Table 7-5: Montana Air Quality Nonattainment Areas for Carbon Monoxide (CO)

Table 7-5: Montana Air Quality Nonattainment Areas for Carbon Monoxide (CO)

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County Area Nonattainment in year Redesignation to attainment Classification Part or whole county Population (2000)
Cascade Great Falls 95 96 97 98 99 00 01 NA Not classified Part 56,885
Missoula Missoula 95 96 97 98 99 00 01 NA Moderate <= 12.7ppm Part 52,356
Yellowstone Billings 95 96 97 98 99 00 01 NA Not classified Part 91,232

KEY: NA = not applicable; ppm = parts per million.

NOTES: Nonattainment areas do not meet the national primary or secondary ambient air quality standard for the specified pollutant. Nonattainment areas are classified based on design values: Serious = an area with a design value of 16.5 ppm and above; Moderate = an area with a design value of 9.1 up to 16.4 ppm.

SOURCE: U.S. Environmental Protection Agency, Green Book, available at http://www.epa.gov/oar/oaqps/greenbk/anay.html as of Apr. 20, 2002.