments of 1990 has not violated the national primary ambient air
quality standard for ozone for the 36-month period commencing on January 1, 1987,
and ending on December 31, 1989. Twelve areas were classified transitional
in 1991. (See section 185A of the Clean Air Act.)
- Incomplete (or No) Data
- an area designated as an ozone
nonattainment area as of the date of enactment of the Clean Air
Act Amendments of 1990 and did not have sufficient data to
determine if it is meeting or is not meeting the ozone standard.
(See
section 181 of the Clean Air Act.)
- Serious
- Area has a design value of 16.5 ppm and above.
- Moderate
- Area has a design value of 9.1 up to 16.4 ppm.
- Not Classified
- an area designated as an carbon monoxide
nonattainment area as of the date of enactment of the Clean Air
Act Amendments of 1990 and did not have sufficient data to
determine if it is meeting or is not meeting the carbon monoxide standard.
(See
section 186 of the Clean Air Act.)
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