Which face masks are the most effective and how to use them correctly?
The most effective type of mask depends on what you want to use it for. Each situation requires a different type of mask. We have three types: Self-filtering masks are designed for healthcare personnel or those in direct contact with the virus, or in areas with a high viral load; they have a filtering capacity of 0.3 microns. They are what we call FFP2 and FFP3.
Surgical masks, as their name suggests, are intended to be worn in an operating room. They are used to prevent professionals working in the operation from contaminating the patient being operated on, and have a hydrophobic surface treatment to prevent any fluid splashes that may occur during the procedure from entering the professionals’ mouths. They have a bacterial protection efficiency of 98% and a breathability of less than 40 %. They should be used by people at risk, who are infected with coronavirus and in hospital environments, and the recommended use time is four hours.
Finally we have hygienic masks, among which we find the non-reusable and reusable ones. The non-reusable ones are very similar to surgical masks, although the bacterial protection effectiveness is 95 %. In the case of reusable masks, the main advantage is that they can be washed and reused a certain number of times, thus helping to reduce their environmental impact. The bacterial protection efficiency can be 30% or more and the breathability is less than 60 pascals per square centimetre. The recommended wearing time is one day and it is important to wash the mask at a temperature of 60ºC for one hour at the end of the day.
«Fitting the mask is essential, even more important than the type of protection we use»
If we are in a poorly ventilated place where there may be a higher viral load, a self-filtering mask would be recommended. In places with sufficient ventilation and where the safety distance is maintained, a reusable hygienic mask is more than enough. But we must also keep in mind that masks must be worn properly, covering the nose.
This is why fitting the mask is essential, even more important than the type of protection we use. If air is leaking sideways when we breathe, it has not been filtered. If your goggles fog up, it is a sign of a bad fit, because unfiltered air is coming out. We recommend masks with an adjustable nosepiece, but bear in mind that a properly fitted mask will not be comfortable because it will pull on our ears. In this sense, safety and comfort do not go hand in hand.
Answered by Enric Carrera, director of the Institute of Textile Research and Industrial Cooperation (INTEXTER) of the Polytechnic University of Catalonia (UPC).
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