The Governing Board has approved two new research
contracts to better understand air pollution from vehicle
brake and tire wear, pollution sources that are becoming
more significant as tailpipe emissions continue to decline.
Non-exhaust emissions, including particles from brakes and
tires, are anticipated to become a leading source of direct
particulate matter (PM) from vehicles. While electric vehicles
can reduce brake-wear pollution through regenerative braking,
their heavier weight may increase tire-wear emissions.
The studies will be conducted by the University of California,
Riverside Center for Environmental Research and
Technology (UCR/CE-CERT) and funded through the
Clean Fuels Program Fund.
The first study, funded at up to $200,000, will examine
gases released from tires as they age and heat up.
These gases can react in the atmosphere to form
secondary organic aerosol, a type of fine particle.
Laboratory testing has shown emissions increase
significantly with temperature and vary by tire brand,
age, and air chemistry. Most secondary particle
formation occurs within days.
The second study, funded at up to $600,000, will
measure real-world brake and tire-wear emissions
from light-, medium-, and heavy-duty vehicles, expanding
earlier work led by the CARB. Researchers will test a range of
vehicle types, including battery-electric and goods movement
trucks.
Tire wear is also a major source of microplastics and can
contain heavy metals and other potentially toxic compounds
linked to respiratory and cardiovascular health concerns.
Together, the projects will help quantify these growing pollution
sources and inform future strategies to reduce exposure and
improve air quality across the South Coast Air Basin.