WARNING ! Contrary to what current communication fails to say, cloth masks do not protect from SARS-CoV-2 (COVID-19) as explained by the INRS.

A few weeks ago you were told that you did not need masks (and for good reason, there were none). Today we need to get people back to work, we offer fabric masks. What will we tell you tomorrow?

In the context of working in an enclosed environment or when you are in the presence of work colleagues and customers, the risk of contamination increases according to your protection, the health and safety rules that you follow. Wearing the fabric mask gives you a false sense of protection. Only masks type FFP2 and more offer a guarantee of protection of SARS-CoV-2 if you follow the instructions for use.


1 - The National Research and Security Institute (INRS) is explicit *

INRS: "These masks have not been subjected to all the efficiency tests prescribed by the standards in force. The few scientific studies on the filtration performance of cloth masks show a filtration efficiency lower than that surgical masks. A study among hospital staff also showed that the risk of respiratory infection was higher in the group wearing a tissue mask than in the group wearing a surgical mask."

2 - Annals of Internal Medicine (South Korea)

Study shows that surgical masks and cotton masks are not effective in preventing the spread of SARS-CoV-2. The study, conducted in two hospitals in Seoul (South Korea), found that when Covid-19 patients coughed in either type of mask, droplets of the virus were released into the environment and outer surface of the mask. The findings were published in Annals of Internal Medicine.

Researchers from the Asan Medical Center and the University of Ulsan College of Medicine in Seoul asked 4 patients with Covid-19 to cough 5 times each on a petri dish. They performed this maskless operation with a surgical mask and cotton. Then by studying the surface, the researchers realized that in all cases SARS-CoV-2 is present. These results suggest that recommendations to wear masks to prevent the spread of Covid-19 may not be effective. The researchers also note that they found more contamination outside than on the inside surfaces of the mask. Alternatively, small aerosols of SARS-CoV-2 generated during a high-speed cough could enter the masks.

3 - A choice dictated by the shortage

INRS: "Faced with the shortage of masks, companies and laboratories have mobilized to select the materials likely to allow the production of alternative masks in the context of the fight against Covid-19. The Directorate General of Armaments realizes filtration efficiency and permeability tests. Tissue performance results are available available."

We can ask questions:

  • - Why does the Directorate General of Armaments perform performance tests instead of a laboratory specializing in respiratory protection ?
  • - We are talking about AFNOR specs or standards which are in reality manufacturing advice that everyone can achieve at either but which are in no way a certification on filtration efficiency.
    Is it sufficient ?
  • - Where are the certifications, methods and figures?

(It may remind us of our collective memory, the overly visible madder red pants, which French soldiers wore when war broke out in 1914 as a symbol of French preparation for modern warfare.)

4 - How does SARS-CoV-2 Coronavirus spread through the air?

To understand why face masks might work, it is important to look at how the virus that causes Covid-19 spreads in the first place.

Once it has infected someone, the Sars-CoV-2 virus responsible for the disease hijacks their cells to replicate itself. As it multiplies, these new virus particles then burst out of the cells and become suspended in the bodily fluids in our lungs, mouth and nose. When an infected person coughs, they can send showers of tiny droplets – known as aerosols – filled with the virus into the air.

A single cough can produce up to 3,000 droplets. There are fears the virus can also be spread simply through speaking. One recent study showed that we spray thousands of droplets invisible to the naked eye into the air just by uttering the words “stay healthy”.

Once out of our mouths, many of the larger droplets will quickly settle onto nearby surfaces while smaller ones remain suspended in the air for hours, where they can be breathed in. While the behaviour of the virus-filled droplets in rooms with air conditioning and outside environments are less well understood, they are thought to settle on surfaces more quickly in disturbed air. There are also some reports that the coronavirus can spread through ventilation systems in buildings. (Read more about how long coronavirus survives on surfaces.)

The Sars-CoV-2 virus has been found to survive in these aerosol droplets for at least three hours, according to one study by virologist Neeltje van Doremalen and her colleagues at the US National Institute of Allergy and Infectious Diseases, Hamilton, Montana. But a more recent, but as yet unpublished study, has found that the Sars-CoV-2 virus is still infectious for more than 16 hours after being suspended in aerosol droplets. It found the virus was “remarkably resilient in aerosol form” compared to other similar coronaviruses they studied.

Together, they suggest that in the right conditions, the virus can linger in the air for several hours and still infect people if breathed in. And in indoor environments, they seem to be particularly prone to spreading through the air.

An unpublished analysis of 318 outbreaks of Covid-19 in China showed that it was most commonly transmitted in indoor environments, particularly in people’s homes, but also on public transport, in restaurants, cinemas and shops. They found just one example where the virus appeared to have been transmitted while people were outside.

Genetic material from Sars-CoV-2 has also been detected in the air in toilets and rooms used by people infected with Covid-19. One study of a cluster of cases that occured in a restaurant in Guangzhou, China, suggests that in poorly ventilated spaces the virus can spread to people sitting in the immediate vicinity through airborne aerosol droplets.

• Postilion droplets> 5µm: droplets quickly fall to less than a meter (unless coughing: maximum expiration speeds can reach up to 10-30 m / s, creating a cloud that can extend over approximately 7-8 m source: American Medical Association)

• Micro-drops> 2.5µm and aerosolized virus (0.25 to 1µm diameter in a contaminated environment) remain in the air for a long time (several hours), transported by air current, inhaled deep source : bioRxiv

The Directorate General of Armaments has carried out performance tests (the figures and the method of which have not been found) for particles of 3 µm which correspond to large droplets which are projected while COVID-19 has dimensions between 0.14 to 0.06µm and therefore end up in micro-droplets.

Transmission of COVID19 by aerosol, implications for public health and deconfinement (fr).

SRAS-CoV-2 dimensionSARS-CoV-2 (yellow),

dimensions covid-19

5 - Cloth masks, good or bad idea?

The communication on these masks suggests that one is sufficiently protected which can cause a loosening of the protection by gestures of hygiene and social distancing and particularly in the context of work.

These masks can protect against projections of large droplets emitted by a person opposite at the time. In the absence of a mask, it can be useful in the context of confinement when you go out to buy bread or go shopping, provided that you wash your mask as soon as you return home. According to the recommendations, this mask should be changed every 3 hours. The moisture accumulated by breathing and the environment will contaminate and contaminate the mask and can promote the proliferation of viruses. In addition, it is regularly repeated that a mask, conventional or artisanal, is ineffective if one touches it, fiddles with it, moves it, moves it ... which is frequently the case especially in the context of work!

In addition, these masks must be washed every evening at 70 ° C (with limited use due to the deterioration of the fabric fibers)

*Source : INRS - Respiratory protection masks and biological risks: frequently asked questions (fr)

source : BBC Why we should all be wearing face masks