In these rules are fixed the maximum values allowed for both the initial penetration through the dust filters (Grades P1, P2 and P3 ) for both the loss attributable to the inward face and possibly other components. Made clear , therefore, that within the facial and ‘ still present a certain concentration of pollutant due to both the penetration through dust filters both to the losses attributable to the inward face and other components, you stabiscono the following definitions :
protection factor (PF ) and ‘ the relationship between the concentration of the pollutant in the ambient air and the inside of the face , the height of the respiratory tract of the user; nominal protection factor ( FPN ) and ‘ the value of the protection factor when the penetration through the filters and losses inward assume the maximum values allowed by the rules ; protection factor of Operations ( FPO ) and the value on the basis of experimental data and prudential considerations ; is attributed to the protection factor for the choice of a respirator for use in the work environment .
It seems useful to further clarify the following:
the protection factor and ‘ by definition the parameter that expresses , in general, the entities’protection that a respirator offers the user ; the nominal protection factor and ‘ the value of the protection factor which must be guaranteed at the time of certification by the control bodies , with laboratory tests standardized and therefore reproducible ;
the protection factor and operating ‘ factor value of security to use in practice
operational work environment : this value – always less than or at most equal to the nominal protection factor – has the purpose of keeping cautiously into consideration the problems arising from the specific diversity ‘ concerning the various work environments , by the requirements of mobility’ operator , and the accuracy with which ‘ put on the respirator , etc. . ; what ‘ is especially true for devices which are associated with the most’ high values of protection.
For the different types of respirator is provided below the values of the FPN and those of FPO :
Respirator FPN FPO
Half mask with P1 filter (or filtering facepiece FFP1 ) 4 4
Half mask with filter P2 ( FFP2 or filtering facepiece ) 12 10
Half mask with filter P3 ( or filtering facepiece FFP3 ) 50 30
Full mask with P1 filter 4 5
Full mask with filter P2 20 15
Full mask with filter P3 1000 400
Elettrorespiratore Class 1 for use with a helmet or
cap ( THP1 ) 10 5
Elettrorespiratore Class 2 for use with helmet or
cap ( THP2 ) 20 20
Electrorespirator class 3 for use with helmet or
cap ( TIHP3 ) 500 100
Electrorespirator class 1 for use with mask
( TMP1 ) 20 10
Electrorespirator class 2 for use with mask
( TMP2 ) 100 100
Electrorespirator class 3 for use with mask
( TM3 ) 400 2000
The report that provides the maximum limit of exposure to a certain pollutant in function of the operating protection factor of the respirator and the exposure limit value adopted for asbestos and ‘the following :
maximum exposure limit = FPO x VLE
where with VLE and ‘ indicated the exposure limit value adopted .
If we consider eg crocidolite (VLE fibre/cm3 = 0.2 ), the protective factor operating on the half mask with combination filter P3 indicates that such a respirator will provide ‘ user a guarantee of protection up to a concentration of 6 fibre/cm3 . The use of a full face mask with P3 filter , or a Electrorespirator class 3 for use with mask, potra ‘ instead provide up to a concentration of 80 fibre/cm3 .
For the reclamation work , during which they are usually reached high concentrations of
Asbestos fibers are normally favorites ( also in relation to more ‘ favorable microclimatic conditions for the user ) and the turbo devices THP3 TMP3 . If these prove to be insufficient for the guarantee of protection which must be achieved must then be used , as mentioned earlier , insulating respirators with which can ‘be reached a value of the factor of protection operating equal to 1000 .
For occasional work ( generally limited maintenance or repairs ) which is not associated with a high release of fibers , the use of half-mask with a P3 filter provides sufficient guarantees ( without being unnecessarily oversized ) in relation to any incident that may result in significant – but temporary – concentrations of asbestos fibers into the environment.