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EPA is under a Court order to complete the remaining SO2 designations for the rest of the country in three additional rounds. On March 20, 2015 the EPA released an updated guidance for 1-hr SO2 area designations. The two options included are compliance through dispersion modeling or ambient monitoring. Of these two options, dispersion modeling is the fastest and most cost effective one to characterize SO2 air quality. However, this compliance demonstration can be challenging given that AERMOD tends to produce overly conservative concentration estimates. Source characterization techniques and probabilistic techniques may be used to achieve compliance with the 1-hour NAAQS. Three advanced methods discussed: 1) Equivalent Building Dimensions (EBD); 2) Emission Variability Processor (EMVAP); 3) 50th Percentile Background Concentrations.