This report summarizes the combined analysis of photochemical modeling results and Classification and Regression Tree (CART) analysis results for selected areas along the Gulf Coast. The objective of this analysis was to use the Classification and Regression Tree (CART) results developed as part of the MMS-sponsored data synthesis study (Volume III of this report) to assess the frequency of occurrence of the conditions that lead to impacts of emissions from oil-and-gas-related sources located within the Outer Continental Shelf (OCS) region on 8-hour ozone concentrations at onshore locations, based on photochemical modeling results using the 2005 Gulfwide emission inventory (Haney et al., 2008).