Face mask material has a “notable impact” in stopping expelled respiratory droplets, one study recently found. Single-layer bandana-style masks offer the worst stopping-capability compared to other materials, researchers said.
The team from Florida Atlantic University explored the effectiveness of various materials in stopping propelled droplets through visualization experiments. Researchers used a manual pump and a mannequin to emulate coughs or sneezes.
Their findings were published on June 30 in Physics of Fluids.
The rationale behind face masks amid the coronavirus pandemic is to reduce the risk of cross-infection by respiratory droplets from infected to healthy individuals. Coughing, sneezing, talking and even breathing emits respiratory droplets that can land on healthy people and lead to illness via the respiratory tract.
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Researchers found that unobstructed, expelled droplets consistently traveled up to 12 feet, which is double the current social distancing guidelines. A large majority of droplets fell to the ground by this point, however.
Nevertheless, researchers advised updating the current social distancing guidelines.
Further, when the mannequin was fitted with a bandana, droplets traveled an average of 3 feet, 7 inches. Cotton folded handkerchiefs showed a bit more stopping-capability, with droplets traveling 1 feet, 3 inches.
For commercial masks, droplets traveled an average of 8 inches.
Most effective, however, were homemade stitched masks with multiple layers of quilting cotton. Droplets traveled about 2.5 inches on average.
Researchers said “leakage” likely remains an issue for people who rely on loosely-fitting masks. Also, even in the most effective face masks, some droplets make their way past small gaps along the edges.
They said the visuals in the study will help further convey the rationale behind adhering to face mask recommendations and social distancing guidelines.
