The most commonly-used FFP masks are particle filtering FFP masks, which are available in protection classes FFP 1, FFP 2 and FFP 3. A higher protection class means that the mask filters harmful substances from the air more effectively and has a lower total leakage, which is the sum of all leakage points of the mask. 
FFP masks are worn in various industries to protect against substances in the air that are hazardous to health.
In the metal industry, masks prevent various types of metal smoke particle, sparks and dust from entering the respiratory tract, which can be caused, for example, by welding or cutting. But FFP masks are also used in the construction industry and in waste disposal and agriculture because they can provide protection against solid and liquid particles in the form of smoke particle, droplets, dust and sparks.