The EPA provides leadership to State/local/tribal agencies on the selection and use of models in regulatory settings through national modeling guidance, the Model Clearinghouse, and conferences and workshops. This site provides the following links for guidance and other related support:

Permit Modeling Guidance - Provides access to guidance which provides recommendations on modeling techniques to be applied for State Implementation Plan (SIP) revisions for existing sources and New Source Review (NSR) and Prevention of Significant Deterioration (PSD) programs.

SIP Attainment Demonstration Guidance - Provides access to the modeling guidance documents for Ozone, PM, and Regional Haze for SIP attainment demonstrations.

Other Applicable Guidance - Provides access to miscellaneous guidance other than for permit modeling or SIP attainment demonstrations.

Model Clearinghouse - Provides access to an electronic database system designed to help record information about referrals and discussions from EPA Regional Offices involving the interpretation of modeling guidance for specific regulatory applications.

State and EPA Regional Modeling Contacts - Provides a listing of State and EPA Regional modeling contacts.