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On November 20, 2019, CARB released off-model adjustment factors to be used in conjunction with its EMFAC (short for EMission FACtor) 2014 and 2017 models. These adjustments were created by CARB to account for changes in vehicle emission calculations resulting from the federal issuance of the “Safer Affordable Fuel-Efficient (SAFE) Vehicles Rule Part One: One National Program” (SAFE Part One). SAFE Part One was issued by the U.S. Environmental Protection Agency (EPA) and the National Highway Traffic Safety Administration (NHTSA), and it revoked California's authority to set its own greenhouse gas (GHG) emissions standards and zero-emission vehicle (ZEV) mandates within the state.

Furthermore, in April 2020, the U.S. EPA and NHTSA issued the “SAFE Vehicles Rule for Model Years 2021-2026 Passenger Cars and Light Trucks” (Final SAFE Rule), which relaxed federal GHG emissions and fuel economy standards. CARB's evaluation of the Final SAFE Rule determined that its November 2019 EMFAC off-model adjustment factors remain valid and sufficient in accounting for the impacts of both SAFE Part One as well as the Final SAFE Rule in transportation conformity analyses.

However, CARB's November 2019 EMFAC off-model adjustment factors were only for criteria pollutants. On June 26, 2020, CARB announced its release of additional EMFAC off-model adjustment factors for Carbon Dioxide (CO2) to account for the SAFE Part One and the Final Safe Rules in both its EMFAC2014 and EMFAC2017 models.

For more information on the November 2019 release of CARB's EMFAC off-model adjustment factors for criteria pollutants, please see our article posted January 24, 2020.

For more information on CARB's EMFAC model and to access the off-model adjustment factors, please visit the CARB webpage.

Process to apply EMFAC Off-Model Adjustment Factors

Source: CARB 2019