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.