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On March 11, 2020, the WHO defined Covid-19 as a pandemic and almost two years old, we still don’t have a forecast of its end. With more than 18 million cases and 500,000 deaths in Brazil, the use of masks remains a fundamental preventive tool.
Use of respiratory protection in the clinic: is it still necessary?
A study carried out by the team at the University of Cambridge and its associated hospitals, evaluated the difference in contamination by Sars-Cov-2 between professionals who took care of patients with Covid-19 and those who did not. *)Before the research started, all professionals used fluid-resistant surgical masks of type IIR (FRSMs) as personal protective equipment and PFF3 masks they were only recommended for procedures with aerosol generation. With this routine, professionals in the Covid-19 ward had a 47 times higher risk of infection than professionals who did not care for patients with the viral infection. *)Therefore, the guidance was modified so that all professionals who dealt with patients infected with Sars-Cov2 used PFF3 masks and, with that, the The number of professionals affected by the disease in the Covid-19 ward became similar to that in the non-Covid-19 ward. In other words, this contamination was probably communal, which means that the PFF3 masks provided practically 100% protection and the surgical masks were insufficient. Although this is a small study, its findings emphasize the importance of using respiratory protection.
Contagion via aerosols: how to protect yourself from it? The Sars-Cov-2 is disseminated through the environment through particles that are expelled by the upper respiratory tract of the infected person (by speech, coughing and sneezing, by example) and the greater the exhaled force, the greater the number of particles are expelled. Most of these particles are smaller than 10 microns in diameter and are called aerosols. Aerosols are able to remain in suspension for longer, which increases the chances of contamination, especially in closed environments, without ventilation and in close proximity to people. In addition, much evidence indicates that the coronavirus is also transmitted by droplets, which do not reach distances greater than 1.5/2 meters.
For protection against aerosols, PFF masks are ideal. However, as exposed, all masks reduce the amount of droplets that go into the environment, even the simplest ones. To increase the filtering capacity of simpler masks, what can be done is to use two cloth masks with a double layer each, or one cloth and one surgical mask for periods of no more than four hours.
PFF and elastometric masks: what are they?
The masks must work as a double barrier, preventing both the dispersion and the aspiration of particles. The PFF nomenclature refers to the “filtering facepiece” and, in Brazil, there are three types: PFF1, PFF2 and PFF3. Such numbering concerns the ability to filter particles from the environment by the mask.
- PFF1: filters 80% of the particles.
PFF2: filters 94% of the particles. (Note: N-95 is the American denomination, filtering 95% of the particles, having a role equivalent to PFF2). PFF3: filters 99% of the particles.
PFF masks have, in addition to the filtering fabric, electrostatic properties that enhance the retention power of particles. It is also worth noting that models with valves are not recommended, as they only filter the sucked in air, not treating the expired air. In this way, large amounts of particles are eliminated in the environment and, if used by someone who is sick, it can infect other people.
Read too: Analysis of oxygen saturation in elderly people using face masks
In addition to offering greater protection against aerosols, PFF masks have greater durability, and can be used for up to 8 hours without the need to change. PFF2 can even be used more than once, as long as it is left in a ventilated place after use, preferably in the sun, for up to three days before reusing it. In this way, it would be possible to use it for up to a month.
Physician on duty at the CTI of the São Sebastião State Institute of Infectology ⦁ Physician at the Dia Hospital of the Evandro Chagas National Institute of Infectology/FIOCRUZ ⦁ Infectologist at the Evandro Chagas National Infectious Institute/FIOCRUZ ⦁ Master’s Student in Clinical Research at the National Institute of Infectology Evandro Chagas/FIOCRUZ ⦁ Graduation in Medicine from the Fluminense Federal University See more benefits of being a PEBMED Portal user: See more benefits of be a user
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The PEBMED Portal is intended for
doctors and other health professionals. Our contents inform recent panoramas of medicine.
If you are interested in publishing your curriculum on the internet, connecting with patients and increasing your differentials, create a free profile on AgendarConsulta, the partner site of PEBMED.
If you are interested in more contents and courses focused on medical residency, get to know Medcel, the partner site of PEBMED