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Researchers Create New Test to Find Which Face Masks Are The Least Effective




  • Researchers from Duke University created a new way to test the effectivity of face masks.
  • By using a simple setup, they figured out which mask is least effective against respiratory droplets.
  • One of the researchers, Martin Fischer, said companies and manufacturers may want to do this test before releasing their products in the market.
  • However, he cautioned individuals and non-experts from trying it out at home because it could pose unknown dangers.

Despite the emergence of the “new normal” in schools and other industries, it seems that the treatment and control for COVID-19 has gone on a standstill. This is why a group of researchers at Duke University has created a new technique to test various types of face masks and its effectivity in stopping the spread of the virus.

Health experts and government officials have been advocating the use of face masks for months, emphasizing the protection it provides against the virus. It has become a requirement in the “new normal” as the cases of COVID-19 victims continue to rise.


Some have previously questioned how masks could help, but since most governments mandated its citizens to use masks, the issue had seemingly died down.

The experiment

This new test started when a professor at Duke’s School of Medicine assisted a local group in bulk-buying face masks for their community members in need. The professor, according to reports, claimed that he wanted to make sure the face masks were actually working.

The study had researchers from Duke’s physics department using a laser beam and a cellphone to evaluate how the masks work against respiratory droplets released when a person speaks. The test was performed in two parts: one with the speaker without a mask, and then while a speaker was wearing a mask.


The experiment used a black box, a $200-laser beam, and cameras to capture respiratory droplets.

Martin Fischer, one of the authors of the study, shared that they used a laser beam to form a thin sheet of light directed towards the slits on the left and right of the box, while a speaker talks into a hole in the front. 

A cellphone camera is also placed on the box to record the light that is scattered after the laser beam cuts through the respiratory droplets released when they talk. These droplets are counted using a simple computer algorithm, as seen in the video.

Testing the different face masks

Researchers tested 14 different masks, including the professionally fitted N95 mask which is typically reserved for health care workers. Each mask was tested 10 times. 


During the experimental testing, researchers discovered that some masks are quite useless. The experiment, however, proved that out of the 14 masks, the fitted N95 was most effective, followed by the three-layer surgical masks, and cotton masks.

mask test

Folded bandanas and knitted masks did not seem to offer much protection, but neck fleeces (gaiter masks) typically used by runners, were the least effective. In fact, the test showed that fleece breaks down the water droplets further, resulting in a higher number of respiratory droplets that are more easily carried away with air.


“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.”

Hope for the future

While the experiment proved to be enlightening despite its apparent simplicity, Fischer does not recommend setting them up at home unless the person is familiar with laser safety. However, Fischer, along with the other researchers hoped that companies, museums, and community outreach centers will set up a similar test to prove which masks are the most effective.

“This is a very powerful visual tool to raise awareness that 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.”

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