BBOA samples were produced through the smoldering of pine wood with a methodology based on that described by Kim et al. . Untreated pine wood from a hardware store were cut into strips (~ 20 x 2 x 2 mm) and 1.2 g total mass of the strips were placed lengthwise inside a quartz flow tube (inner diameter 37 mm, outer diameter 40 mm, length 1100 mm). Pressurised room air from a compressor (Oil-free 380 Series, Thomas, Sheboygan USA) was passed through the tube at a flow rate of 2 l min -1 , controlled by a mass flow controller (MKS, Andover USA). A ceramic tubular heater (length 150 mm, Watlow, St. Louis USA) fitting around the flow tube moved along the length of the flow tube in the direction of the air flow at a speed of 10 mm min -1 , propelled by a custom-built motorized track, enabling a steady and controlled aerosol flow from the smoldering phase of combustion only. The heating temperature was controlled by varying the heater voltage, with 65 V used to access a temperature of 400 °C, as calibrated by a K-type thermocouple. Constraining the experimental conditions to feature only smoldering rather than flaming conditions led to no visible evidence of black carbon present in the particles (Fig. and).