California Air Resources Board

SACRAMENTO – The California Air Resources Board today approved a ‘smog check’ regulation for medium- and heavy-duty trucks and buses. While these heavy-duty vehicles with a gross vehicle weight rating (GVWR) greater than 14,000 pounds comprise only 3 percent of all vehicles on California roads, they are responsible for more than 50 percent of nitrogen oxides and fine particle diesel pollution from all mobile sources in the state.

The action taken by CARB today will cover roughly 1 million heavy-duty trucks and buses operating in California. The twice-a-year inspections will ensure that the emissions control systems maintain the same efficiency as the vehicle ages. By 2037, the program is estimated to deliver reductions of 82 tons per day of NO_x and fine particle diesel pollution. The Board also directed a four-times per year testing frequency for trucks with on-board diagnostics to be phased in over time.

“This first-in-the-nation program will prevent trucks and buses from emitting unhealthy pollutants from their engines for the life of the vehicle,” said CARB Chair Liane Randolph. “This commonsense measure will provide the pollution reductions we urgently need to achieve federal air quality standards and deliver cleaner air to impacted communities near ports, freeways, and warehouses."

The new program is expected to yield $75 billion in health benefits, prevent 7,500 air-quality related deaths and 6,000 hospitalizations and emergency room visits from 2023 to 2050. These benefits are 18 times the estimated cost of the program at $4 billion.

The program is designed to provide a convenient approach for compliance to businesses and vehicle owners, prevent highly polluting trucks and buses from being registered, and will result in the rapid repair of malfunctioning emissions control equipment when it breaks.

The new program implements SB 210, authored by Senator and ex-officio Board member Connie Leyva in 2019, directing CARB to develop and implement a new, comprehensive Heavy-Duty Inspection and Maintenance program to control emissions more effectively from non-gasoline on-road heavy-duty vehicles. It will also include independent owner/operators who were exempt from the current program of periodic smoke inspections.

“I am beyond excited that this historic program will finally be implemented across California and that it will result in the largest reduction in NOx emissions since the Truck and Bus Regulations were adopted in 2008. Just as passenger vehicles have already been doing for decades, it is long overdue that big diesel trucks undergo smog check testing so that we can continue to clean our air and improve public health across California. By keeping polluting dirty trucks off our freeways and roads, we will take an important step forward in further cleaning the air across our state,” Senator Leyva said. “The benefits this program will bring to our environment, our communities and the health and wellbeing of our families is a clear win-win for all Californians.”

The Heavy-Duty Inspection and Maintenance program will roll out a statewide network of roadside emission monitors to screen for high emitting trucks, starting with the San Joaquin Valley and South Coast and expanding over time. It will also require vehicles with a GVWR greater than 14,000 pounds operating in California to perform periodic testing and submit the data to CARB. As with passenger cars and light-duty trucks, California registration of these heavier vehicles will require passing the inspection. Unlike light-duty smog checks, however, there is no requirement to go to a ‘brick and mortar’ heavy-duty smog check station.

Heavy-duty vehicle owners will be able to complete the required test and deliver the information remotely without having to travel to designated testing locations. For telematics users, an onboard diagnostics (OBD) inspection that draws emissions control performance data from the vehicle’s internal computer, an inspection can be completed automatically without taking the vehicle out of operation. OBD systems have been required by CARB on heavy-duty vehicles since 2013. Older heavy-duty vehicles without on-board diagnostic systems would continue the current opacity testing requirements with an added visual testing component, twice each year.

The Heavy-Duty Vehicle Inspection Program will continue to augment the new testing requirements with inspections and testing randomly carried out at border crossings, California Highway Patrol weigh stations, fleet facilities and randomly selected roadside locations.

More Information