California Air Resources Board

• EPA Approval Letter - 5/6/2026
• Attachment B – Guidance for CTC In-State EMFAC Off-Model Adjustments
• Appendix B – CTC In-State Factors

• Guidance For Applying EMFAC2021 Off-Model Adjustment Factors for PL Assessment
• EMFAC2021 Factors for PL Guidance

EMFAC2021 Off-Model Adjustment Factors to Remove the Impact of Advanced Clean Trucks, Zero-Emission Airport Shuttle, Heavy-Duty Omnibus and Warranty Phase I Regulations

• EPA Off-Model Adjustment Factors Approval Letter - 11/21/2025
• Attachment A – Description of EMFAC2021 Adjustment Factors
• Appendix A – EMFAC2021 Adjustment Factors

EMFAC2021 Off-Model Greenhouse Gas Adjustment Factors to Remove the Impact of Advanced Clean Trucks, Zero-Emission Airport Shuttle, Heavy-Duty Omnibus and Warranty Phase I Regulations

• EMFAC2021 GHG Adjustment Factors

• EMFAC2021 approval notice in the Federal Register - 11/15/2022
• EMFAC2021 (v1.0.2) Public Release Notice - 5/2/22
• EMFAC2021 (v1.0.1) to (v1.0.2) Updates - 5/2/22
• EMFAC2021 Software Installation Package (v1.0.2) - 5/2/22
• EMFAC2021 (v1.0.1) Public Release Notice - 4/30/21
• EMFAC2021 Software Installation Package (v1.0.1) - 4/28/21
• EMFAC2021 (v1.0.0) to (v1.0.1) Updates - 4/28/21
• EMFAC2021 PL Handbook - 3/26/21
• EMFAC2021 Technical Document - 4/28/21
• PHEV Start Analysis Draft Memo - 3/26/21
• EMFAC2021 (v1.0.0) Public Release Notice - 1/15/21
• EMFAC2021 User’s Guide