Particulate emissions from motorcycle brakes: non-combustion sources of urban pollution

Interest in the emission of non-combustion particulate matter has quickly grown. Although its negative impact on people’s health is well documented, information regarding the emission source, its constituents and the particle size distribution, and its impact is much more scarce. For example, the impact of braking system materials in particulate matter emission is not fully understood. When looking at motorcycle data, the lack of information is even more noticeable. Considering that in some regions the motorcycle fleet is the most prominent one, understanding their particulate matter emission better is essential. The main goal of the present work is to analyse the particulate emissions of a motorcycle braking system. A testing rig was developed using a motorcycle where the acceleration and braking processes were automated. Comparison between braking pads manufactured using different materials was performed and the particle size distribution was analysed. The applied methodology and test set-up was able to characterise the particle size distribution across a wide diameter range (from sub-micrometre dimensions up to 20 micrometres). It was observed that metallic pads generated a lower quantity of small particulate matter (under one micron), while ceramic pads presented a tendency to emit more particles within this size range.