The California Air Resources Board (CARB) has taken significant steps to address emissions from heavy-duty vehicles, which contribute disproportionately to air pollution on the state's roads. The Clean Truck Check program, also known as Heavy Duty Inspection and Maintenance (HD I/M), aims to monitor and reduce emissions from these vehicles.

HD I/M applies to heavy-duty, non-gasoline vehicles with a gross vehicle weight rating (GVWR) over 14,000 pounds. This includes buses, trucks, agricultural equipment, and motorhomes. Despite comprising only 3% of vehicles on California's roads, heavy-duty vehicles are responsible for over half of the smog-causing pollution and fine particulate matter from mobile sources.

The Clean Truck Check program requires heavy-duty vehicle owners to test their emissions regularly and submit the results to CARB. This is designed to improve the identification and repair of malfunctioning emissions systems, which can occur even in modern vehicles with aftertreatment systems.

 One innovative aspect of the Clean Truck Check program is its use of onboard diagnostics (OBD) systems. OBD systems allow CARB-authorized testers with certified readout devices to collect emissions data from anywhere, rather than requiring vehicles to travel to a testing facility. This is expected to simplify implementation, as CARB anticipates that 75%-80% of heavy-duty trucks will have OBD systems when the program begins.

 The Clean Truck Check program is expected to have significant benefits for air quality and public health in California. CARB estimates that the program will prevent 7,500 deaths related to air quality between 2023 and 2050 and generate $75 billion in health benefits. This is over 18 times the estimated $4 billion cost of the program.

 Overall, the Clean Truck Check program represents a comprehensive and forward-thinking approach to reducing emissions from heavy-duty vehicles in California. By leveraging technology and focusing on regular testing and maintenance, CARB aims to improve air quality and protect public health in the state.