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Particulate air pollution from road traffic currently represents significant environmental and health issue. Attention is also paid to the “non-exhaust pollution sources,” which includes brake wear debris. During each brake application, the airborne and nonairborne particles are emitted into the environment due to wear. High temperatures and pressures on the friction surfaces initiate chemical and morphological changes of the initial components of brake pads and rotating counterparts. Understanding of impact of matter released from brakes on health is vital. Numerous studies clearly demonstrated that particulate matter caused potential adverse effects related to cytotoxicity, oxidative stress, stimulation of proinflammatory factors, and mutagenicity on the cellular level. This paper compiles our main results in the field of genotoxicity, immunotoxicity, and aquatic toxicity of airborne brake wear particles. The brake wear particles were generated using an automotive brake dynamometer.

Copper and copper alloys are widely used in friction materials such as brake pad formulations as one of key ingredients by providing good thermal conductivity and high temperature friction stability to achieve desired friction performance, fade and wear resistance. However, the use of copper or copper containing material is being restricted in brake pads due to environment and health concerns. Extensive works have been made to explore the copper substitutes but most of these efforts became ineffective and failed with issues either thermal fade or excessive pad/rotor wear. In this paper, friction and wear responses were examined when a metallic composite material was used as the copper substitute in NAO and Low-met brake formulations where the copper and copper alloys were added 8% and 22% respectively.

A number of brake lining materials representative of original equipment in US, Japanese and European automobiles were characterized in order to determine their composition and microstructure. Their frictional performance was subsequently determined using the Friction Assessment and Screening Test (FAST machine). The goal of this work was to identify each constituent of the friction material, to deduce their individual role in the friction process and to determine the effect of the microstructure on the wear properties.