Some masks are more protective than others. But a new study didn’t show which ones work best.
Face masks play a critical role in helping to curb the spread of the novel coronavirus, and could save tens of thousands of lives in the U. S. if everyone wore them in public, experts have said. Yes, some face masks are more protective than others. But that doesn’t mean wearing neck gaiters — stretchy pieces of fabric that people, especially runners, pull up to cover their nose and mouth — is worse than wearing no masks at all, as some recent news articles have suggested. These news articles were based on a study published Aug.7 in the journal Science Advances, in which researchers tested a novel method for evaluating the effectiveness of face masks. In other words, it was a study conducted to test a methodology. However, the researchers did explore some mask effectiveness in a « proof-of-principle » test, to evaluate whether they could use this particular method to measure mask effectiveness. To do that, they had a handful of participants try out multiple types of masks. Related: Coronavirus live updates « The mask tests performed here… should serve only as a demonstration, » the authors wrote in the paper. « Inter-subject variations are to be expected, for example due to difference in physiology, mask fit, head position, speech pattern, and such. » In this setup, a person wears a face mask and speaks in the direction of a laser beam set up inside a box that’s expanded to be a sheet of light — and the droplets that come out of their mouths and through the masks scatter light, which is detected using a cellphone camera. A simple computer algorithm counts the droplets in the recorded video. The researchers demonstrated their method with 15 different face masks and face coverings; one participant tried out all the masks and four tried a subset of the masks. During each trial, the researchers had the participants say « stay healthy, people, » five times, and measured the number of droplets they emitted. The authors found that the number of droplets that escaped through the masks varied greatly. They did not see « any appreciable droplet » emission from the N95 respirator, for example, though those should typically be reserved for health care workers, co-author Martin Fischer, a chemist and physicist at Duke University in North Carolina, said at a news briefing today (Aug.
