After the World Health Organization (WHO) discouraged the use of valve masks as a barrier against coronavirus, both among health care workers and in the general population, doubts have arisen as to which are the most effective mouthguards for protect yourself in the pandemic.
WITHOUT VALVE
In a new guide of recommendations, the WHO stressed that the use of facial coatings possessing removable valves or filters, used mainly by construction workers, is “inefficient” or “useless” to contain the spread of viruses, as that the user could exhale insufficiently filtered air.
“The danger is that if you wear a masked valve and you are infected you may be expelling infected aerosols. In other words, it nullifies the purpose of wearing a mask. It is not dangerous for you, but it simply nullifies the purpose.” explained WHO emergency director Michael Ryan, quoted in a bulletin from the entity.
This is the agreement of the US Centers for Disease Control and Prevention (CDC), which in August warned that “holes in the material can allow respiratory droplets to escape and reach other people.”
A study by the US National Institute of Standards and Technology last November also found the inadequacies of this facial coverage model to stop coronavirus
In analyzing high-speed videos, engineer and researcher Matthew Staymates evidenced the behavior of airflow through masks with or without exhalation valves.
These valves do make masks easier to breathe and more comfortable, but they are only “appropriate when they are intended to protect the user,” such as hospital workers from infected patients.
However, the WHO has been emphatic in that health care workers should wear medical masks without valves in the face of the results of these studies.
MEDICAL AND NON-MEDICAL: WHO USES WHICH?
In this line, the WHO continues to recommend to all health personnel the use of medical masks (the usual ones in operating rooms, for example) in areas with a lower risk of airborne infection (by aerosols) and those with greater protection (N95, FFP2 , FFP3) in high-risk areas, such as areas of care for patients with covid-19.
Such mouthguards are also advisable for at-risk groups such as the elderly and people with chronic lung disease, cancer, diabetes or cardiovascular problems, in contexts where the physical distance of at least one meter or adequate ventilation cannot be guaranteed. .
The WHO suggests the use at all times of medical masks to caregivers and other people who share space with suspected or confirmed covid-19 patients. This type of medical equipment has been limited to these groups to avoid their scarcity and encourage reasonable use.
For the general public, in areas of community-based coronavirus transmission, the WHO recommends the use of non-medical masks (even cloth masks) in indoor areas such as shops, offices or schools, if not possible. ensure a physical distance of at least one meter between those present or good ventilation.
Beyond the type, the organization has insisted that the use of mouthpieces should be mandatory and, above all, combined with other measures: hand hygiene, physical distance of at least one meter, avoid touching the face , cover yourself by coughing or sneezing, ventilate indoor environments and perform contact tracking, quarantine and isolation.
“Only a mask, even when used correctly, is insufficient to provide adequate protection or control of the source,” the WHO adds in its most recent guide.
CLOTHES YES, BUT WITH THREE LAYERS
On fabric masks, the WHO has made it clear that the truly effective ones are those that are made with three layers: an interior that allows the passage of moisture, a filter intermediate and a waterproof exterior.
However, the scientific director of the Society of Infectious Diseases of Brazil, José David Urbaez Brito, pointed out that this type of mouthpiece “has a shelf life of three to four hours, as respiratory secretions are moistening these tissues, especially cotton And a damp fabric loses its identity as a barrier. “
In this line, the WHO warned that masks of this type that are manufactured industrially “must meet the minimum thresholds related to the three essential parameters: filtration, breathability and fit.”
In its terms, the WHO further clarified that masks or visors, while providing eye protection, “should not be considered as an equivalent of masks in terms of protection against respiratory droplets. “.
HAVE THE CHILDREN USED A MASK?
The WHO reiterated that children under the age of 5 should not wear masks, and that those between the ages of 6 and 11 should use them depending on factors such as community virus transmission and the social and cultural environment. .
In children over 12 years of age the same recommendations should be applied as in adults, according to the suggestions of the organization.
These suggestions should be weighed in clinical cases of immunocompromised children, with serious underlying illnesses such as cancer, or those with a mobility problem, disability, or special need.
SPORT AND FACE PROTECTION
Finally, the WHO has warned that people should not wear mouthguards during “vigorous-intensity” physical activity, as “they can reduce the ability to breathe comfortably.”
Instead, he recommended maintaining a physical distance of at least a meter with other people and ensuring good ventilation during exercise as a “most important preventive measure.”
“If the activity is carried out indoors, adequate ventilation must be ensured at all times by means of natural ventilation or a ventilation system that works properly or is maintained.”