Automotive brake wear: a review

Road transport systems generate toxic particulate matter (PM) when in motion, that ultimately finds its way to the atmosphere. The PM produced by road transport systems can be broadly classified as exhaust and non-exhaust emissions. Exhaust emission is primarily due to product of combustion, as is the case of internal combustion engines and the PM is released to the atmosphere through the tail. Non-exhaust PM sources can be classified as sources such as emissions due to brake wear, tyre wear, road surface wear and resuspension. Both exhaust and non-exhaust sources generate PM of various sizes and shapes that has an impact on our health. Strict legislations by authorities have led to reduced exhaust emissions; however, due to the nature of complexity of PM generation by non-exhaust sources, effective control of non-exhaust emission still needs to be developed. Thus, as exhaust emissions are being controlled, non-exhaust is becoming a significant source of PM emission. The present paper reviews work done by previous researchers on non-exhaust PM and specifically, brake wear from road transport systems as this is one of the most important non-exhaust source of PM in the environment. The finding of the paper would be beneficial to policy makers and researchers.