Pollution from the brakes
As they wear out, brake pads release particles of dust in the ambient air, and those cause cardio-respiratory problems.
The frictional contact between the disc and the pads generates particles of various sizes. Apart from the mechanical abrasion, vehicle brakes become subject to large frictional heat generation with subsequent wear of linings and rotors.
This generates mostly micron-sized particles, approximately 50% of wear particles lie into diameters smaller than 20μm.
Modern brakes are composites of many different ingredients, chemical properties of the parent lining material are often modified due to high temperatures and pressures during the braking process.
Brake wear has been recognized as one of the most important non-exhaust traffic-related sources of air pollution.
It is estimated that approximately 50% of total brake wear is emitted as airborne, the rest may deposit on the road.
Brake wear contains particles from all fractions involved in the respiratory problems.
Additionally, some constituents of airborne brake wear particles have been recognized as dangerous for human health.
There are an estimated 260 million registered passenger vehicles in the United States and over 33 million registered in Canada. Brake dust from all those vehicles contributes to the billions that we spend each year on pollution-related healthcare. Roughly 150 million brake pads have to be replaced every year.
- U.S. National Library of Medicine, National Institutes of Health.
- Environmental Protection Agency
- Statistics Canada.