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.
The EN 403 standard refers to filtering devices with hood for self-rescue from places with particulate, such as carbon monoxide or other toxic gases produced by fire. It specifies the minimum requirement for this single use apparatus. It does not apply to devices intended to be used under circumstances where there could be oxygen deficiency (lower than 17% in volume).