Hurricane Katrina came ashore at Louisiana on August 29, 2005, causing destruction, challenges to industrial operations, and significant population changes in the State's two largest cities of New Orleans and Baton Rouge. This paper will provide detailed analyses of the ambient ozone and precursor (i.e. nitrogen oxides and volatile organic compounds) monitoring data collected by the Louisiana Department of Environmental Quality (LDEQ) in both New Orleans and Baton Rouge before and after Hurricane Katrina. The analyses will cover: (1) a comparison of the last two years (2006 and 2007) of the photochemical monitoring data with long-term trends data, including discussion of any significant changes in ambient ozone and precursor concentrations in New Orleans and Baton Rouge after the landfall of Hurricane Katrina; (2) how Louisiana's two largest cities currently compare to the U.S. 8-hour ozone National Ambient Air Quality Standard (NAAQS); and (3) a preview of how the two cities might fare if the U.S. 8-hour ozone NAAQS is lowered in the future per the July 11, 2007, proposed rule in the Federal Register.