Using items such as a box, laser and cell phone camera, scientists evaluated the most (and least) effective face mask models.
With just a box, a laser, a lens, and a cell phone camera, scientists at Duke University in the United States have developed a method to evaluate the effectiveness of face masks against the spread of Sars-CoV-2, the virus that causes Covid-19.
In a study published last week in the journal Science Advances, the team presented the simple, low-cost technique. “We confirmed that when people speak, small droplets get expelled, so disease can be spread by talking, without coughing or sneezing,” explained Martin Fischer, Ph.D., a chemist and physicist who was part of the team that developed the device, in a statement. “We could also see that some face coverings performed much better than others in blocking expelled particles.”
Among the types of face mask, the non-valved N95 – used mainly by health professionals in the front line of the Covid-19 pandemic – proved to be the most efficient. Standard surgical and polypropylene face masks also performed well.
Homemade cotton face masks also provided a good barrier against droplets expelled during speech. On the other hand, neck fleece and bandanas were ineffective. “If everyone wore a mask, we could stop up to 99% of these droplets before they reach someone else,” said Duke physician Eric Westman, co-author of the research.
The authors point out that further studies are needed to investigate variations in the protection of face masks during speech, in addition to other factors, such as how to wear the item properly. “But it demonstrates that this sort of test could easily be conducted by businesses and others that are providing masks to their employees or patrons,” Fischer said.
Approximately half of Covid-19 cases occur in asymptomatic people, who are unaware that they are infected. “They can unknowingly spread the virus when they cough, sneeze and just talk,” Westman said.
In the absence of a vaccine or a proven effective treatment, this is one of the only weapons we have available to protect ourselves against this disease.
Watch the experiments by Duke University scientists in the video below: