Figure 1

Characterisation of brake wear particles. A) shows a typical contribution of measured brake particles from a braking simulation with 8 repetitions, „normal deceleration“. B) shows the particle number, mass and surface concentrations in the air of different braking behaviours. Values represent the sum of all concentrations measured during one run ("sum under the curve"). Such a representation enables a better comparability among runs with different exposure times. SD represents the standard deviation. §p < 0.05, §§p < 0.01 represent a statistically significant influence of the fixed factors. + stands for p < 0.05, ++ for p < 0.01 in pairwise Bonferroni t-tests of designated braking conditions in comparison with the "full stop 8x". C) and D) represent identical illustrations with measured metals and carbon components. Displayed are the means and the standard deviations from 2 ("full stop 4x") or 4 (all the other conditions) experiments. Standard deviations for the elemental carbon could not be calculated for all bars because of values below the detection limit.