CARB Floats Options For ‘Tier 5’ Offroad Engine Rules But Doubts EPA Role

California air board officials are floating caps for several different greenhouse gases and hybrid engine options as part of their evolving first-time “Tier 5” emission standards for new off-road diesel engines, along with updated proposed “concepts” for providing compliance relief to small-volume manufacturers. But California Air Resources Board (CARB) staff said during an Aug. 8 workshop that EPA is not participating in their rule development process, and they don’t anticipate achieving agreement on a single, national set of Tier 5...