July 10, 2020 9h36
No, masks do not prevent oxygen to pass
The Detector rumors
DETECTOR RUMORS / So that the cover face is more than ever recommended, the debate on the fact that it would be detrimental to the breathing to the surface again. The Detector of rumors, wondered what was said of the studies carried out with workers and even sportsmen.
The origin of the belief
Of the inhabitants of Florida, a u.s. State that bat in these days of the records of new cases of COVID-19, have recently expressed their discontent about a possible mandatory wearing of masks in public spaces where the detachment physics is difficult. There, as in Quebec, some suggest that the mask would be nothing less than a serious risk to health “by reducing the oxygen level in his blood” and the exponent ” to excessive levels of carbon dioxide “. Some even speak of cerebral hypoxia and hypercapnia, an increase of the partial pressure of CO2 in the blood. The belief was also circulated in other forms last may and has been déboulonnée in several languages. Memes circulate also, who were startled by those who are accustomed to wear masks year-round.
Indeed, there are many workers forced since long to wear a mask procedural (N95, P100, etc.) in the exercise of their functions, especially in areas of health and construction. These workers have been the object, over the decades, numerous studies in peer-reviewed science. No mention of hypoxia related to the wearing of the mask. None evokes more a higher fatality rate among these workers.
A review of the literature published in 2016, is interested in the various physiological measures likely to be influenced by the wearing of a mask for respiratory protection. The heart rate, one of the parameters most studied, seems to be little increase in the different studies. This means that the heart of a masked gunman has not had to make a further effort to supply the body with oxygenated blood.
In a small study published in 2013, 20 participants in their twenties had to provide moderate effort for an hour on the treadmill (5.6 km/h). The researchers concluded that the wearing of a N95, regardless of its type (with or without valve), had a minimal effect on the heart rate and the respiratory rate compared to a situation without a mask. The authors add that these lower increases are generally well-tolerated by healthy people.
Even if the studies have not progressed that far, we can assume that the difference with a mask craft would be negligible, if difference there was. Because the essential element to remember is that the mask does not prevent the air to pass. An oxygen molecule is sufficiently small to pass between the meshes of the net : the purpose of the mask is to stop the droplets that can contain viruses — and that, at the microscopic scale, are much larger than a molecule of oxygen or CO2.
In response to the many messages they have seen on social media, some have done the test. In South Carolina, Dr. Megan Hall, released 23 June photos of herself with four different types of masks and an apparatus for measuring the level of oxygen in the blood and heart rate (a pulse oximeter, or pulse oximeter, a small device that is placed at the end of the finger). The measures are, ” she said, almost identical, between 98 and 99 % (a normal level of oxygen in the blood has traditionally been estimated to be between 95% and 100%). “Keep in mind, says Dr. Hall, that before this I had worn the surgical mask for five hours “.