CORONAVIRUS

Researchers Create Test To Determine Which Masks Are Least Effective

Aug 8, 2020, 7:32 PM
A variety of masks were tested for their effectiveness by researchers at Duke University. (Credit: ...
A variety of masks were tested for their effectiveness by researchers at Duke University. (Credit: Duke Health)
(Credit: Duke Health)

(CNN) — Schools are reopening, amusement parks are welcoming back visitors, and outdoor dining is the new way to eat out. But despite the signs that life is returning back to normal, the coronavirus pandemic has gone nowhere.

That’s why a group of researchers at Duke University created a simple technique to analyze the effectiveness of various types of masks which have become a critical component in stopping the spread of the virus.

The quest began when a professor at Duke’s School of Medicine was assisting a local group buy masks in bulk to distribute to community members in need. The professor wanted to make sure the group purchased masks that were actually effective.

In the study published Friday, researchers with Duke’s physics department demonstrated the use of a simple method that uses a laser beam and cell phone to evaluate the efficiency of masks by studying the transmission of respiratory droplets during regular speech.

“We use a black box, a laser, and a camera,” Martin Fischer, one of the authors of the study, told CNN. “The laser beam is expanded vertically to form a thin sheet of light, which we shine through slits on the left and right of the box.”

In the front of the box is a hole where a speaker can talk into it. A cell phone camera is placed on the back of the box to record light that is scattered in all directions by the respiratory droplets that cut through the laser beam when they talk.

A simple computer algorithm then counts the droplets seen in the video.

Encouraging the use of effective masks

Public health experts have spent months emphasizing that masks are one of the most effective tools to help fight the pandemic, and many US states have now introduced some kind of mask requirement.

But when testing their effectiveness, researchers discovered that some masks are quite literally useless.

Researchers tested 14 commonly available masks including a professionally fitted N95 mask, usually reserved for health care workers. First the test was performed with a speaker talking without wearing a mask. Then they did it again while a speaker was wearing a mask. Each mask was tested 10 times.

The most effective mask was the fitted N95. Three-layer surgical masks and cotton masks, which many people have been making at home, also performed well.

Neck fleeces, also called gaiter masks and often used by runners, were the least effective. In fact, wearing a fleece mask resulted in a higher number of respiratory droplets because the material seemed to break down larger droplets into smaller particles that are more easily carried away with air.

Folded bandanas and knitted masks also performed poorly and did not offer much protection.

“We were extremely surprised to find that the number of particles measured with the fleece actually exceeded the number of particles measured without wearing any mask,” Fischer said. “We want to emphasize that we really encourage people to wear masks, but we want them to wear masks that actually work.”

While the setup of the test is quite simple — all that is required is a box, a laser for less than $200, one lens, and a cell phone camera — Fischer does not recommend people to set them up at home.

Unless a person is familiar with laser safety or has optic experience, mishandling powerful lasers can cause permanent eye damage. However, the researchers are hoping companies, museums and community outreach centers will set up the test to show people which masks are the most effective.

“This is a very powerful visual tool to raise awareness that a very simple masks, like these homemade cotton masks, do really well to stop the majority of these respiratory droplets,” Fischer said. “Companies and manufacturers can set this up and test their mask designs before producing them, which would also be very useful.”

KSL 5 TV Live

Top Stories

Coronavirus

CHICAGO, ILLINOIS - SEPTEMBER 09: A pharmacist prepares to administer  COVID-19 vaccine booster sho...
Jed Boal

University Health recommends getting omicron booster and flu shot now

The CDC approved the COVID-19 bivalent boosters that target the most recent omicron variants on September 1. Since then, tens of thousands of Utahns have rolled up their sleeves.
6 days ago
FILE: Pfizer-BioNTech COVID-19 (left) and Moderna COVID-19 (right) vaccines are seen at a vaccinati...
Jed Boal

Despite reaching 5,000 deaths, Utah’s COVID-19 numbers are down

The director of the World Health Organization said yesterday about COVID-19, “the end is in sight,” even if we are not there yet.
17 days ago
FILE PHOTO (Photo by Al Bello/Getty Images)...
Associated Press

WHO: COVID end ‘in sight,’ deaths at lowest since March 2020

The head of the World Health Organization says the number of coronavirus deaths last week was the lowest reported number in the pandemic since March 2020, marking what could be a turning point in the years-long global outbreak.
17 days ago
A school classroom with chairs and desks...
Brooke Williams

Project to provide air purifiers in Utah K-12 classrooms

Cleaner air improves student performance, decreases COVID transmission and school absenteeism. New project provides air purifiers for classrooms in Utah.
18 days ago
SHANGHAI, CHINA - JULY 08: People walk by a closed store at a neighborhood designated as a medium-r...
Laura He, CNN Business

Zero- COVID-19 at what price? Chinese researchers are treading on sensitive ground

Authorities in Shanghai have denied a report by a leading Chinese real estate research firm that claimed more than a third of shops in a major mall had been shuttered because of strict COVID-19 curbs.
20 days ago
FILE: Pfizer-BioNTech COVID-19 (left) and Moderna COVID-19 (right) vaccines are seen at a vaccinati...
LAURA UNGAR AP Science Writer

Is COVID-19 winding down? Scientists say no

New booster shots have arrived and social distancing guidelines have eased but COVID-19 infections aren't going away anytime soon. Experts predict the scourge that's already lasted longer than the 1918 flu pandemic will linger far into the future as the virus continues to cause deaths and may well mutate or evolve into a new disease.
24 days ago

Sponsored Articles

Portrait of smiling practitioner with multi-ethnic senior people...
Summit Vista

How retirement communities help with healthy aging

There are many benefits that retirement communities contribute to healthy aging. Learn more about how it can enhance your life, or the life of your loved ones.
Happy diverse college or university students are having fun on their graduation day...
BYU MBA at the Marriott School of Business

How to choose what MBA program is right for you: Ask these questions before you apply!

Wondering what MBA program is right for you? Take this quiz before you apply to see if it will help you meet your goals.
Cloud storage technology with 3d rendering drawer with files in cloud...
PC Laptops

How backing up your computer can help you relieve stress

Don't wait for something bad to happen before backing up your computer. Learn how to protect your data before disaster strikes.
young woman with stickers on laptop computer...
Les Olson

7 ways print marketing materials can boost your business

Custom print marketing materials are a great way to leave an impression on clients or customers. Read for a few ideas to spread the word about your product or company.
young woman throwing clothes to organize a walk in closet...
Lighting Design

How to organize your walk-in closet | 7 easy tips to streamline your storage today

Read our tips to learn how to organize your walk-in closet for more storage space. These seven easy tips can help you get the most out of your space.
Types of Computer Malware and Examples...
PC Laptops

5 Nasty Types of Computer Malware and Examples | Everything You Need to Know to Keep Your Computer and Family Safe

Here are the different types of computer malware and examples that could potentially infect your computer.
Researchers Create Test To Determine Which Masks Are Least Effective