They're made of cotton. Or polyester. Or paper. Or polypropylene. Here's what researchers say about the effectiveness of the different types of face masks during this pandemic.
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A User's Guide To Masks: What's Best At Protecting Others (And Yourself)
Corrected: June 30, 2020 at 10:00 PM MDT
An earlier version of this story misspelled Supratik Guha's first name as Supatrik.
