How to Choose the Best Cloth Face Mask for You A recent Northeastern University paper (PDF) reports that a surgical mask sealed to the wearer with a band cut from a pair of nylon stockings went from blocking out 50% to 75% of small particles (less than 0.3 micron) to blocking 90%. “The fit was already good,” said study co-author Loretta Fernandez, an associate professor of civil […]