Cloth masks ‘ugly’ as protection against COVID-19 and other viruses, study warns
WASHINGTON (StudyFinds.org) — Cloth masks are “ugly” when it comes to protecting people from COVID-19 and other airborne viruses, new research warns. Woven fabric does not sufficiently filter particles as well as masks like N95s, scientists say.
Like many other viruses, COVID-19 is transmitted primarily through airborne particles. An infected person exhales particles containing the virus into the air, which can then be inhaled by another person, who then becomes infected.
Face masks are widely considered an important first line of defense against airborne disease transmission, as confirmed by previous studies. Fueled by the omicron variant, the latest wave of the pandemic has prompted public health officials to recommend more protective face coverings because some masks offer significantly more protection than others.
For the new study, researchers from England, Germany and France examined the efficiency of particle filtration by a woven fabric, which, unlike the material used in standard air filters and face masks, consists of fibers twisted into threads.
Using state-of-the-art 3D images to see the airflow channels, the research team simulated the airflow through the channels and calculated the filtration efficiency for particles one micron and larger. diameter. The study, published in the journal Fluid physicsconcludes that for particles of this size range, the filtration efficiency is low.
“Masks are air filters and woven fabrics, like cotton, make good jeans, shirts and other clothes, but they are bad air filters. So use woven fabric for clothing and N95 or FFP2 or KF94 for masks,” study co-author Richard Sear, a computational physicist at the University of Surrey, says in a statement.
He explains that flow simulations suggest that when a person breathes through a fabric, most of the air flows through the spaces between the threads of the woven fabric, taking more than 90% of the particles with it.
“In other words, these relatively large deviations are responsible for fabric being a poor material for making air filters,” he continues. “In contrast, the filter layer of an N95 mask is made of much smaller five-micron fibers with 10 times smaller gaps, making it much better at filtering nasty particles from the air, like those containing virus.”
While previous research has found similar results, the study represents the first to simulate particles passing directly through the interstices of woven fabric.
Dr. Sear notes that good masks should have the “two Fs: good filtration and good fit. Surgical masks fit poorly, so a lot of unfiltered air passes past the edges of the mask through the cheeks and nose.
Stephen Beech, editor of the South West News Service, contributed to this report.