Projecting airborne tire wear particle emissions in the United States in the era of electric vehicles.

As electric vehicles (EVs) increasingly replace internal combustion engine vehicles (ICEVs) in the United States, non-exhaust particulate matter (PM) emissions-particularly tire wear particles (TWP)-are becoming a larger component of traffic-related air pollution. This study projects TWP emissions in the United States over the next 20 years (2024-2044), using the Motor Vehicle Emission Simulator (MOVES) model. The projections assume that the growth in the number of vehicles and vehicle electrification will follow the U.S. Department of Energy's Annual Energy Outlook (AEO). Furthermore, the study's projections are specifically adjusted to account for the increased weight of EVs. Our results indicate that while TWP emissions from ICEVs will decrease by 18 %, emissions from EVs could rise up to 17-fold, contributing nearly 40 % of total airborne PM from TWPs by 2044. Specifically, PM emissions from EVs are projected to rise from 0.1 kt in 2024 to nearly 2.0 kt in 2044, while PM emissions are expected to increase from 0.2 kt in 2024 to nearly 3.1 kt in 2044. These projections include a ±11 % uncertainty, reflecting variations in EV weight relative to ICEVs. The significant shift in emissions highlights the growing importance of TWPs in the era of vehicle electrification. Addressing this challenge will require advancements in tire design and EV battery technology to mitigate the added vehicle weight and associated TWP emissions.