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Support Center for Regulatory Atmospheric Modeling (SCRAM)

Sulfur Dioxide Designations and Implementation Modeling Guidance and Assistance

The information and links provided below are intended to help inform and assist Regional, State, Local, and Tribal modelers with respect to designation and implementation modeling for the 1-hour sulfur dioxide (SO2) National Ambient Air Quality Standard that became effective on June 2, 2010. Examples of State and local SO2 modeling protocols, requests for information (source characterization and emissions data), and modeling input data are provided for illustrative purposes and will be updated as additional information becomes available to the EPA.

Please note that consultation with the appropriate EPA Regional Office must be sought before implementing any of the information contained in the State and local examples that are provided below.

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Sulfur Dioxide (SO2) National Ambient Air Quality Standard:

General Information
Final Revision to Primary NAAQS - June 22, 2010 (PDF)(85 pp, 667 K)

Appendix W (40 CFR Part 51) 1-Hour SO2 Policy Relevant Guidance:

Applicability of Appendix W Modeling Guidance for the 1-hour SO2 NAAQS (PDF)(5 pp, 396 K)
Additional Clarification Regarding Applicability of Appendix W Modeling Guidance for the 1-hour NO2 NAAQS (PDF)(27 pp, 538 K) - Applicable for the 1-hour SO2 NAAQS.

SO2 Designations Modeling Guidance:

This guidance updates and replaces the previous designation guidance for the 2010 SO2 NAAQS, which was issued on March 24, 2011.

SO2 Implementation Modeling Guidance:

Summary of Modeling Guidance for SO2 Implementation - One Pager (PDF)(1 pg, 296 K)
Draft Primary Sulfur Dioxide National Ambient Air Quality Standards Implementation Guidance (PDF) From 9-22-2011
Webinar Presentation - Draft Modeling Guidance for SO2 Implementation (PDF)(37 pp, 840 K)

2011 Regional, State, and Local Modelers' Workshop - SO2 Related Presentations:

The following links exit the site Exit

2011 RSL Modelers' Workshop Website and Agenda

State and Local SO2 Modeling Protocol Examples:

LADCO Modeling Protocol Letter (PDF)(11 pp, 878 K) Exit

State and Local Requests for Information (Source Characterization and Emissions Data) Examples:

Illinois Environmental Protection Agency Template Document (PDF)(2 pp, 16 K)
Indiana Department of Environmental Management Template Document (PDF)(2 pp, 38 K) and Template Spreadsheet (XLS)(39 K)
Oklahoma Department of Environmental Quality Template Document (PDF) (2 pp 13 K)
Texas Commission on Environmental Quality - Special Inventory Request Presentation (PDF) (12 pp 172 K)

SO2 Modeling Input Data:

Meteorological Data - Surface and Upper Air Databases
Monitored SO2 Ambient Concentrations - EPA Air Quality System (AQS)
Source Emissions - EPA National Emission Inventory (NEI) Database

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