Nowadays, a large number of workers are asked to perform work in the presence of hazardous materials. These hazardous materials very often produce contaminants (in the form of particles, gas, vapour or smoke), which mix with the air in the workplace. In order to preserve workers’ respiratory health where there is contaminated air, it is essential to wear a respiratory protective device that is appropriate for the situation, and ensure that it corresponds with the contaminants in the air. It also requires being familiar with the proper operation mode and conducting the required maintenance in order to ensure that its level of efficiency is always at its maximum.