In some parts of the world, masks that have an exhalation valve have been banned. We tell you why experts say they are not effective in the context of a pandemic
One of the discussions that took the longest to settle at the beginning of the pandemic revolved around the usefulness of masks as a measure to avoid the spread of SARS-CoV-2.
However, now that the World Health Organization (WHO) advises governments to encourage the general public to use them where there is “widespread transmission and physical distancing is difficult” and as part of a series of prevention measures, that include hand washing and social distancing, the debate seems to have shifted to the effectiveness of a particular mask model: the one with a valve.
Do these face masks work or not to slow the advance of the pandemic? Do they protect us more than those without? And why have they generated controversy?
There are several masks on the market that come with a valve in the center or on one side (the N95, FPP2 and FPP3 have one).
But regardless of the model in question and what percentage of particles each filter, no valve mask is effective at context of a pandemic, experts warn.
This is because this kind of mask protects those who use it, but not others, since it filters particles from the outside air when the person inhales, but allows particles to escape through the valve when the person exhales.
That is to say, if the person using it is infected, can expel droplets with the virus when exhaling, and put other people at risk.
So much so, that in June the director of the Center for the Coordination of Health Alerts and Emergencies (CCAES) and spokesman for the Ministry of Health on the pandemic in Spain, Fernando Simón, labeled these types of masks as “Selfish”, precisely to protect only those who wear it.
“The problem with the valve is that the air exhaled by the person wearing it concentrates it at a specific point. That can cause someone who is exposed to that air to become infected, “he explained.
“May be the selfish masks because I protect myself and the others worry me little, “he added.
In the opinion of Ben Killingley, specialist in emergency medicine and infectious diseases at University College Hospital in London, United Kingdom, although the general use of the mask has the dual purpose of protecting both parties, “the reason why It promotes is so that the drops exhaled by people who may be infected and do not know it do not reach others ”.
And, from this point of view, it makes no sense to use valve masks in the community context.
“Actually, only respirators, which fit well to the face, have valves, and these are reserved for healthcare professionals. The public has had access to them, but the recommendation for people is to use the basic surgical face masks, and not these types of masks that do not provide any added benefit for them, ”emphasizes Killingley.
Not recommended, except in some cases
Since protection works only one way, the Centers for Disease Control and Prevention in the US (CDC), which months ago preceded the World Health Organization (WHO) in recommending the use of masks, he also cautioned against their use.
Likewise, authorities from different regions in Spain, where the use of masks is mandatory even on the street, have banned this type of respirator in some circumstances.
And in many parts of the world – including some airlines – they are not allowed into closed spaces with them.
What are valve masks made for then?
“The idea of including a valve that closes when you breathe in and opens when you exhale is to make them more comfortable for the healthcare worker who uses them”, Killingley explains.
“These masks are more comfortable to use, because they allow a better air circulation ”.
By allowing air to escape, the valve helps to regulate the temperature and prevent the fabric from getting wet.
That is why they are useful if one is, for example, on a construction site, a workshop, or anywhere where dust is generated, to avoid breathing these particles.
The other exception is, as we mentioned before, the case of health workers, who may be in contact with infected people, and where the goal is for them not to become infected.
Still, the CDC makes it clear that hospital personnel cannot use them in environments that must remain sterile (such as during an invasive procedure or in an operating room), as the valve “allows unfiltered exhaled air to enter. in the sterile environment.
And for other procedures, when health workers use this type of mask with valves, they usually do it accompanied by a protective mask.