Proposed rule · 2025-13341

Air Quality State Implementation Plans; Approval and Promulgations: Montana: Infrastructure Requirements for the 2015 Ozone National Ambient Air Quality Standards

The Environmental Protection Agency (EPA) is proposing to approve elements of a state implementation plan (SIP) submission from Montana regarding the infrastructure requirements of the Clean Air Act (CAA) for the 2015 ozone National Ambient Air Quality Standards (NAAQS). The infrastructure requirements are designed to ensure that the structural components of each state's air quality management program are adequate to meet the state's responsibilities under the CAA. Additionally, EPA is proposing to approve Montana's request to update their SIP, to incorporate the most current version of the "Guideline on Air Quality Models." The EPA is taking this action pursuant to the CAA.