Support Center for Regulatory Atmospheric Modeling (SCRAM)

State Implementation Plan (SIP) Attainment Demonstration Guidance

The EPA’s Air Quality Modeling Group (AQMG) provides guidance documents to EPA Regional, State, and Tribal air quality management authorities and the general public on how to prepare attainment demonstrations for National Ambient Air Quality Standards (NAAQS) and the Regional Haze Rule using air quality modeling and other relevant technical analyses. These guidance documents are primarily directed at modeling applications in nonattainment areas but are also useful for modeling in maintenance areas or to support other rules or sections of the Clean Air Act. These guidance documents recommend procedures for estimating if a control strategy to reduce pollutant emissions (e.g., ozone precursors) will lead to attainment of the appropriate NAAQS. They also describe how to apply air quality models to generate the predictions later used to see if attainment is shown. The guidance documents are divided into three categories: 8-hour Ozone/Particulate Matter (PM_2.5)/Regional Haze Guidance, PM₁₀ Guidance, and Carbon Monoxide Guidance.

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8-hour Ozone/PM_2.5/Regional Haze Modeling Guidance
Modeling Guidance for Demonstrating Attainment of Air Quality Goals for Ozone, PM_2.5, and Regional Haze (PDF)(205 pp, 2 MB, 11-29-2018, 454-R-18-009) - Final version of the updated Ozone, PM_2.5, and Regional Haze modeling guidance document. Draft Modeling Guidance for Demonstrating Attainment of Air Quality Goals for Ozone, PM_2.5, and Regional Haze (PDF)(214 pp, 3 MB, 12-03-2014) - Draft version of the updated Ozone, PM_2.5, and Regional Haze modeling guidance document. Guidance on the Use of Models and Other Analyses for Demonstrating Attainment of Air Quality Goals for Ozone, PM_2.5, and Regional Haze (PDF)(262 pp, 1 MB, 04-16-2007, 454-B-07-002) - Ozone, PM_2.5, and Regional Haze modeling guidance document. Update to the 24 Hour PM2.5 NAAQS Modeled Attainment Test (PDF)(8 pp, 394 K, 06-28-2011) - Updated version of the 24-hour PM_2.5 attainment test. This new version replaces section 5.2 of the 2007 PM_2.5 modeling guidance (PDF)(262 pp, 1 MB, 04-16-2007, 454-B-07-002). The Software for the Modeled Attainment Test - Community Edition (SMAT-CE) is now available.

8-hour Ozone/PM_2.5/Regional Haze Modeling Guidance

Modeling Guidance for Demonstrating Attainment of Air Quality Goals for Ozone, PM_2.5, and Regional Haze (PDF)(205 pp, 2 MB, 11-29-2018, 454-R-18-009) - Final version of the updated Ozone, PM_2.5, and Regional Haze modeling guidance document.

Draft Modeling Guidance for Demonstrating Attainment of Air Quality Goals for Ozone, PM_2.5, and Regional Haze (PDF)(214 pp, 3 MB, 12-03-2014) - Draft version of the updated Ozone, PM_2.5, and Regional Haze modeling guidance document.

Guidance on the Use of Models and Other Analyses for Demonstrating Attainment of Air Quality Goals for Ozone, PM_2.5, and Regional Haze (PDF)(262 pp, 1 MB, 04-16-2007, 454-B-07-002) - Ozone, PM_2.5, and Regional Haze modeling guidance document.

Update to the 24 Hour PM2.5 NAAQS Modeled Attainment Test (PDF)(8 pp, 394 K, 06-28-2011) - Updated version of the 24-hour PM_2.5 attainment test. This new version replaces section 5.2 of the 2007 PM_2.5 modeling guidance (PDF)(262 pp, 1 MB, 04-16-2007, 454-B-07-002).

The Software for the Modeled Attainment Test - Community Edition (SMAT-CE) is now available.

