Study of brake wear particle emissions of a minivan on a chassis dynamometer

Car brakes appears to be a significant atmospheric pollutant source, with a contribution to total non-exhaust traffic related PM10 emissions being estimated at approximately 55% in big cities and urban environments (Bukowiecki et al., 2009). Brake wear particle emissions of a minivan running on a chassis dynamometer were measured using a custom sampling system, positioned close to the braking system, under different initial speeds (30km/h and 50km/h), deceleration rates (0.5m/s2 , 1.5m/s2, 2.5m/s2) and ambient temperature (0°C, 15°C and 25°C). Braking from 50km/h to full stop, results in 40-100% more particles compared to 30km/h, depending on the deceleration rate. It was also found that only 9-50% of the total particles emitted, are released during the braking phase and therefore the most significant amount is released on the acceleration phase following. High brake pad temperatures, result in a bimodal distribution with the first peak being at 1μm and the second falling at the nanometer scale at 200 nm. The ambient temperature appears to have a negligible effect on the particle generation.