Skip to Content


Conference on Air Quality Modeling

Document Details

Information about this document as published in the Federal Register.

Published Document

This document has been published in the Federal Register. Use the PDF linked in the document sidebar for the official electronic format.

Start Preamble


Environmental Protection Agency (EPA).


Notice of conference.


We announce the Ninth Conference on Air Quality Modeling. Such a conference is required by Section 320 of the Clean Air Act (CAA) to be held every 3 years. The purposes of the ninth conference are to provide an overview of the latest features of the new air quality models and to provide a forum for public review and comment on potential revisions to the way the Agency determines and applies the appropriate air quality models in the future.


Comments: Comments on potential revisions to the way the Agency determines and applies the appropriate air quality models must be received on or before November 10, 2008.

Conference: The conference will be held on October 9, 2008 from 8:30 a.m. to 5:30 p.m. and on October 10, 2008 from 8:30 a.m. to 5 p.m. Requests to speak at the conference should be submitted to the individual listed below by October 3, 2008.


Comments: Submit your comments, identified by Docket ID No. EPA-HQ-OAR-2008-0604 by one of the following methods:

  • Follow the on-line instructions for submitting comments. This is EPA's preferred method for receiving comments.
  • E-mail: Comments may be sent by electronic mail (e-mail) to, Attention Docket ID No. EPA-HQ-OAR-2008-0604.
  • Fax: Fax your comments to 202-566-9744, Attention Docket ID No. EPA-HQ-OAR-2008-0604.
  • Mail: Send your comments to: Air and Radiation Docket and Information Center, Environmental Protection Agency, Mailcode: 2822T, 1200 Pennsylvania Ave., NW., Washington, DC 20460, Attention Docket ID No. EPA-HQ-OAR-2008-0604.
  • Hand Delivery or Courier: Deliver your comments to EPA Docket Center, 1301 Constitution Ave., NW., Room 3334, Washington, DC. Such deliveries are only accepted during the Docket's normal hours of operation, and special arrangements should be made for deliveries of boxed information.

Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-2008-0604. EPA's policy is that all comments received will be included in the public docket without change and may be made available online at, including any personal information provided, unless the comment includes information claimed to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Do not submit information that you consider to be CBI or otherwise protected through or e-mail. The Web site is an “anonymous access” system, which means EPA will not know your identity or contact information unless you provide it in the body of your comment. If you send an e-mail comment directly to EPA without going through, your e-mail address will be automatically captured and included as part of the comment that is placed in the public docket and made available on the Internet. If you submit an electronic comment, EPA recommends that you include your name and other contact information in the body of your comment and with any disk or CD-ROM you submit. If EPA cannot read your comment due to technical difficulties and cannot contact you for clarification, EPA may not be able to consider your comment. Electronic files should avoid the use of special characters, any form of encryption, and be free of any defects or viruses. For additional information about EPA's public docket visit the EPA Docket Center homepage at​epahome/​dockets.htm.

Docket: All documents in the docket are listed in the index. Although listed in the index, some information is not publicly available, e.g., CBI or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, will be publicly available only in hard copy form. Publicly available docket materials are available either electronically in or in hard copy at the Air Docket in the EPA Docket Center, EPA West, Room 3334, 1301 Constitution Ave., NW., Washington, DC. This Docket Facility is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The Docket telephone number is (202) 566-1742; fax (202) 566-9744.

Background Information: Additional information and a more detailed agenda are electronically available at​ttn/​scram/​9thmodconf.htm.

Conference: The conference will be held in the EPA Auditorium, Room C111, 109 T.W. Alexander Drive, Research Triangle Park, NC.

Start Further Info


Peter Eckhoff, U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards, Air Quality Assessment Division, Mail Code C439-01, Research Triangle Park, NC 27711; telephone: (919) 541-5385; fax: (919) 541-0044; e-mail address:

End Further Info End Preamble Start Supplemental Information


I. General Information

A. What Should I Consider as I Prepare My Comments for EPA?

1. Submitting CBI. Do not submit this information to EPA through or e-mail. Clearly mark the part or all of the information that you claim to be CBI. For CBI information in a disk or CD ROM that you mail to EPA, mark the outside of the disk or CD ROM as CBI and then identify electronically within the disk or CD ROM the specific information that is claimed as CBI. In addition to one complete version of the comment that includes information claimed as CBI, a Start Printed Page 55509copy of the comment that does not contain the information claimed as CBI must be submitted for inclusion in the public docket. Information so marked will not be disclosed except in accordance with procedures set forth in 40 CFR part 2.

2. Tips for Preparing Your Comments. When submitting comments, remember to:

  • Identify the rulemaking by docket number and other identifying information (subject heading, Federal Register date and page number).
  • Follow directions—The agency may ask you to respond to specific questions or organize comments by referencing a Code of Federal Regulations (CFR) part or section number.
  • Explain why you agree or disagree; suggest alternatives and substitute language for your requested changes.
  • Describe any assumptions and provide any technical information and/or data that you used.
  • If you estimate potential costs or burdens, explain how you arrived at your estimate in sufficient detail to allow for it to be reproduced.
  • Provide specific examples to illustrate your concerns, and suggest alternatives.
  • Explain your views as clearly as possible, avoiding the use of profanity or personal threats.
  • Make sure to submit your comments by the comment period deadline identified.

