Figure 2

Characterization of wood smoke particulate matter. (a) Scanning electron microscopy (SEM) image of wood smoke particles. (b) Size distribution graph of the particle size as assessed by photon correlation spectroscopy with the mean primary particle size indicated by the red line. (c) Average particle number size distribution in the exposure chamber, measured by SMPS system. The plot displays the distribution as mean and standard deviation from all 16 exposures. Previous studies demonstrate the 50–80 nm peak consists of alkali salt particles (e.g. potassium sulphate and potassium chloride) and the 150–200 nm peak soot particles with more organic material [15],[16]. (d) Electron paramagnetic resonance (EPR) signal intensity showing oxygen free radical generation from wood smoke particulates in the presence of the superoxide-selective spin-trap Tempone-H. Particulates from exposures collected on Teflon filters suspended in physiological saline solution at a concentration of 100 μg particles/mL. The standard reference material urban dust (100 μg particles/mL) and pyrogallol (100 μM) were used as controls. Data expressed as mean ± SEM (n = 4–5).