Air Plan Approval; New Hampshire; Repeal of Motor Vehicle Inspection and Maintenance Program

The U.S. Environmental Protection Agency (EPA) is proposing to conditionally approve a State Implementation Plan (SIP) revision submitted by the State of New Hampshire on December 24, 2025, through the New Hampshire Department of Environmental Services (NHDES). The proposed revision would remove the Statewide motor vehicle inspection and maintenance (I/M) program as an active measure, which was previously approved into the SIP to address emissions from on-road sources. In accordance with plan revision requirements of the Clean Air Act (CAA), the SIP submittal contains a demonstration that the removal of the I/M program will not interfere with New Hampshire's compliance with any National Ambient Air Quality Standard (NAAQS) or with any applicable requirement of the CAA. In a letter to the EPA, NHDES committed to submitting an additional SIP revision within one year of a final conditional approval to address maintenance plan requirements.