This International Standard specifies sampling, cleanup and analysis procedures for the determination of polycyclic aromatic hydrocarbons (PAH) in ambient air. It is designed to collect both gas-phase and particulate-phase PAH and to determine them collectively. It is a high-volume (100 l/min to 250 l/min) method capable of detecting 0,05 ng/m3 or lower concentrations of PAH with sampling volumes up to 350 m3. The method has been validated for sampling periods up to 24 h. Precision under normal conditions can be expected to be _ 25 % or better and uncertainty _ 50 % or better (see annex A, Table A.1). This International Standard describes a procedure for sampling and analysis for PAH that involves collection from air on a combination fine-particle filter and sorbent trap, and subsequent analysis by gas chromatography/mass spectrometry (GC/MS).