In a wave of increased attention to the Chinese coronavirus and the increased demand for medical masks and other individual respiratory protection, I decided to clarify for myself – what kind of respirators are, how they work and what they protect against.
It turned out that masks have three degrees of protection:
Who looks at this when buying a respirator to work with cement or mineral wool?
Respirators can be fitted with or without a valve. Respirators can be equipped with additional layers of protection against something specific, such as certain types of aerosols, organic solvents, welding gases and the like.
Respirators are really disposable. And this disposability does not always mean working all day. Depending on the air pollution, it may be necessary to change the mask after 2 hours! Especially if it is a mask without a valve and humidified by exhaled air.
The main parameter of a mask or respirator is its degree of cleaning or FFP protection class.
FFP1 respirators have low filtration efficiency and up to 80% degree of protection, protecting only against large solid aerosols (coarse dust). They allow respiratory protection up to 4 MPCs (maximum allowable concentrations of contaminants).
They are used at work with non-toxic dust, at construction, woodworking, well protect from particles of cement, pollen, coal, metal sawdust and similar coarse dust particles.
FFP2 respirators clean up to 94% of dirt, have average efficiency and in addition to the above mentioned dirt, they filter fine and liquid aerosols. They are used for air pollution of up to 12 MPC, for dust of medium toxicity, hardwood dust, coal, electric welding, catch liquid aerosols based on oil and water.
FFP3 respirators are highly effective, clean up to 99% of impurities, allow you to work with contamination of up to 50 MAC (according to other data up to 30 MAC) and protect the respiratory system in addition to the above mentioned contaminants also from fine solid and liquid aerosols. They are used for handling toxic dust, asbestos, radioactive dust and for protection against bacteria and viruses, catching spores of mold.
What about the length of their work?
The important question is what about the length of their work?
Depending on the degree of air pollution and working conditions, non-valve breathing apparatuses are effective up to 2 hours according to some data, and valve-operated respirators up to 8 hours.
After that, their effectiveness is reduced due to moisture from breathing. It would seem that the bad in a wet mask, damp cloth or membrane may even better start filtering dust?
Well, it wouldn’t. The principle of such respirators is electrostatic filtration.
Dust particles stick to the membrane, not just mechanically stopped by the small pores in the membrane. A moistened mask loses its electrostatic properties and begins to work much less efficiently, simply as a mechanical filter.
On the other hand, the mark D means that the mask has been tested to filter dolomite dust for 8 hours, but most likely without taking into account moisture from breathing and loss of electrostatic properties.
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