. Engine dust samples (n = 13;
sample mass: 0.6–1.4 g) from several engine types were collected
from the mixer shroud surrounding the turbine blades, onto which
some PM in the exhaust emissions impacts directly during routine
engine function, leading to a slight accumulation over time (BA Engineering,
pers. comm.). Brake dust samples (n = 16; sample mass:
0.75–3.5 g) were collected from the wheel hubs of these aircraft.
Brake lining wear occurs most commonly during landing and less