Technology Transfer Network / NAAQS
Ozone Implementation

Table 1. List of original nonattainment areas not meeting 1-hr NAAQS in 1996-98

Note: EPA no longer updates this information, but it may be useful as a reference or resource.

State	Nonattainment Area ⁽¹⁾	O₃ Design Value ⁽²⁾ (ppm)	Avg. Expected Exceedance Rate⁽³⁾
		O₃ Design Value ⁽²⁾ (ppm)	Avg. Expected Exceedance Rate⁽³⁾
		1996-98	1996-98
GA	Atlanta NA Area	0.146	7.0
MD	Baltimore NA Area	0.141	4.1
LA	Baton Rouge NA Area	0.127	1.4
TX	Beaumont-Port Arthur NA Area	0.133	2.0
AL	Birmingham NA Area	0.128	2.1
NC	Charlotte-Gastonia NA Area	0.131	1.7
WI	Chicago-Gary-Lake County NA Area	0.136	1.7
TX	Dallas-Fort Worth NA Area	0.135	2.0
TX	El Paso NA Area	0.123	1.1
CT	Greater Connecticut NA Area	0.139	2.7
TX	Houston-Galveston-Brazoria NA	0.196	8.6
WV	Huntington-Ashland NA Area	0.129	2.0
MD	Kent County and Queen Anne's Co.	0.126	1.7
TN	Knoxville NA Area	0.134	3.7
CA	Los Angeles South Coast Air Basin	0.217	50.1
IN	Louisville NA Area	0.130	2.1
WI	Manitowoc Co, WI NA Area	0.128	1.7
WI	Milwaukee-Racine NA Area	0.136	1.7
TN	Nashville NA Area	0.127	2.0
NY	New York-N. New Jersey-Long Island, NY-NJ-CT	0.139	3.4
MD	Philadelphia-Wilmington-Trenton, PA-NJ-DE	0.152	3.1
AZ	Phoenix NA Area⁽⁴⁾	0.126	1.3
OR	Portland-Vancouver AQMA NA Area	0.133	1.3
VA	Richmond-Petersburg NA Area	0.125	1.3
CA	Sacramento Metro NA Area	0.148	5.6
CA	San Diego NA Area	0.135	3.7
CA	San Francisco-Bay NA Area	0.138	4.7
CA	San Joaquin Valley NA Area	0.161	17.2
CA	Santa Barbara - Santa Maria - Lompoc, CA	0.130	1.8
WI	Sheboygan NA Area	0.130	1.3
CA	Southeast Desert Modified AQMD, CA	0.170	25.3
MA	Springfield (W. Mass) NA Area	0.128	1.3
MO	St. Louis NA Area	0.131	1.3
DE	Sussex Co NA Area, DE	0.125	1.3
CA	Ventura Co NA Area, CA	0.144	6.4
MD	Washington, DC-MD-VA NA Area	0.129	3.2

Notes:

1. Designations and classifications for ozone nonattainment areas as published in the Federal Register, 40 CFR Part 81. Unclassified and transitional nonattainment areas are not included in Table 1.

2. The updated air quality design value is estimated for the 1996-98 period using all air quality data reported to EPA's Aerometric Information Retrieval System (AIRS). The computation procedures follow EPA guidance for calculating design values (Laxton Memorandum, June 18, 1990). For sites with three complete years of monitoring data, the air quality design value is the fourth highest daily maximum 1-hour ozone concentration, because the standard allows one exceedance per year on average. It is important to note that the 1990 Clean Air Act Amendments required that nonattainment areas be classified on the basis of the design value at the time the Amendments were passed, generally the 1987-89 period was used.

3. The level of the 1-hour ozone Ambient Air Quality standard is 0.12 parts per million (ppm) daily maximum 1-hour average concentration not to be exceeded more than once per year on average. The average estimated number of exceedances column shows the number of days the 0.12 ppm 1-hour ozone standard was exceeded on average at the site recording the highest updated air quality value. This computation is performed after adjustment for any missing sampling days during the 3-year period, 1996-98.

4. Special purpose monitoring data not available in AIRS but cited in "FINAL Technical Support Document for the Notice of Final Rulemaking on Finding of Failure to Attain and Denial of Attainment Date Extension for Ozone in the Phoenix (Arizona) Metropolitan Area", October 27, 1997.

Table 2. Additional counties failing to meet the 1-hour ozone NAAQS in 1996-98

State	County (Area)	O₃ Design Value ⁽¹⁾ (ppm)	Avg. Expected Exceedance Rate ⁽²⁾
State	County (Area)	1996-98	1996-98
CA	Amador Co. (adjacent to Sacramento)	0.128	2.5
CA	Calaveras Co. (adjacent to Stockton)	0.130	1.7
CA	Imperial Co. (Calexico, CA)	0.143	1.9
IN	Hamilton Co. (adjacent to Indianapolis)	0.125	1.3
IN	La Porte Co. (adjacent to Chicago)	0.128	1.3
MI	Berrien Co. (Benton Harbor, MI)	0.125	1.4
MS	De Soto Co. (adjacent to Memphis)	0.131	1.3
NC	Rowan Co. (adjacent to Charlotte)	0.126	1.3
TN	Hamilton Co. (Chattanooga)⁽³⁾	0.125	1.3
TN	Jefferson Co. (adjacent to Knoxville)	0.126	2.0
TX	Gregg Co. (Longview-Marshall)	0.128	2.0

Notes:

1. The updated air quality design value is estimated for the 1996-98 period using all air quality data reported to EPA's Aerometric Information Retrieval System (AIRS). The computation procedures follow EPA guidance for calculating design values (Laxton Memorandum, June 18, 1990). For sites with three complete years of monitoring data, the air quality design value is the fourth highest daily maximum 1-hour ozone concentration, because the standard allows one exceedance per year on average. It is important to note that the 1990 Clean Air Act Amendments required that nonattainment areas be classified on the basis of the design value at the time the Amendments were passed, generally the 1987-89 period was used.

2. The level of the 1-hour ozone Ambient Air Quality standard is 0.12 parts per million (ppm) daily maximum 1-hour average concentration not to be exceeded more than once per year on average. The average estimated number of exceedances column shows the number of days the 0.12 ppm 1-hour ozone standard was exceeded on average at the site recording the highest updated air quality value. This computation is performed after adjustment for any missing sampling days during the 3-year period, 1996-98.

3. An exceedance of the level of the 1-hour ozone standard in 1998, and the possible influence of the Central American fires, is the subject of an ongoing analysis and discussion by Hamilton County, Tennessee and EPA.

Table 1. List of original nonattainment areas not meeting 1-hr NAAQS in 1996-98

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