1. Principles of respiratory protective equipment (RPE)

There are two main operating principles (figure 1 ):

• devices whose operation depends on the surrounding ambient atmosphere, i.e. the wearer is supplied with purified ambient air taken from the immediate environment;

• equipment that operates independently of the surrounding atmosphere, i.e. the wearer is supplied with breathable gas from a source whose quality is unrelated to the ambient atmosphere in his or her immediate environment. This type of equipment is essential when the oxygen content of the surrounding environment is uncertain or below 17%.

We'll see later that these two equipment families can be broken down into sub-families, generally distinguishable...