Volatile organic compounds were determined according to ISO16000-6 (ISO, 2011) by adsorption on Tenax® TA filled stainlesssteel tubes, thermal desorption at 290 °C (TD 100, Markes International,UK) and subsequent GC/MS analysis (GC 7890, MS 5975C, Agilent Technologies, USA) using a J&W Scientific DB-5MS column (L = 60 m; I.D.= 0.25 mm; film = 0.25 mm). Calibration was carried out with internal and external standards, whenever possible against pure reference compounds (some substances, e.g. piperonal, are regulated as drug precursors and are therefore not available). The air sampling volume was between 0.5 l and 4 l, depending on the expected chamber concentrations.