Researchers have tested 14 different types of facial coatings and found that one of them actually increases the risk of coronavirus infection.
Researchers at Duke University in North Carolina tested coatings ranging from the wear and tear of healthcare professionals to neck spots and knitted masks.
The authors of the study compared the spread of drops from a participant’s breath while wearing one of the cover materials to the results of a control study where their mouths were fully exposed.
The least effective facial coating in the study was one neck fleece which proved to increase the risk of infection by having a “droplet transfer fraction” of 110%.
Duke University researcher Martin Fischer, who put the test together, told CNN: “We were extremely surprised that the number of particles measured with fleece actually exceeded the number of particles measured without having a mask.
“We want to emphasize that we really encourage people to wear masks, but we want them to wear masks that actually work.”
ONE bandana was the second worst performing face coating but it did not increase the risk of infection, while a knitted cover every third worst.
The most effective face coating in the study was equipment N95 mask without valves having a droplet transmission fraction of 0.1%.
The healthcare coverage is used by healthcare workers in the front line.
ONE Surgical mask performed second best while a polypropylene mask came in third place.
Handmade cotton face coatings was also shown to work well and eliminated a significant amount of the spray from normal speech.
The study was published in the Journal of Science.
Mr Fischer said: “We confirmed that when people speak, small drops are banished, so that the disease can be spread by talking, without coughing or sneezing.
“We could also see that some face coatings worked much better than others when they blocked expelled particles.”
Eric Westman, one of the authors of the study, said: “Wearing a mask is a simple and easy way to reduce the spread of covid-19.
“About half of the infections come from people who do not show symptoms and often do not know they are infected. They can unknowingly spread the virus when they cough, sneeze and just talk.
“If everyone had a worm, we could stop up to 99% of these drops before they reach someone else.
“In the absence of a vaccine or antiviral drug, it is the proven way to protect others as well as yourself.”
The participants in the study wore one of the covers before speaking in the direction of a laser beam inside a black box.
Drops from the person’s breath then scatter light as they moved through the laser beam. This process was recorded using a mobile phone camera.
The study’s authors said that a “simple computer algorithm” was used to count the drops in the video.
League table of 14 tested masks (image number):
1st N95 mask, no exhalation valve, mounted (14)
2nd Surgical mask (1)
3rd Bomullspolypropylen-bollworm (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)
Eighth Two-layer cotton, Olston mask (8)
9th Single layer Maxima AT mask (6)
10th Single-layer cotton, pleated style mask (10)
11th Two-layer cotton, pleated style mask (9)
12th Knitted stitch (3)
13th Bandana (12)
14th Gaiter fleece of the Gaiter type (11)