BENGALUR: Triple-layered masks, even those made of cloth, and N95 masks were found to provide the best protection from SARS-CoV-2, as they successfully prevent atomisation (or breaking down) of cough particles, finds a recent study. The researchers, however, clarify that when these masks are unavailable, even single-layered masks may offer some protection, and must be used wherever mandated.
A study by IISc researchers, in collaboration with scientists in UC San Diego and University of Toronto Engineering, found that the efficacy of face masks changes with the type of material, pore size and number of layers -- the most efficacious being the triple-layered masks, even those made of cloth.
Studies, by and large, have concentrated on leaks in the mask from the sides, that cause the virus to spread. However, these researchers tried to find out the role of the mask in atomising or breaking down cough droplets and causing the virus to spread.
In single- and double-layered masks, researchers found that droplets atomised to smaller than 100 microns, and had the potential to become aerosols. These suspended particles could remain in the air for a long time and cause infection. “You are protected, but others around you may not be,” explains Saptarshi Basu, Professor in the Department of Mechanical Engineering, in a release by the institute.
The experiment revealed that single-layered masks could only block 30 per cent of the initial droplet volume from escaping. Double-layered masks blocked 91 per cent, but more than a quarter of the atomised droplets generated were in the size range of aerosols. Meanwhile, triple-layered and N95 masks had zero or negligible droplet transmission and generation.