Tire Chemicals and Particles

Vehicle Tires Threaten Wildlife

When it rains, stormwater runoff washes micro- and nano-sized tire particles, and the toxic chemicals they carry, from outdoor surfaces to aquatic ecosystems all around the world. Our monitoring and research in this emerging and critically important field has already informed state regulation to protect salmon.

A World Leader on Tire Pollution

Our foundational 2019 study on microplastics in San Francisco Bay was the first in the world to identify tire wear particles in urban stormwater runoff. Our investigations suggest tires may be the biggest global source of microplastics to the environment.

Using innovative nontarget analysis techniques, we identified toxic tire-derived chemicals contaminating stormwater in local streams and San Francisco Bay. Our research on tire particles and chemicals uses state of the art analytical methods and fills critical data gaps to inform pollution prevention efforts at local, state, and federal levels.

Fact Sheet: Essential Information on Tires and Water Quality

Each year, stormwater washes trillions of tiny particles shed by tires into San Francisco Bay. This fact sheet summarizes the impacts of tires on wildlife, and practical solutions to reduce pollution.

Photograph: Lonny Meyer/Courtesy of Estuary News

Toxic Tire-derived Contaminant in Bay Area Streams

In 2020, we discovered Bay Area stormwater contained a highly toxic tire contaminant, 6PPDQ, at levels lethal to coho salmon. Additional SFEI monitoring revealed 6PPDQ and other tire chemicals in creeks and the Bay. California agencies are using SFEI findings to tackle tire toxicity.

Tire Emissions Estimates to Inform Monitoring Design

We used tire market insights and two independent methods to estimate annual emissions of tire material of 2–3 kg per capita each year, roughly equal to a 5 lb sack of flour.

Photo: Mark Eliot

Joel Danielson

Sources and Solutions for Tire Particle Pollution

In 2021, SFEI published a report on tire wear particles that identified a broad spectrum of prevention and treatment options to address tire pollution. Our findings were incorporated into the Statewide Microplastics Strategy.