California Air Resources Board

Category specific emissions estimates have been developed over the past several years in support of specific agency regulatory objectives. The EMFAC emissions model is developed and used by CARB to assess emissions from on-road vehicles including cars, trucks, and buses in California, and to support CARB's regulatory and air quality planning efforts to meet the Federal Highway Administration's transportation planning requirements. US EPA approves EMFAC for use in State Implementation Plan and transportation conformity analyses. In the past CARB released the Off-Road model which calculated emissions from off-road sources. The Off-Road model is now being replaced by category specific methods and inventory models that are being developed for specific regulatory support projects. The categories listed below have been or are being updated with new methods and data. Where available, new inventories and models are provided.