Ignoring Federal EPA, the California Air Resources Board (CARB) staff has posted a draft potential Tier 5 Regulation Order, which will be discussed at a February 27, 2026, public workshop. Staff has made substantial updates to the previous draft of the potential Tier 5 Regulation Order, including changes to the potential Tier 5 standards for criteria pollutants and greenhouse gases, implementation timelines, the Off-Road In-Use Testing program, zero-emission credits, durability demonstrations, and potential requirements for hydrogen-fueled internal combustion engines.
CARB staff is considering cleaner exhaust emission standards for NOx (up to 90% cleaner than today’s Tier 4 standards) and PM (up to 75% cleaner than today’s Tier 4 standards). Other elements include enhanced in-use compliance testing, more representative useful life periods, OBD requirements (applicable for the first time to this category), and a new low-load test cycle. This workshop is the tenth public event in CARB’s development of potential Tier 5 regulations. CARB staff invites industry, fleet owners, trade associations, representatives of non-governmental organizations, environmental groups, air districts, members of the community, and other interested stakeholders to participate and provide feedback on the draft Regulation Order and draft Test Procedures for the Tier 5 rulemaking. The Association continues to oppose further regulations and restrictions, as California farmers already face the toughest air quality regulations in the country, if not the world.