Methods:
A scanning mobility particle sizer spectrometer (SMPS, TSI model 3936) with a sheath flow rate of
4 Lmin−1 and an aerosol flow rate of 0.4 Lmin−1
for measuring size-resolved number concentrations of mobility diameter
particles 12–600 nm, and an aerodynamic particle sizer
spectrometer (APS, TSI model 3321) for measuring size
resolved number concentrations of 0.5–19 µm aerodynamic
diameter particles. SMPS and APS size distributions were
merged to give a continuous aerosol distribution from 0.01
to 2.5 µm (aerodynamic diameter) using previously established
methods (Khlystov et al., 2004), assuming a density
of 1.5 g cm−3 and shape factor of 1.