University of British Columbia February 7, 2021
UBC research highlights the best styles and fabrics for COVID-19 masks.
A team of UBC researchers said that in the race to stop the spread of COVID-19, a fitted three-layer cloth mask can effectively filter COVID particles.
After testing several different mask styles and 41 fabrics, they found that masks composed of two layers of low-count quilted cotton and three layers of baby wipes were as effective as commercial non-surgical masks when stopped—and almost Just as breathable.
Cloth masks can filter out 80% of 3 micron particles and more than 90% of 10 micron particles.
"We focus on particles larger than 1 micron because these particles may be the most important for the spread of COVID-19," explains Dr. Steven Rogak, a professor of mechanical engineering who studies aerosols. "Although the size of the COVID-19 virus is only about 0.1 micrometers, it is always attached to larger objects, such as droplets from breathing, talking, and coughing. These droplets are usually in the micron rather than sub-micron range."
The World Health Organization guidelines recommend that non-medical masks be divided into three layers: an absorbent inner layer near the mouth, a middle filter layer, and an outer layer exposed to the external environment.
The team recommended specific fabrics for different parts of the mask: the outer layer is double-sided knitted cotton, quilted cotton, knitted nylon or polyester satin, and the nearest inner layer is double-sided knitted cotton, quilted cotton or plain silk to the skin. .
Nylon and polyester are waterproof to prevent harmful droplets from penetrating into the inner layer. Cotton and silk feel comfortable, have good air permeability, and absorb moisture and wick away sweat. Importantly, the fabric structure is important for air permeability and filtration efficiency. For example, fabrics such as polyester crepe (worsted polyester), high-count cotton and Dubin silk have poor air permeability.
Replaceable dry baby wipes are very good filters.
"Baby wipes are usually made of spunlace and spunbond polypropylene-similar to the type of polypropylene in medical masks and N95 respirators," said Jane Wang, PhD, a researcher and clinical professor in the medical school.
"They are breathable and can effectively capture particles. They are biocompatible and contain minimal preservatives and chemicals, otherwise they may cause irritation or breathing problems."
Steven Rogak. Credit: Steven Rogak
Researchers said that in addition to choosing highly efficient and breathable materials, a good seal around the mask is also very important.
"Even N95 masks will inhale large and large amounts of droplets containing a lot of viruses if they are not sealed. Compared with improperly installed N95 masks, well-fitted and well-designed cloth masks with baby wipes filters It will be more effective in filtering 5 or 10 micron particles," said Dr. Rogak.
He added that the leak rate is highest around the nose, chin and cheeks, and pleated masks tend to leak the most.
"The mask should not be flat on your mouth and nose, because it is less breathable, because actually only a small part of the fabric is exchanging air. Even if it is made of breathable material, it will not have that A feeling. You need to create an air pocket with a greater curvature in the front so that the entire mask can exchange air."
Dr. Wang said that in the final analysis, masking is an intervention aimed at reducing risk rather than eliminating it.
“In order for the intervention to be effective, people need to get the intervention and apply it correctly. If people wear the N95 mask on half of the face, it will not be effective. Masking will not be effective. The point should always be to wear the mask correctly by choosing a design that provides a good seal around the nose and mouth and avoids cross-contamination."
Reference: Steven N. Rogak, Timothy A. Sipkens, Mark Guan, Hamed Nikookar, Daniela Vargas Figueroa and Jing Wang, "Considering the characteristics of materials used for temporary masks", December 28, 2020, Aerosol Science and Technology. DOI: 10.1080/02786826.2020.1855321
This research was recently published in the journal Aerosol Science and Technology. An interactive version of the data and a simplified mask design tool are available at https://tsipkens.github.io/fmviz/
Dr. Wang continued to share information on the free mask project website, a grassroots initiative she took the lead.
The n95 mask is literally printed on the box with the words "do not prevent the new crown virus". Why? Because they know that masks don't work and don't want to be sued when you are sick.
N95 masks can only filter down to 0.3 microns. Covid is significantly smaller (eg .0125). Those masks didn't do anything damned except to make you look like an idiot.
If you really believe in science. You know that these masks didn't stop sh*t. Because real virologists have special clothes to deal with viruses like covid. Those whimsical *ss masks are not doing sh*t.
We just want to know how to wear a mask? ? We really need to pay the director of the National Institute of Allergy, more than half a million a year, and this is what we get...
The email address is optional. If provided, your email will not be published or shared.
SciTechDaily: The best home of science and technology news since 1998. Keep up to date with the latest technology news via email or social media.
A group of international scientists including researchers from the Australian National University (ANU) announced the largest number of gravitational waves ever detected. discover…
Copyright © 1998-2021 SciTechDaily. all rights reserved.