# Revision to the Guideline on Air Quality Models: Adoption of a Preferred Long Range Transport Model and Other Revisions
> **Rule** · Final rule. · Published 2003-04-15 · Effective 2003-05-15 · 68 FR 18440
## Document
- **Document number:** 03-8542
- **Category:** air-emissions
- **Federal Register citation:** 68 FR 18440
- **CFR reference:** 40 CFR 51
- **Publication date:** 2003-04-15
- **Effective date:** 2003-05-15
- **EPA docket:** AH-FRL-7478-3
## Abstract

EPA's Guideline on Air Quality Models ("Guideline") addresses the regulatory application of air quality models for assessing criteria pollutants under the Clean Air Act. In today's action we promulgate several additions and changes to the Guideline. We adopt a new dispersion model, CALPUFF, in appendix A of the Guideline. CALPUFF becomes the preferred technique for assessing long range transport of pollutants and their impacts on Federal Class I areas. Action on AERMOD and the Emissions and Dispersion Modeling System (EDMS) is deferred. We make various editorial changes to update and reorganize information, and remove obsolete models.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2003/04/15/03-8542/revision-to-the-guideline-on-air-quality-models-adoption-of-a-preferred-long-range-transport-model)
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