DUSTS are airborne solid particles with variable dimensions, which are generated during
crushing process of organic and inorganic solid substances.
MISTS are airborne droplets which are created when a fluid evaporates and then
condenses or with a mechanical nebulization (they can have an aqueous or organic base).
FUMES are particles generated from evaporating or fused metal secondly quickly cooled,
with very small dimension inferior to 0,4 μm; they generally are generated during combu-stion, fusion or welding processes.
Therefor dusts are airborne solid particles that need a
mechanical/electrostatic filter to be removed from the air.
They are two types of particle filtering devices: the filtering half pieces, specified as FFP, and the masks (full facor half mask) equipped with filters, specified as P.
The reference standards are the EN 149 for particle filtering half pieces and the EN 143 for the particle filters coupled with masks.
Depending on these standards, the particle filtering devices are tested and then classified in three classes with an increasing filtering capacity.
The EN 529:2005 European Standard gives information about the right selection and use of
a respiratory protective device depending on risk assessment.
In that standard is given the definition of the “protection factor”, which is the ratio between the contaminant concentration outside the mask and the contaminant concentration inside the mask.
This standard also defines the “Workplace Protection Factor” (WFP), resulting from analysis
in real workplace situations, far more realistic and valuable than the “Nominal Protection
Factor” (NPF).
*TLV = Threshold Limit Value of a chemical substance defines a reasonable level to which a worker can be exposed without adverse health effects.
If the contaminant concentration in the workplace is unknown, it is possible to select the
minimum protection level using the indications of the following table:
