Particle-filtering half masks FFP masks are part of the personal protective equipment PPE in the context of occupational safety and are intended to protect the mask wearer from particles, droplets and aerosols. The design of the particle filtering half masks is different. There are masks without an exhalation valve and masks with an exhalation valve. Valved masks filter both the inhaled and exhaled air and therefore provide both self-protection and external protection, although they are primarily designed for self-protection. Masks with a valve only filter the inhaled air and therefore offer no external protection.utz.
