COVID-19: Scientists test 14 face-coverings

Scientists at Duke University tested 14 different types of face-covering and found that one of them actually increases the risk of COVID-19 infection.

The coverings ranged from the kind worn by healthcare professionals to neck fleeces and DIY face coverings.

“The fundamental question is, how well does a specific mask type prevent droplets from spreading,” said lead researcher and molecular imaging specialist Martin Fischer.

Researchers of 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 a regular speech.

The result of their experiment shows that the least effective face-covering was a neck fleece. It was found to actually increase the risk of infection by having a droplet transmission fraction of 110%.

“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 added.

Bandannas, gaiters and knitted masks are also performed poorly in preventing the spread of the deadly coronavirus.

Fischer emphasized the need to really encourage everyone to wear masks that actually work. Hence, they did the study.

N95 masks, often used by health care professionals, worked best to stop the transmission of respiratory droplets during regular speech.

Other good performers at stopping leakage were three-layer surgical masks, and polypropylene mask.

Handmade cotton face coverings were also shown to perform well and eliminated a substantial amount of the spray from normal speech.

The study was published in Science Advances.

The league table of the 14 masks tested (picture number):

1st (most effective) N95 mask, no exhalation valve, fitted (14)
2nd Surgical mask (1)
3rd Cotton-polypropylene-cotton mask (5)
4th Two-layer polypropylene apron mask (4)
5th Two-layer cotton, pleated style mask (13)
6th Two-layer cotton, pleated style mask (7)
7th N95 mask with exhalation valve (2)
8th Two-layer cotton, Olston style mask (8)
9th One-layer Maxima AT mask (6)
10th One-layer cotton, pleated style mask (10)
11th Two-layer cotton, pleated style mask (9)
12th Knitted mask (3)
13th Bandana (12)
14th (least effective) Gaiter type neck fleece (11)