This European Standard specifies requirements for the quality of compressed gas supplied for use with the following applications: a) respiratory protective devices - Self-contained open-circuit compressed gas breathing apparatus and self-contained open-circuit compressed gas underwater breathing apparatus; b) respiratory protective devices - Compressed gas line breathing apparatus and compressed gas line breathing apparatus for use under water; c) respiratory protective devices for escape - Self-contained open-circuit compressed gas breathing apparatus including full face mask or mouthpiece assembly or hoods; d) respiratory protective devices for escape - Self-contained re-breathing apparatus including full face mask or mouthpiece assembly or hoods; e) respiratory equipment - Self-contained re-breathing apparatus; f) breathing gas supplied for hyperbaric operations. The standard also applies to synthetic air. Account is taken of the use of compressed gases at both normal atmospheric pressure and hyperbaric pressures. Maximum allowable concentrations of impurity for compressed gases are quoted as values at normal atmospheric pressure. This European Standard does not apply to compressed gases used for medical purposes or for aerospace applications.