What material is most beneficial for homemade masks?
02 May, 2020
A team of researchers claims to have found the very best materials for homemade face masks: a combo of either cotton and chiffon or cotton and natural silk, both which may actually effectively filter droplets and aerosols.
The Centers for Disease Control and Prevention (CDC) have recently updated their guidelines on the use of face masks during the coronavirus disease 19 (COVID-19) pandemic.
The updated guidelines recommend wearing a cloth covering or a mask when it's difficult to keep physical distancing, such as for example when shopping.
But research into whether reusable cloth masks can slow the spread of the brand new coronavirus has led to contradictory findings.
For instance, some recent studies advise that reusable masks manufactured from cotton may be ineffective at filtering droplets containing the virus that triggers COVID-19: extreme acute respiratory syndrome coronavirus 2 (SARS-CoV-2).
Could other materials prove more effective? This can be the question that researchers - from the University of Chicago and the Argonne National Laboratory, both in Illinois - have aimed to answer in a fresh study.
Their findings, featured in the journal ACS Nano, suggest that one fabric combinations may go some way toward halting the spread of the brand new coronavirus.
How well the mask fits can be crucial
Within their study, the team experimented with various samples of cotton, chiffon, flannel, silk, spandex, satin, and polyester - by themselves and in combination.
They tested the fabric to see if it might filter tiny aerosol particles. This is due to researchers assume that SARS-CoV-2 may disseminate not simply through droplets - for example, from coughs - but also through minute particles that spread when people simply breathe, which are much harder to catch.
The team fanned particles measuring 10 nanometers to 6 micrometers in diameter over the various fabric samples at an airflow rate similar compared to that of a person’s breath when they are at rest.
The researchers discovered that a sheet of tightly woven cotton - of 600 threads per inch - plus two sheets of chiffon, made from polyester and spandex, seemed to maximize effective combination, filtering out 80-99% of the particles, according to their size.
The team even shows that the performance of this combination is comparable to that of N95 masks, which are used by healthcare professionals.
Other combinations that succeed, in line with the researchers, are tightly woven cotton plus natural silk or flannel, and cotton quilt with cotton-polyester batting.
The researchers make clear that combinations involving a fabric with a good weave, such as cotton, and the one which can take a static charge, such as for example silk, tend effective because they offer a double barrier: mechanical and electrostatic.
Yet they emphasize that for these masks to be truly effective, they must fit very snugly.
“The result of gaps between the contour of the face and the mask, as due to an improper fit, will affect the efficiency of any nose and mouth mask,” they write.
“Our findings indicate that leakages around the mask area can degrade efficiencies by [approximately] 50% or even more, pointing out the value of ‘fit’.”
- Abhiteja Konda et al.
Future studies, the researchers explain, should also pay attention to other potentially relevant factors, including the aftereffect of humidity on mask performance and whether reusing and washing homemade masks may reduce their effectiveness.
Source: www.medicalnewstoday.com