While some masks can be as protective as standard surgical masks against COVID-19, new research suggests that one type could be making things worse.
Neck fleeces, in particular, may even be worse than wearing no mask at all, according to researchers at Duke University.
"We noticed that speaking through some masks (particularly the neck fleece) seemed to disperse the largest droplets into a multitude of smaller droplets, which explains the apparent increase in droplet count relative to no mask in that case," the researchers wrote in a recently published study in Science Advances.
Since smaller particles are airborne for a longer period of time than larger droplets, which sink faster, "the use of such a mask might be counterproductive," researchers said.
Likewise, the study indicated that bandanas "didn’t block the droplets much at all."
The researchers at Duke provided a visual study to prove that face masks are effective in reducing droplet transmissions. After testing 14 commonly available masks or masks alternatives, researchers found that not all masks were effective tools against spreading the virus.
"We confirmed that when people speak, small droplets get expelled, so disease can be spread by talking, without coughing or sneezing,” one of the study’s co-authors, Dr. Martin Fischer, said. “We could also see that some face coverings performed much better than others in blocking expelled particles.”
Researchers noted that the best face coverings were N95 masks without valves -- which are used by front-line health care workers -- although surgical or polypropylene masks also performed well.
Hand-made cotton face coverings also "provided good coverage" and eliminated a "substantial amount" of the spray from when someone speaks.
“Wearing a mask is a simple and easy way to reduce the spread of COVID-19,” co-author and Duke physician Dr. Eric Westman said. “About half of infections are from people who don’t show symptoms, and often don’t know they’re infected. They can unknowingly spread the virus when the cough, sneeze and just talk."
In doing so, Westman said people could eliminate up to 99% of droplets before they reach someone else.
“In the absence of a vaccine or antiviral medicine, it’s the one proven way to protect others as well as yourself," he added.
In July, the Centers for Disease Control and Prevention director Dr. Robert Redfield noted that while "we are not defenseless against COVID-19, the use of cloth face coverings is "one of the most powerful weapons we have to slow and stop the spread of the virus – particularly when used universally within a community setting."