Supporting Documents - Ozone/PM_2.5/Regional Haze
Fine Particulate Matter (PM_2.5) Precursor Demonstration Guidance(56 pp, 673 K, 05-30-2019, 454-R-19-004) Technical Guidance for Demonstration of Inter-Precursor Trading (IPT) for Ozone in the Nonattainment New Source Review Program (PDF)(38 pp, 11 MB, 05-01-2018, 454-R-18-004) Draft Criteria For Assessing Whether an Ozone Nonattainment Area is Affected by Overwhelming Transport (PDF)(8 pp, 30 K, 06-29-2005) and the Errata Sheet for Draft Criteria: March 28, 2006 (PDF)(1 pg, 10 K, 03-28-2006) Frequently Asked Questions on Implementing the DRAFT 8-Hour Ozone Modeling Guidance to Support Attainment Demonstrations for Early Action Compact (EAC) (PDF)(9 pp, 30 K, 02-23-2004) Guidance for the 1-hour Ozone Nonattainment Areas that Rely on Weight-of-Evidence for Attainment Demonstrations (PDF)(31 pp, 67 K, 03-28-2002) - Mid-Course Review Guidance Guidance for Improving Weight-of-Evidence Through Identification of Additional Emission Reduction Not Modeled (PDF)(10 pp, 192 K, 11-01-1999) Guidance on Use of Modeled Results to Demonstrate Attainment of 1-hr Ozone NAAQS (ZIP)(153 K, 07-29-1996) Guideline for Regulatory Application of the Urban Airshed Model (PDF)(83 pp, 130 K, 07-01-1991)
Note: Information on air quality modeling of individual sources for visibility assessments can be found at: Phase I Guidance: National Park Service (1993): Interagency Workgroup on Air Quality Modeling (IWAQM) Phase 1 Report: Interim Recommendation For Modeling Long Range Transport And Impacts On Regional Visibility (PDF)(105 pp, 2 MB, 04-01-1993, 454-R-93-015). U.S. Environmental Protection Agency, Technical Support Division, Research Triangle Park, North Carolina 27711. U.S. Environmental Protection Agency (1995): Interagency Workgroup on Air Quality Modeling (IWAQM): Assessment of Phase 1 Recommendations Regarding the Use of MESOPUFF II (PDF)(137 pp, 601 K, 12-01-1995, 454-R-95-006). Office of Air Quality Planning and Standards, U.S Environmental Protection Agency, Research Triangle Park, NC 27711. Phase II Guidance: Irwin, J.S., (1998): Interagency Workgroup on Air Quality Modeling (IWAQM) Phase 2 Summary Report and Recommendations for Modeling Long Range Transport Impacts (PDF)(160 pp, 3 MB, 12-01-1998, 454-R-98-019). Office of Air Quality Planning and Standards, Research Triangle Park, NC, 151 pp. (NTIS Accession Number PB 99-121089). Garrison, M., A. Gray, S.T. Rao, M. Scruggs (1999): Peer Review of the Interagency Workgroup On Air Quality Modeling Phase 2 Summary Report And Recommendations For Modeling Long Range Transport Impacts (PDF)(67 pp, 184 K, 01-01-1999). This Report was Compiled by: John S. Irwin Air Policy Support Branch, Atmospheric Sciences Modeling Division U.S. Environmental Protection Agency Research Triangle Park, NC 27711, 64 pp. U.S Environmental Protection Agency (1999): Response To Peer Review Comments of the Interagency Workgroup On Air Quality Modeling Phase 2 Summary Report And Recommendations For Modeling Long Range Transport Impacts (PDF)(4 pp, 13 K, 02-01-1999). U.S. Environmental Protection Agency (2009): Draft Reassessment of the Interagency Workgroup on Air Quality Modeling (IWAQM) Phase 2 Summary Report: Revisions to Phase 2 Recommendations (PDF)(56 pp, 1 MB, 05-27-2009). U.S. Environmental Protection Agency (2012): Documentation of the Evaluation of CALPUFF and Other Long Range Transport Models using Tracer Field Experiment Data (PDF)(247 pp, 8 MB, 05-01-2012, 454-R-12-003). EPA Contract No: EP-D-07-102, Work Assignment No: 4-06.

