(CNN) – New data from the U.S. Centers for Disease Control and Prevention (CDC) shows that wearing a double mask – a cloth mask over a medical mask, such as a blue disposable surgical mask – can significantly improve protection. The researchers found that the combination of the two masks can prevent 92.5% of potentially infectious particles from escaping by creating a tighter fit around the face.
The researchers also found that the overall performance of medical procedure masks can only be improved by folding the mask edges inward and tying the earmuff cords where they meet the mask material to reduce gaps. A knotted medical mask can block 63% of the aerosols that may contain coronavirus, a significant improvement from 42% if they are not knotted. The findings were published Wednesday in the CDC’s Morbidity and Mortality Weekly Report.
LOOK: does it help you with using two masks against the corona virus?
Since January 2021, the CDC has been evaluating dual mask and coupling methods to measure mask performance and protection. The researchers found that the effectiveness of fabrics and surgical masks can be improved by making sure they fit closely to the contours of the face to prevent air and particles from escaping from the openings around the edges of the mask.
The study found that when both a source of infection and an uninfected source were fitted with two masks, the exposure of the uninfected person to potentially infectious particles was reduced by 96.4%. When both people wore a tight-fitting, knotted mask only, the cumulative exposure of the uninfected person to potentially infectious particles was reduced by 95.9%. Both findings emphasize the importance of a good fit to maximize mask performance and reduce exposure.
“This observation suggests that arrangements that can be made to improve the fit may lead to improvements regardless of the baseline filtration efficiency of the masks,” the researchers wrote.
It’s unclear how or if the CDC will include these new findings in its mask recommendations.