Mr. Carlos Agudelo, Link Engineering, UNITED STATES

Mr. Jeff Long, California Air Resources Board (CARB), UNITED STATES

Dr. Seungju Yoon, California Air Resources Board (CARB), UNITED STATES

Dr. Sam Pournazeri, California Air Resources Board (CARB), UNITED STATES

Dr. Jorn Herner, California Air Resources Board (CARB), UNITED STATES

Mr. Alan Stanard, Eastern Research Group (ERG), UNITED STATES

Mr. Sandeep Kishan, Eastern Research Group (ERG), UNITED STATES

Dr. Sonya Collier, California Air Resources Board, UNITED STATES

Dr. Ravi Vedula, Link Engineering. (LINK), UNITED STATES

Mr. Radoslaw Markiewicz, Link Engineering. (LINK), UNITED STATES

Dr. Simon Bisrat, California Department of Transportation (Caltrans), UNITED STATES

Mr. Jason Lee, California Department of Transportation (Caltrans), UNITED STATES

Mr. Chad Bailey, U.S. Environmental Protection Agency (U.S. EPA), UNITED STATES

Dr. Michael Aldridge, U.S. Environmental Protection Agency (U.S. EPA), UNITED STATES

Dr. Michael Hays, U.S. Environmental Protection Agency (U.S. EPA), UNITED STATES

Dr. Bob Giannelli, U.S. Environmental Protec

The mission of the California Air Resources Board (CARB) is to protect public health and mitigate the effects of climate change through regulatory and incentive programs. Regulatory measures at the vehicle tailpipe have led to substantial decreases in emissions, improvement in air quality and positive health outcomes.

Although regulations on tailpipe exhaust have resulted in significant decreases in particulate matter (PM) and other pollutants, non-exhaust sources, such as brake-wear PM, are modeled as dominant sources of vehicle PM by emission inventory models such as CARB’s EMFAC and US EPA’s MOVES models. However, both of these models primarily rely on old datasets and assumptions. As the non-exhaust emissions come to dominate total emissions, updates to emission factors and assumption are needed. They also do not take into account the likely decreases in brake-wear PM that will occur from fleet turnover and increased market share of vehicles equipped with regenerative braking.

To reduce uncertainties in current treatment of brake-wear PM emissions, CARB, in collaboration with Caltrans and U.S. EPA, is exploring various methods to quantify brake-wear PM emission rates. This includes controlled laboratory methods as well as roadside studies. Using recently developed testing methods, CARB is testing modern brake materials, under realistic braking behavior, testing various vehicle types and weights, and sampling with state-of-the-art PM measurement technologies. Laboratory methods will be used to develop new emission factors and source profiles, which can be used to estimate impacts of brake-wear in near-roadway environments. With this effort, CARB will improve EMFAC’s treatment of brake-wear PM and to characterize the exposure potential of populations living near major roadways to better understand the impact of this source on California’s air quality.