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The CDC is updating its mask guidance today to recommend new ways to make masks fit more tightly, including double-masking, knotting the ear loops or using a moldable nose wire. This is based on new science released today.
CDC researchers conducted an experiment in which they simulated aerosolized COVID-19 transmission between two people, and found that exposure was reduced by more than 95% when both people were wearing a cloth mask over a medical procedure mask.
"Masks work, and work best when they have a good fit and are worn correctly," says CDC director Dr. Rochelle Walensky.
The benefits are clear: In the CDC study, a medical procedure mask alone blocked 42% of particles from a simulated cough, while a cloth mask alone blocked 44%. A cloth mask covering a medical procedure mask blocked 92.5% of the cough particles.
And when both people were wearing fitted double masks, the receiver's exposure was reduced by 96%. When they were both wearing knotted and tucked masks, same thing -- 96% reduction.
from the CDC
Here is the new CDC mask guidance, based on this new research: https://www.cdc.gov/coronavirus/2019-ncov/your-health/effective-masks.html
interestingly, officials are asking that people not combine a KN95 mask with any other mask. they also ask that people not combine two disposable masks, as they are not designed to fit tightly and wearing them on top of each other will not improve the fit.
