The coronavirus, which has toppled world order, has also made quite a few things the new normal. Among those is the use of masks, which is one of the foremost defences that help slow the spread of the coronavirus (SARS-CoV-2) that causes COVID-19.
The multilayer mask layer recommendation is not new, but new research suggests that a three-layered mask is a safe option than single or double-layered clothing and are most effective at preventing aerosol generation.
The study is carried out by scientists in UC San Diego and the University of Toronto Engineering in collaboration with researchers at Bengaluru-based Indian Institute of Science (IISc). Their research suggests – when a person coughs, large droplets (greater than 200 microns) hit the inner surface of a mask at a high speed, these droplets penetrate the mask’s fabric and break up or ‘atomise’ into smaller droplets, resulting in a greater chance of aerosolisation and thereby carrying viruses with them.
The researchers noted that a single and double-layered mask did provide protection in blocking out some of the liquid volumes of the original droplets and are significantly better than wearing no mask at all. Their advice was also based on the studies that showed the three-layered mask prevented small particles from passing through its pores. The researchers have now indicated that three-layered surgical masks are also effective in stopping large droplets from a sneeze or cough from getting atomised into smaller droplets.
They used a droplet generator and high-speed cameras to closely track individual cough-like droplets containing virus emulating particles (VEPs) that get atomised when they hit a single-layer mask and several droplets pass through that layer. Similar experiments were carried out on double and multi-layered masks and they noted the size distribution of the resultant droplets generated after penetration through the mask’s fabric. Their study also mentioned that for single and double-layered masks, most of these atomised droplets were found to be smaller than 100 microns with the potential to become aerosols. These droplets can remain suspended in the air for a long time and potentially cause infection.
The researchers further clarified that when multi-layered masks are unavailable, even a single-layered mask can offer some protection, and they must be used wherever mandated by health officials.