A field study of airborne particle emissions from automotive disc brakes

Abstract

Airborne particle emissions from automotive disc brakes, one of the main sources of urban particulate matter, adversely affect health. Field measurement of brake particles is complicated, as various particle sources (such as tailpipe emissions, resuspended road dust and tyre wear) can interfere. Brake particles are usually measured on dyno benches or in model-scale tests in controlled environments. Such test results need confirmation in the field, where air flow around disc brakes differs completely. Few field studies focusing on disc brake particles have been reported in the literature. The objective of this work is to investigate further the possibility of measuring brake particles in the field using particle instruments mounted on a car. A car was instrumented with two GRIMM 1.109 aerosol spectrometers and two TSI DustTrak 8520 aerosol monitors. One GRIMM spectrometer and one TSI DustTrak monitor recorded data near the brake, and the other GRIMM spectrometer and the other TSI DustTrak monitor recorded data at the front of the car during five field tests in outer Stockholm. The results suggest that braking directly correlates with increased particle concentrations measured near the brake. The reported test stand results correlate with the field-measured number distributions.