Rules of the Road: Examining Legislation to Modernize the Clean Air Act's Mobile Source Requirements

The House Committee on Energy and Commerce held a subcommittee hearing on May 27, 2026, titled "Rules of the Road: Examining Legislation to Modernize the Clean Air Act's Mobile Source Requirements." The hearing focused on reviewing ten legislative proposals aimed at updating Title II of the Clean Air Act, which governs emissions from mobile sources such as vehicles, locomotives, and heavy-duty diesel engines. Key procurement-related discussions included the economic and operational impacts of California's emission waiver authority on national standards, the costs and benefits of diesel emission reduction technologies like selective catalytic reduction (SCR) and diesel exhaust fluid (DEF), and the reauthorization of the Diesel Emission Reduction Act (DERA) which funds grants and loans to retrofit or replace older diesel engines. Witnesses from industry associations and environmental groups provided testimony on the balance between environmental protection, regulatory certainty, and economic impacts on manufacturers, operators, and consumers. Several members expressed concerns about the cost burdens imposed by state-level mandates, particularly California's, and the need for a uniform national standard to avoid patchwork regulations that increase costs and complicate interstate commerce. The hearing also addressed the potential effects of proposed bills on idling restrictions for buses and the implications for public health and operational safety. No specific contract awards or procurement actions were taken during the hearing, but the discussions highlighted policy considerations that could influence future procurement and regulatory activities related to clean transportation technologies and infrastructure.