Airway protection
The EN 149 standard defines the general requirements for respiratory protective devices, particularly filtering half masks against particles. The Average Exposure Value (AEV) corresponds to the concentration of a substance in the air in a given environment and is calculated for a reference period. The exposure limit is the level to which an individual can be exposed without risk to their health. If the ELV is reached or exceeded, protection is required. Masks are classified into categories:
• Class 1 (P1 or FF1) for protection against coarse solid particles with no specific toxicity (carbonate or calcium).
• Class 2 (P2 or FF2) for protection against hazardous or irritating solid and/or liquid particles (silica, sodium carbonate).
• Class 3 (P3 or FF3) for protection against toxic solid and/or liquid particles (beryllium, radioactive particles).