II. Background

The Guideline on Air Quality Models (hereafter, called the Guideline, which is found in Appendix W to 40 CFR Part 51), is used by EPA, States, and industry to prepare and review new source permits and State Implementation Plan revisions. The Guideline serves as a means by which consistency is maintained in air quality analyses. We originally published the Guideline in April 1978 and it was incorporated by reference in the regulations for the Prevention of Significant Deterioration (PSD) of Air Quality in June 1978. We revised the Guideline in 1986, and updated it with supplement A in 1987, supplement B in July 1993, and supplement C in August 1995. We published the Guideline as appendix W to 40 CFR part 51 when we issued supplement B. We republished the Guideline in August 1996 (61 FR 41838) to adopt the CFR system for labeling paragraphs.

To support the process of developing and revising the Guideline during the period 1977-1988, we held the First, Second and Third Conferences on Air Quality Modeling as required by Section 320 of the Clean Air Act to help standardize modeling procedures. These modeling conferences provided us with comments on the Guideline and associated revisions, thereby helping us introduce improved modeling techniques into the regulatory process.

In October 1988, we held the Fourth Conference on Air Quality Modeling. Its purpose was to advise the public on new modeling techniques and to solicit comments to guide our consideration of any rulemaking needed to further revise the Guideline. We held the Fifth Conference on Air Quality Modeling in March 1991, which served as a public hearing for the proposed revisions to the Guideline. In August 1995, we held the sixth conference as a forum to update our available modeling tools with state-of-the-science techniques for airing these issues and for the public to offer new ideas. The Seventh Conference was held in June 2000 and served as a public hearing for the proposed changes to the recommended air quality models in Appendix W including the CALPUFF modeling system and AERMOD.[1]

The last conference held was the Eighth Conference on Air Quality Modeling in September 22 and 23, 2005, which provided details on recent and impending changes to the recommended air quality models in Appendix W. Several presentations were made, including regulatory status and details on the AERMOD modeling system, the EPA's preferred model for near-field regulatory applications; the regulatory status and implementation issues with the CALPUFF modeling system, the EPA's preferred model for long-range transport of criteria pollutants and their impacts on Federal Class I areas; and on EPA's approach to updating the approved versions of regulatory models under Appendix W to address coding bugs or implementation issues. In addition, several presentations were provided on the current and available methods for model performance evaluation and a panel of experts discussed the use of state-of-the-science prognostic meteorological data for our new dispersion models. The proceedings are found in Docket No. OAR-2005-0157.

III. Public Participation

The Ninth Conference on Air Quality Modeling will be open to the public; no admission fee is charged and there is no formal registration. The conference will begin the first morning with introductory remarks by the presiding EPA official. The following topics will be presented:

I. Overview of Appendix W

II. AERMOD Status and Updates

III. CALPUFF Status and Updates

IV. Non-Guideline Applications of Dispersion Models

V. Update on Use of Assimilated Meteorological Data for Dispersion Models

VI. Review of Current and Available Model Evaluation Methods

VII. Review of New and Emerging Models/Techniques for Future Consideration Under Appendix W; and

VII. Other Presentations by the Public

Those wishing to speak at the conference, whether to volunteer a presentation on a special topic or to offer general comment on any of the modeling techniques scheduled for presentation, should contact us at the address given in the FOR FURTHER INFORMATION CONTACT section (note the cutoff date). Such persons should identify the organization (if any) on whose behalf they are speaking and the length of the presentation. If a presentation of general comments is projected to be longer than 10 minutes, the presenter should also state why a longer period is needed. Persons failing to submit a written notice but desiring to speak at the conference should notify the presiding officer immediately before the conference, and they will be scheduled on a time-available basis.

The conference will be conducted informally and chaired by an EPA official. There will be no sworn testimony or cross examination. A verbatim transcript of the conference proceedings will be produced and placed in the docket. Speakers should bring extra copies of their presentation for inclusion in the docket and for the convenience of the recorder. Speakers will also be permitted to enter written comments into the record. Additional written statements or comments should be sent to the OAR Regulatory Docket (see ADDRESSES section). A transcript of the proceedings and a copy of all written comments will be maintained in Docket ID No. EPA-HQ-OAR-2008-0604 which will remain open until November 10, 2008 for the purpose of receiving additional comments.

Start Signature

Dated: September 18, 2008.

Jennifer Edmonds,

Acting Director, Office of Air Quality Planning and Standards.

End Signature End Supplemental Information


1.  A MS/E PA R egulatory MOD el; AERMOD was developed by AERMIC: A MS/E PA R egulatory M odel I mprovement C ommittee.

Back to Citation

[FR Doc. E8-22537 Filed 9-24-08; 8:45 am]