Supporting Documents - Ozone/PM_2.5/Regional Haze

Fine Particulate Matter (PM_2.5) Precursor Demonstration Guidance(56 pp, 673 K, 05-30-2019, 454-R-19-004)

Technical Guidance for Demonstration of Inter-Precursor Trading (IPT) for Ozone in the Nonattainment New Source Review Program (PDF)(38 pp, 11 MB, 05-01-2018, 454-R-18-004)

Draft Criteria For Assessing Whether an Ozone Nonattainment Area is Affected by Overwhelming Transport (PDF)(8 pp, 30 K, 06-29-2005) and the Errata Sheet for Draft Criteria: March 28, 2006 (PDF)(1 pg, 10 K, 03-28-2006)

Frequently Asked Questions on Implementing the DRAFT 8-Hour Ozone Modeling Guidance to Support Attainment Demonstrations for Early Action Compact (EAC) (PDF)(9 pp, 30 K, 02-23-2004)

Guidance for the 1-hour Ozone Nonattainment Areas that Rely on Weight-of-Evidence for Attainment Demonstrations (PDF)(31 pp, 67 K, 03-28-2002) - Mid-Course Review Guidance

Guidance for Improving Weight-of-Evidence Through Identification of Additional Emission Reduction Not Modeled (PDF)(10 pp, 192 K, 11-01-1999)

Guidance on Use of Modeled Results to Demonstrate Attainment of 1-hr Ozone NAAQS (ZIP)(153 K, 07-29-1996)

Guideline for Regulatory Application of the Urban Airshed Model (PDF)(83 pp, 130 K, 07-01-1991)

Note: Information on air quality modeling of individual sources for visibility assessments can be found at:

Phase I Guidance:

National Park Service (1993): Interagency Workgroup on Air Quality Modeling (IWAQM) Phase 1 Report: Interim Recommendation For Modeling Long Range Transport And Impacts On Regional Visibility (PDF)(105 pp, 2 MB, 04-01-1993, 454-R-93-015). U.S. Environmental Protection Agency, Technical Support Division, Research Triangle Park, North Carolina 27711.

U.S. Environmental Protection Agency (1995): Interagency Workgroup on Air Quality Modeling (IWAQM): Assessment of Phase 1 Recommendations Regarding the Use of MESOPUFF II (PDF)(137 pp, 601 K, 12-01-1995, 454-R-95-006). Office of Air Quality Planning and Standards, U.S Environmental Protection Agency, Research Triangle Park, NC 27711.

Phase II Guidance:

Irwin, J.S., (1998): Interagency Workgroup on Air Quality Modeling (IWAQM) Phase 2 Summary Report and Recommendations for Modeling Long Range Transport Impacts (PDF)(160 pp, 3 MB, 12-01-1998, 454-R-98-019). Office of Air Quality Planning and Standards, Research Triangle Park, NC, 151 pp. (NTIS Accession Number PB 99-121089).

Garrison, M., A. Gray, S.T. Rao, M. Scruggs (1999): Peer Review of the Interagency Workgroup On Air Quality Modeling Phase 2 Summary Report And Recommendations For Modeling Long Range Transport Impacts (PDF)(67 pp, 184 K, 01-01-1999). This Report was Compiled by: John S. Irwin Air Policy Support Branch, Atmospheric Sciences Modeling Division U.S. Environmental Protection Agency Research Triangle Park, NC 27711, 64 pp.

U.S Environmental Protection Agency (1999): Response To Peer Review Comments of the Interagency Workgroup On Air Quality Modeling Phase 2 Summary Report And Recommendations For Modeling Long Range Transport Impacts (PDF)(4 pp, 13 K, 02-01-1999).

U.S. Environmental Protection Agency (2009): Draft Reassessment of the Interagency Workgroup on Air Quality Modeling (IWAQM) Phase 2 Summary Report: Revisions to Phase 2 Recommendations (PDF)(56 pp, 1 MB, 05-27-2009).

U.S. Environmental Protection Agency (2012): Documentation of the Evaluation of CALPUFF and Other Long Range Transport Models using Tracer Field Experiment Data (PDF)(247 pp, 8 MB, 05-01-2012, 454-R-12-003). EPA Contract No: EP-D-07-102, Work Assignment No: 4-06.

PM10 Guidance
Fugitive Dust Guidelines (ZIP)(692 K, 12-09-1996) - Guidance for modeling fugitive dust: Phase I, II & III, December 9, 1996

Carbon Monoxide Guidance
Guideline for Modeling Carbon Monoxide from Roadway Intersections (PDF)(64 pp, 546 K, 11-01-1992, 454-R-92-005) - Applicable for roadway intersections

US EPA

Support Center for Regulatory Atmospheric Modeling (SCRAM)

State Implementation Plan (SIP) Attainment Demonstration Guidance

Air Quality Models