Aqueous OH Radical Production by Brake Wear Particles (ACS EST Letters, 2024)
Authors: Ting Fang, Sukriti Kapur, Kasey C. Edwards, Hiroyuki Hagino, Lisa M. Wingen, Véronique Perraud, Adam E. Thomas, Bishop Bliss, David A. Herman, Andrea De Vizcaya Ruiz, Michael T. Kleinman, James N. Smith, Manabu Shiraiwa
Journal / Year: Environmental Science & Technology Letters, Vol. 11, Issue 4, 2024
Abstract:
This study examines how brake wear particles (BWPs) — a major non‑tailpipe emission source — generate hydroxyl radicals (·OH) in aqueous environments, which can increase oxidative stress associated with air pollution exposure. The authors found that BWPs from different brake pad materials (non‑asbestos organic, ceramic, and semimetallic) did not contain persistent free radicals but did generate significant levels of ·OH when suspended in water. Ceramic and semimetallic pads produced higher radical yields under heavier braking conditions. Results highlight the potential health impacts of traffic‑related particulate matter beyond traditional exhaust emissions, particularly as non‑exhaust sources grow with electrification of vehicles.