Llantrisant, Wales, UK) that trap VOCs. For the analyses, the desorption tubes were placed inside a thermal desorption unit (Marks Unity desorption unit, Markes International) and subsequently heated to 270 C in order to release all VOCs onto the gas chromatography capillary column (RTX-5ms, 30 m × 0.25 mm 5% diphenyl, 95% dimethylsiloxane