Respiratory protective devices are protective devices intended to protect against hazardous substances in the aeriform state such as particles, vapours and gases by means of the filtering mechanism. These devices, which partially or completely cover the face, are made of filtering material or consist of a reusable structure fitted with replaceable filters. Each class features specific filters.
The EN 137 standard specifies the minimum performance requirements for self-contained open-circuit compressed air breathing apparatus with full face mask as respiratory protective devices. These do not include respiratory devices for escape purposes and for underwater use. This gear is intended for use in work situations where there is a low risk of over-pressurisation of the equipped cylinders, due to very hot environmental conditions.