Airborne brake wear particle emission due to braking and accelerating

The emission of airborne brake wear particles due to non-asbestos organic friction material was studied for two passenger cars and a middle class truck. The emission of airborne brake particulates was tested with a brake dynamometer with a constant volume sampling system and real-time mass measurements were made. The particles emissions under constant driving were calculated in terms of initial wheel speed and deceleration. Time series mass emissions were obtained by real-time dust monitors for PM2.5 and PM10. (i.e., particles with a 50% cutoff aerodynamic diameter of 2.5 and 10 mu m, respectively). The airborne brake wear particles emission occurred at deceleration and acceleration, suggesting resuspension of wear particles from friction on the surface of brakes and grooves at acceleration. The resuspended brake wear particles, whose emission during acceleration tended to increase with the initial speed, significantly contributed to the total emission. Therefore, they must be included in emission measurements of PM2.5 and PM10 during brake abrasion tests. Further measurements under a wide range of driving conditions, such as tailpipe emission test cycles, are required to obtain national and regional specific emission parameters for the development of inventories. (C) 2015 Elsevier B.V. All rights reserved.