EPA Approves Montana's Updates to 2015 Ozone Air Quality Standards
Published Date: 11/18/2025
Rule
Summary
The EPA is giving Montana a thumbs-up for updating its air quality plan to meet the 2015 ozone pollution rules. This means Montana’s air programs are ready to keep the air cleaner and healthier. The new rule kicks in on December 18, 2025, with no extra costs for residents or businesses.
Analyzed Economic Effects
3 provisions identified: 3 benefits, 0 costs, 0 mixed.
Montana SIP Approved for 2015 Ozone
If you live in Montana, EPA approved the State Implementation Plan (SIP) elements that show Montana can meet the 2015 8-hour ozone air quality standards. This approval (including EPA acceptance of Montana's October 1, 2018 certification and related elements) is effective December 18, 2025.
No New Federal Costs for Montanans
EPA says this approval does not impose any additional requirements beyond Montana law and the rule will not add costs for residents or businesses. EPA certified the action as not having a significant economic impact on a substantial number of small entities and states it does not impose new information-collection burdens.
Does Not Apply on Indian Reservations
EPA's approval does not apply on any Indian reservation land or in any other area where an Indian Tribe has demonstrated jurisdiction. In those Tribal areas, the rule will not impose substantial direct costs on Tribal governments or preempt Tribal law.
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