Many production areas include tasks executed in the area of dust, paints and other - much more dangerous - substances. In such cases, it is applicable that the employee executing the task is protected against aerosols and fine dust and corresponding health hazards. The people will be supplied with breathing gas via a respiratory protective device or must even, like astronauts, wear totally sealed protective suits. In order to save space, compressed air is often stored in bottles - utilizing respiratory air compressors. The compressed air must comply with high purity criteria for use as respiratory gas.