G/TBT/N/USA/2065  
6 November 2023  
(23-7463) Page: 1/2 
Committee on Technical Barriers to Trade  Original:  English  
 
  
NOTIFICATION  
The following notification is being circulated in accordance with Article 10.6  
 
1. Notifying Member:  UNITED STATES OF AMERICA  
If applicable, name of local government involved (Article 3.2 and 7.2):   
2. Agency responsible:   
Environmental Protection Agency (EPA) [2096]  
Name and address (including telephone and fax numbers , email and website 
addresses, if available) of agency or authority designated to handle comments 
regarding the notification shall be indicated if different from above:   
Please submit comments to: USA WTO TBT Enquiry Point, Email: usatbtep@nist.gov  
3. Notified under Article 2.9.2 [  ], 2.10.1 [  ], 5.6.2 [  ], 5.7.1 [  ], 3.2 [  ], 7.2 [  ], 
other  [X]: The Guideline on Air Quality Models ("Guideline") serves as a means by which 
national consistency is maintained in air quality analyses for regulatory activities under 
Clean Air Act (CAA) regulations, including 40 CFR 51.112, 5 1.117, 51.150, 51.160, 
51.165, 51.166, 52.21, 93.116, 93.123, and 93.150.  
4. Products covered (HS or CCCN where applicable, otherwise national tariff 
heading. ICS numbers may be provided in addition, where applicable):  Air quality; 
Environmental protectio n (ICS code(s): 13.020); Air quality (ICS code(s): 13.040)  
5. Title, number of pages and language(s) of the notified document:  Guideline on Air 
Quality Models; Enhancements to the AERMOD Dispersion Modeling System; (43 page(s), 
in English)  
6. Description  of content:  Proposed rule; notification of public hearing and conference - 
In this action, the Environmental Protection Agency (EPA) proposes to revise the Guideline 
on Air Qua lity Models ("Guideline") . The Guideline has been incorporated into EPA's 
regulations, satisfying a requirement under the Clean Air Act (CAA)  section 165(e)(3)(D) 
for the EPA to specify, with reasonable particularity, models to be used in the Prevention 
of Significant Deteri oration (PSD)  program. It provides EPA -preferred models and other 
recommended techniques, as well as guidance for their use in predicting ambient 
concentrations of air pollutants. In this action, the EPA is proposing rev isions to the 
Guideline, including enhancements to the formulation and application of the EPA's near -
field dispersion modeling system, AERMOD , and updates to the recommendations for the 
development of appropriate background concentration for cumulative impact analyses. 
Within this action, the EPA is also announcing the Thirteenth Conference on Air Quality 
Modeling and i nvites the public to participate in the conference. The conference will focus 
on the proposed revisions to the Guideline, and part of the conference will also serve as 
the public hearing for these revisions.  
The public hearing for this action and the Thirt eenth Conference on Air Quality Modeling 
will be held 14 -15 November 2023, from 8:30 a.m. to 5:00 p.m. Eastern Standard Time 
(EST) . G/TBT/N/USA/2065  
 
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  7. Objective and rationale, including the nature of urgent problems where 
applicable:  Protection of the environment  
8. Relevant documents:   
88 Federal Register (FR) 72826, 23 October 2023; Title 40 Code of Federal Regulations 
(CFR) Part 51 :  
https://www.govinfo.gov/content/pkg/FR -2023-10-23/html/2023 -22876.htm  
https://www.govinfo.gov/content/pkg/FR -2023-10-23/pdf/2023 -22876.pdf  
This proposed rule; notification of publ ic hearing and conference is identified by Docket 
Number EPA -HQ-OAR-2022-0872. The Docket Folder is available on Regulations.gov at 
https://www.regulations.gov/docket/EPA -HQ-OAR-2022-0872/document  and provides 
access to primary and supporting documents as well as comments received. Documents 
are also accessible from Regulations.gov  by searching the Docket Number. WTO Members 
and their stakeholders are asked to submit comments to the USA TBT Enquiry Point . 
Comments received by the USA TBT Enquiry Point from WTO Members and their 
stakeholders by 4pm Eastern Time  on 22 December 2023 will be shared with EPA and will 
also be submitted to the Docket  on Regulations.gov if received within the comment 
period.  
9. Proposed date of adoption:  To be determined  
Proposed date of entry into force:  To be determined  
10. Final date for comments:  22 December 2023  
11. Texts available from:  National enquiry point [ ] or address, telephone and fax 
numbers and email and website addresses, if available , of other body:   
https://members.wto.org/crnattachments/2023/TBT/USA/23_13317_00_e.pdf