CATER Mask Decisions

December 1, 2020

Healththing Canada Compares Effectiveness of Mask

Porous Materials Provides Instruments to Analyze Nanofiber Non Wovens

Nonwovens Institute Receives Grant to Improve Properties of Mask Materials

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Healththing Canada Compares Effectiveness of Mask

Healthing.ca, is a destination for the straight facts on symptoms, diseases and treatments as well as smart takes on the latest health trends, research and the people who are disrupting health care as we know it. Laura Hensley is a writer with Healthing.ca. and has written an article showing that some masks are better than others.  McIlvaine comments are in italics.

A new study by the American Institute of Physics analyzed existing research on face masks and summarized their findings on which designs best filter or block out infectious coronavirus particles. Here’s what they found.

Only Certain Masks Block Aerosol Droplets

Not all masks are created equal, even though wearing a mask is much better than not wearing one at all. Masks range from homemade cloth ones, blue surgical masks, N95 respirators and store-bought three-layer woven designs. Experts advise Canadians wear three-layer masks.

If you’re going out into a crowded mall or grocery store, you want to sport a mask that offers both you and others as much protection as possible. How effective a mask is at blocking out infectious coronavirus particles depends on two things: the size of the particle and the design of the mask.

If someone who has the coronavirus talks, sneezes, coughs or even breathes, they expel infectious droplets that can spread the virus to other people. Large droplets are the most common, the study reported, but smaller droplets can become aerosolized and remain suspended in the air.

Non-medical cloth masks can reduce droplet spread, as they protect both the wearers and those around them. Only N95s block aerosols, the researchers wrote, because the masks filter out 95 per cent of particles.

Surgical masks, on the other hand, are fluid-resistant, and are designed to catch large respiratory droplets that are released when someone coughs or sneezes. These blue masks should cover the nose and mouth properly, but there is a chance of leakage around the mask’s edges during the inhaling and exhaling processes, the study reported.

“Such a dynamic leakage allows the direct contact of fluid droplets from the outside air to the wearer and vice versa,” researchers wrote, adding that surgical masks may not provide great protection against extremely fine aerosols or droplets.

Face Mask Breathability and Fabric

How comfortable a mask is depends on its fabric and design. Everyone knows how uncomfortable it can be to wear a mask made of scratchy fabric.

Researchers analyzed fabrics for their breathability. They found that masks made of hybrid polymer materials “could filter particles at high efficiency while simultaneously cooling the face.”

Furthermore, researchers looked at face mask fabric studies and found that materials including natural silk, chiffon weave (made of 90 per cent polyester and 10 per cent Spandex), and flannel provided “good electrostatic filtering of particles.”

Fabric with tighter weaves and low porosity, like cotton with a high thread count, offer better filtration. Bandanas and neck fleeces were not found to be very effective and “offered little protection against infection,” researchers wrote, based on their materials and designs. Because of the nature of fleece, it tends to break up larger particles into many little ones, according to previous research previous research out of Duke University in North Carolina.

Masks’ Role in Squashing the Pandemic

In case this needs to be hammered home again: masks help curb the spread of COVID-19. Health experts across Canada have continually stressed the importance of masks in public, indoor spaces and whenever physical distancing cannot be kept outside.

The American Institute of Physics researchers reviewed epidemiological studies that looked at whether face masks reduce the effective reproduction number (the transmission potential) of COVID-19. They used COVID-19 data from New York state and found that if the reproduction number drops below one, the pandemic stops spreading.

“The results suggest that the consistent use of efficient face masks, such as surgical masks, could lead to the eradication of the pandemic if at least 70 per cent of the residents use such masks in public consistently,” Sanjay Kumar, one of the study’s authors said in a statement.

“Even less efficient cloth masks could also slow the spread if worn consistently.”

This article is an example of the evolution of reporting which now shows the differences in mask performance. However, the big differences between  masks are not communicated here. McIlvaine will be contacting this group and offer free access to CATER Mask Decisions.

Porous Materials Provides Instruments to Analyze Nanofiber Non Wovens

Porous Materials Inc. (PMI), USA provides instruments to manufacture, test and analyze Pore characterization of Nanofiber Nonwoven and testing of Face Mask, Lab coats.

Nanofiber nonwovens are finding increasing applications in the filtration industry particularly in processes involving biotechnology. For such applications, pore volume is very important. Through pore diameter, pore throat diameter and permeability are also important pore structure characteristics. Nanofiber mats are normally sensitive to pressure and are often brittle. Therefore, the characterization technique should be such that the pore structure is not distorted. In this investigation, the applicability of the techniques, Mercury Intrusion Porosimetry, Liquid Extrusion Porosimetry and Liquid Extrusion Flow Porometry for pore structure characterization of nanofiber mats have been investigated. www.pmiapp.com

Nonwovens Institute Receives Grant to Improve Properties of Mask Materials

North Carolina State University’s Nonwovens Institute (NWI) received a six-month, approximately $400,000 grant from The National Institute for Innovation in Manufacturing Biopharmaceuticals (NIIMBL) to investigate improving the properties of materials they’re using for masks and respirators.

Ultimately, the researchers’ goal is to enhance the materials in order to boost performance and production capacity.

“The idea behind the grant is to improve the performance of the materials we are currently producing,” says Behnam Pourdeyhimi, executive director of NWI, Associate Dean and William A. Klopman Distinguished Professor and the project’s principle investigator.

N95 respirators and surgical masks are generally a sandwich of one or two common nonwoven layers – so-called “spunbond” layers that provide mask strength and protect the inner filtration layer – and a nonwoven meltblown material that filters microscopic unwanted particles like viruses and bacteria.

Because of the current critical need for masks caused by Covid-19, Pourdeyhimi and his NWI team created a new spunbond material that can serve as a filter without the need for a meltblown filtration layer. The unique fabric is composed of two different polymer materials that are combined to make a single fiber with significant strength and bulk, along with microfibers of a similar size to the normal meltblown filters. The new material has similar effectiveness to current filtration materials.

Since the start of the pandemic, NWI has been producing between 150,000 to 180,000 meters of this unique filter medium per week using its state-of the-art pilot facilities located at NC State’s Centennial Campus at the Center for Technology and Innovation.

To meet the demand for masks that can be worn by the general public, researchers are making single-layer masks out of the spunbond material. One of the objectives of the project funded by NIIMBL is to improve NWI’s spunbond material to meet the U.S. Food and Drug Administration (FDA) standards for surgical masks for particle filtration and fluid resistance.

“You want a mask that’s not too thick and too warm, and easy to breathe through,” Pourdeyhimi says. “What we want is a single layer that meets FDA requirements, and is not built on the meltblown filtration layer that is in short supply.”

NWI has also developed a new meltblown filtration media in its fight against Covid-19. Pourdeyhimi said his team is working around the clock five days per week to make the meltblown filtration material. NWI produces approximately 120,000 meters per week of the material.  

One of the objectives of the NIIMBL grant is to improve the meltblown material that goes into three-layer surgical masks as well as into N95 respirators, which are designed to filter more than 95% of airborne particles at 0.3 microns.

“Part of this grant is focused on reducing the weight of the filters without adversely impacting the performance of the filter – using less fabric would increase the available capacity,” Pourdeyhimi says.