Face coverings made from cotton are likely better than synthetic face coverings for preventing the spread of the coronavirus, according to a new study published last week in journal ACS Nano, by the US National Institute of Standards and Technology (NIST).
Researchers examined 32 different cloth materials for effectiveness at blocking particles that cause COVID-19. Of the five most effective materials, three were 100 percent cotton and had visibly raised parts, such as on a flannel towel, according to a statement published on NIST’s website Monday.
Of the five least effective, four were synthetic – a term referring to fabrics that have been created, such as nylon or polyester, rather than natural, such as cotton.
None of the face coverings were close to the efficiency of the popular N95 mask, however.
“It turns out that off-the-shelf materials provide some protection from aerosols if you use multiple layers of cloth and a face covering fits snugly,” said Christopher Zangmeister, a researcher from NIST and member of the study, in the statement.
“But none are as good as an N95 mask,” he added.
The US Centers for Disease Control and Prevention (CDC) has been recommending since April that cloth masks should be worn in public settings where social distancing measures are hard to practice, like in grocery stores and pharmacies to curb the spread of COVID-19.
“CDC is additionally advising the use of simple cloth face coverings to slow the spread of the virus and help people who may have the virus and do not know it from transmitting it to others,” a statement from the time read.
The CDC also said that cloth face coverings can be fashioned from household items or made at home from common materials. Scrap fabric, a bandana, or an old t-shirt can be used to fashion a mask.
The new research suggests, however, that certain materials have more effectiveness than others.
While the team has likely the best material for a cloth mask, the usefulness of this data for individuals seeking to protect themselves may be limited. The best cloth masks in the study were also some of the hardest to breathe through, and would fail to meet health and safety standards, the statement read.
“The texture turned out to be one of the more useful parameters to look at because we found that most of the cotton fabrics with raised threads tended to filter best,” another researcher from NIST and member of the study Jamie Weaver said.
“Our findings suggest that a fabric’s ability to filter particles is based on a complex interplay between material type, fiber and weave structures, and yarn count,” he added.
The researchers urged caution in using the study’s findings however, noting that specially designed masks were still significantly better than anything tested.
“The bottom line is that none of these fabrics are as good as an N95 mask. Still, cloth face coverings can help slow the spread of coronavirus. We hope this research will help manufacturers and DIYers determine the best fabrics for the job and serve as a basis for additional research,” Zangmeister explains.