What is it about?

We explored the properties of particles produced from automotive disk brakes in a laboratory setting and found that the particles can be highly charged. As many as 80% of particles emitted from some brakes have at least some charge.

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Why is it important?

Brake wear particles is an important source of air pollution that will grow in significance as we transition to alternative fuels. Research has shown that these particles are harmful to human health and the environment. The observation that these particles are charged provides insights into their fate in the atmosphere as well as a possible means for removing these particles before they are emitted.


This study is part of a larger effort at the University of California, Irvine, to characterize non-exhaust emissions. Despite the fact that most people know that rubbing two surfaces together can create static charge, I was surprised to learn that no one has studied this phenomenon in automotive braking. We also observed stark differences in the properties of particles produced from different brake pad formulations, which emphasizes the role that brake pad composition may play on emissions.

James Smith
University of California Irvine

Read the Original

This page is a summary of: Automotive braking is a source of highly charged aerosol particles, Proceedings of the National Academy of Sciences, March 2024, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2313897121.
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