which are useful, which are futile?

The most effective option for healthcare professionals is the filtering respiratory mask, better known in France as the FFP1, FFP2 or FFP3 mask (filtering facepiece). In the United States, they are referred to as N95, N97, N99 and N 100 depending on their degree of filtration.

The INRS specifies that these devices consist of a filtering mask which guarantees the seal between the external atmosphere and the inside of the mask. The overall effectiveness of a respiratory protective mask depends both on the effectiveness of the filter material but also on the spill on the face.

These masks are classified (from FFP1 to FFP3) according to their performance, based on tests carried out with an aerosol of particles of 0.6 μm in median diameter (particles from 0.01 to 1 μm):

• FFP1 masks filter at least 80% of aerosols (total inward loss <22%).
• FFP2 masks filter at least 94% of aerosols (total inward loss <8%).
• FFP3 masks filter at least 99% of aerosols (total inward loss <2%).

The more efficient the filter, the more it opposes the passage of air. For this reason, some masks have valves or valves for better breathing comfort.

Although a 2019 study did not find a significant difference between surgical masks and FFP2 masks in reducing the rate of laboratory-confirmed influenza in healthcare workers, other work concluded that FFP2 masks are superior to surgical masks in terms of reduced exposure. to aerosols and viral transmission. Considering the recent supply shortage and rising prices, it is reassuring that FFP2 masks that are past their expiration date will retain their filtration efficiency after being sterilized with ethylene oxide and peroxide. of hydrogen.

But this efficiency has a “cost” in terms of working comfort. FFP2 masks were described as “stuffy, uncomfortable, and difficult to tolerate for long periods of time” in a recent JAMA comment, and prolonged wear can lead to facial bruising and abrasions.