Tire and brake wear identified as major sources of road pollution

Tire and brake wear have emerged as significant sources of non-exhaust particulate pollution. In the United States, these particles account for nearly 60% of road transport particulate pollution, a figure that has risen as tailpipe emissions have decreased due to advanced engineering.

Globally, approximately 6 million tons of tire wear particles are released annually. This contributes to 5–10% of ocean microplastics and 3–7% of airborne particulate matter. Research indicates that tire particle emissions can be up to 1,850 times higher than vehicle exhaust per kilometer driven. Specifically, tires shed about 36 milligrams of particles per kilometer, whereas a modern gasoline particulate filter can reduce tailpipe emissions to as little as 0.02 milligrams.

The environmental and health impacts are substantial. Particles smaller than 23 nanometers can enter the bloodstream and reach internal organs. Additionally, substances such as 6PPD-quinone, found in tire debris, have been identified as highly toxic to aquatic systems. Brake wear further adds to this load, with emissions ranging from 3.3 to 13.6 milligrams per mile depending on vehicle type and driving conditions.