Air Quality Improvement


Ozone Levels in 1988 and 1995

Peak ozone levels have generally declined since 1988, but 1995 also recorded high levels. Violations in 1995 were not as severe as in 1988, partly due to emissions controls (e.g., cleaner gasoline), and partly due to differences i n weather.

A very stagnant weather pattern dominated the summer of 1988 in the eastern US. Polluted air was recirculated, leading to repeating severe ozone violations. High temperatures were oppressive and persistent. An extensive drought resulted in dry conditio ns conducive to ozone formation. Peak ozone levels in 1988 were the highest recorded at Mid-Atlantic ozone monitors in the past ten years (Luebehusen, 1996).

Since 1988, peak ozone levels have been lower, but 1995 was again a bad year for ozone. The highest levels of ozone in 1995 occurred in mid-July. Winds at the surface were from the southwest or south, but upper-level winds were from the north or northwe st. Air coming into the Mid-Atlantic Region from the Midwest already contained high levels of ozone and nitrogen oxides.

By July 14, 1995, 37 monitors recorded high levels from Maryland to Massachusetts. On July 15, 36 monitors from Virginia to Connecticut exceeded the standard. On July 16 a cold front from the north cleaned the air in the northern states, but violations persisted in the Baltimore-Washington region until a cold front passed through from the west on July 18 (Ryan et al., 1996).

Sources: WF Ryan, BG Doddridge, RR Dickerson, RM Morales, KA Hallock, KL Civerolo, PT Roberts, DL Blumenthal, J Anderson (1996) "Regional Trace Gas Observations During a High O3 Episode in the Mid-Atlantic Region: A Case Stud y," Draft for submission to the Journal of the Air and Waste Management Administration, October.
Eric Luebehusen, personal communication, February 14, 1996.
WF Ryan, personal communication, April 9, 1997.

Map: Measured Ozone on July 6, 1988 at 1400 EST

Map: Measured Ozone on July 7, 1988 at 1400 EST

Map: Measured Ozone on July 14, 1995 at 1600 EST

Map: Measured Ozone on July 15, 1995 at 1600 EST


Areas that Have Met the Ozone Standard

The federal Clean Air Act provides that when air quality in an ozone nonattainment area has met the standard for a period of three years, the area may be designated as an attainment area rather than a nonattainment area if sufficie nt controls exist to prevent future violations. Several areas in the Mid-Atlantic Region have met the standard, and redesignations have been approved by EPA for some of these areas.

All ozone nonattainment areas in West Virginia have been redesignated as attainment areas. This includes Charleston, Huntington-Ashland (WV-KY), Parkersburg, Boyd County, and Greenbrier County.

North Carolina also has had its three ozone nonattainment areas redesignated to attainment. The Greensboro-Winston Salem-High Point area was the first area in the Mid-Atlantic Region to be redesignated, becoming an attainment area effective in November 1 993. Raleigh-Durham and Charlotte-Gastonia followed in 1994 and 1995, respectively.

Sources: Ozone, Carbon Monoxide, Particulate Matter, Sulfur Dioxide, Lead, Areas Designated Nonattainment, October 17, 1996 (EPA Green Book).


Areas that Have Met Air Quality Standards and Been Redesignated as Attainment

North Carolina

Charlotte-Gastonia


Gaston and Mecklenburg Counties
Previously designated as moderate nonattainment area
Redesignated to Attainment effective July 5, 1995

Greensboro-Winston Salem-High Point

Davidson, Davie, Forsyth, and Guildord Counties
Previously designated as moderate nonattainment area
Redesignated to Attainment effective November 8, 1993

Raleigh-Durham

Durham, Wake, and Granville (Dutchville township part) Counties
Previously designated as moderate nonattainment area
Redesignated to Attainment effective June 17, 1994

West Virginia

Charleston


Kanawha and Putnam Counties
Previously designated as moderate nonattainment area
Redesignated to Attainment effective September 6, 1995

Greenbrier County

Previously designated as marginal nonattainment area
Redesignated to Attainment effective September 18, 1995

Huntington-Ashland, WV-KY

Cabell and Wayne Counties, WV, and Boyd County (part)
Previously designated as moderate nonattainment area
Redesignated to Attainment effective December 21, 1994

Parkersburg

Wood County
Previously designated as moderate nonattainment area
Redesignated to Attainment effective September 6, 1995


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Last revised: 11/17/98