A total of 74 high volume air samples were collected at a background site in Czech Republic from 2012 to 2014 in which the concentrations of 20 per- and polyfluoroalkyl substances (PFASs) were investigated. The total concentrations (gas + particle phase) ranged from 0.03 to 2.08 pg m(-3) (average 0.52 pg m(-3)) for the sum of perfluoroalkyl carboxylic acids (Sigma PFCAs), from 0.02 to 0.85 pg m(-3) (average 0.28 pg m(-3)) for the sum of perfluoroalkyl sulfonates (Sigma PFSAs) and from below detection to 0.18 pg m(-3) (average 0.05 pg m(-3)) for the sum of perfluorooctane sulfonamides and sulfonamidoethanols (Sigma FOSA/Es). The gas phase concentrations of most PFASs were not controlled by temperature dependent sources but rather by long-range atmospheric transport. Air mass backward trajectory analysis showed that the highest concentrations of PFASs were mainly originating from continental areas. The average particle fractions (theta) of Sigma PFCAs (theta = 0.74 +/- 0.26) and Sigma PFSAs (theta = 0.78 +/- 0.22) were higher compared to Sigma FOSA/Es (theta = 0.31 +/- 0.35). However, they may be subject to sampling artefacts. This is the first study ever reporting PFASs concentrations in air samples collected over consecutive years. Significant decreases in 2012-2014 for PFOA, MeFOSE, EtFOSE and Sigma PFCAs were observed with apparent half-lives of 1.01, 0.86, 0.92 and 1.94 years, respectively.