To further protect against the spread of the coronavirus in the air, US health authorities recommend wearing two superimposed masks or a tight-fitting surgical mask, they explained in a study published on Wednesday.
The mask significantly reduces the exhalation of droplets from infected people and reduces exposure to these particles in uncontaminated people, the US Centers for Disease Prevention and Control (CDC) reminded in this study.
Over 92% protection with two superimposed masks
But cloth masks and surgical masks are looser than KN95 (or FFP2) masks, increasing the risk of air escaping from the sides. In January, the CDC did lab simulations of reducing leaks with a fabric mask overlaid on a surgical mask, and then with a surgical mask with elastic bands tied near the edges that are folded inward.
While the non-tied surgical mask and the cloth mask block only 42% and 44.3% respectively of the aerosols dispersed by a cough, the combination of the two rises to 92.5% protection. In another experiment, exposure to an unmasked infected person was reduced by 83% with a double mask and by 64.5% with a face-tie or plastic mask, or nylon neck warmer worn over a surgical mask. “This means that these masks work and that they work best when they are adjusted and worn correctly,” said Rochelle Walensky, director of the CDC, during a press briefing.
Wearing a mask, the best weapon against the coronavirus
The CDC will update their public information on masks with these new options. As new, more contagious variants of the coronavirus spread in the United States, these experiences support previous studies on the need to wear better quality masks, meeting more stringent standards or overlaid masks.
The scientific community now agrees that the virus is mainly diffused in the air, and there is growing evidence that very fine droplets, can be thrown up to several feet when someone speaks or breathes. “Research has shown that infections and deaths due to Covid-19 are decreasing” thanks to the general wearing of the mask, added Rochelle Walensky. “With contaminations, hospitalizations and deaths still very high, this is not the time to give up the mask”. The United States is the country most bereaved by Covid-19 with more than 468,000 dead.