Technology Transfer Network / NAAQS
Ozone and Carbon Monoxide - Air Quality Data Update Fact Sheet
Note: EPA no longer updates this information, but it may be useful as a reference or resource.
Following is a brief summary of EPA's 1992 air quality update for ozone and carbon monoxide nonattainment areas. Ozone (O3):As required by the Clean Air Act Amendments (CAAA) of 1990, EPA designated as "nonattainment" 98 areas in 1991 that did not meet the National Ambient Air Quality Standard for ground- level ozone (a primary constituent of smog). These areas were classified as Marginal, Moderate, Serious, Severe, or Extreme nonattainment areas based on air quality monitoring data. Since that listing, EPA has redesignated four of these areas to attainment; Greensboro-Winston Salem-High Point, NC, Kansas City, KS-MO, Knoxville, TN and Cherokee County, SC. Unclassified and transitional nonattainment areas are not included in these totals. EPA has set the ozone standard at 0.12 parts per million (ppm) daily maximum 1-hour average concentration not to be exceeded more than once per year on average. Compliance with the ozone standard is judged on the basis of the most recent three years with complete monitoring data. The ozone standard is met when the average estimated exceedances of the ozone standard is less than or equal to 1.0. Today's list updates air quality monitoring data for the three year period, 1990-92. During this current three year period, 42 of the remaining 94 nonattainment areas had average estimated exceedance rates less than or equal to 1.0. These 42 areas meeting the ozone standard include 27 of the 40 Marginal areas and 15 of the 32 Moderate areas. EPA is looking to resolve data issues affecting the air quality status of several additional cities noted on the accompanying tables. Carbon Monoxide (CO): Of the 42 nonattainment areas that were designated as nonattainment for carbon monoxide, all of these areas were classified as Moderate nonattainment areas except Los Angeles, which was classified as Serious. Syracuse, NY is the first classified CO nonattainment area to be redesignated as an attainment area. The unclassified CO nonattainment areas are not included in these totals. EPA's National Ambient Air Quality Standard for carbon monoxide is 9 parts per million (ppm) 8-hour nonoverlapping average concentration not to be exceeded more than once per year. The CO standard is met at a site when there are fewer than two exceedances for the two most recent calendar years, with complete air quality monitoring data. During this current two year period, 21 of the 41 nonattainment areas had less than 2 exceedances in both years, 1991 and 1992. Today's listing does not mean that those areas meeting the National Ambient Air Quality Standards during the last three years will automatically be redesignated to attainment. The Clean Air Act Amendments of 1990 state that an area can be redesignated to attainment if the following conditions are met: (1) the area has complete air quality data meeting the national air quality standards, (2) the area has a fully approved State Implementation Plan meeting Clean Air Act requirements, (3) the area has an approved maintenance plan, including a contingency plan, showing attainment for 10 years, (4) the improvement in air quality is due to permanent and enforceable reductions in emissions, and (5) all applicable Clean Air Act requirements have been met. OZONE FINDINGS ( 94 Nonattainment areas) 42 of 94 Ozone (O3) Nonattainment Areas have complete ozone air quality monitoring data meeting the Ozone National Ambient Air Quality Standards (NAAQS) during the period 1990-92. 27 of 40 Marginal Areas Albany, NY Allentown, PA Altoona, PA Buffalo, NY Canton, OH Columbus, OH Edmonson County, KY Erie, PA Evansville, IN Greenbrier, WV Harrisburg, PA Indianapolis, IN Jefferson County, NY Jersey County, IL Johnstown, PA Lancaster, PA Lexington, KY Memphis, TN Norfolk, VA Owensboro, KY Paducah, KY Scranton, PA South Bend, IN Tampa, FL Walworth County, WI York, PA Youngstown, OH-PA 15 of 32 Moderate Areas Charlotte, NC Charleston, WV Dayton, OH Detroit, MI Kewaunee County, WI Lewiston, ME Miami, FL Monterey, CA Parkersburg, WV Pittsburgh, PA Raleigh-Durham, NC Reading, PA Richmond, VA Salt Lake City, UT Toledo, OH CARBON MONOXIDE FINDINGS ( 41 Nonattainment areas) 21 of 41 Carbon Monoxide (CO) Nonattainment Areas have complete carbon monoxide air quality monitoring data meeting CO National Ambient Air Quality Standards (NAAQS) during the period 1991-92. Baltimore Boston, MA Chico, CA Cleveland, OH Colorado Springs, CO Duluth, MN Fresno, CA Grants Pass, OR Hartford, CT Klamath Falls, OR Lake Tahoe S. Shore, CA Longmont, CO Memphis, TN Modesto, CA Ogden, UT Philadelphia-Camden, PA-NJ Raleigh-Durham, NC San Diego, CA Seattle-Tacoma, WA Washington, DC Winston Salem, NC