Evidence on Mask Fit

Five studies demonstrate that attention to fit can improve the overall filtration of the mask.

1. A peer-reviewed study on disposable masks, in which a mask with ties provided better filtration in an inward direction (i.e., protection of the wearer) than a similar mask on earloops. Experiments were conducted on one person.

2. A peer-reviewed study on disposable and cloth masks, in which a number of mask modifications each provided better filtration in an inward direction. Experiments were conducted on one person.

3. A peer-reviewed study on improving fit of cloth face covering with taping and with nylon hosiery. Experiments were conducted on manikins.

4. A CDC report showing that knotting the earloop very close to the mask and tucking in the fabric provides better filtration in both inward and outward directions. Experiments were conducted using manikins and disposable masks (see below for our thoughts on how to apply this to cloth masks). The same CDC report showed that wearing a cloth mask over a disposable mask provides better filtration in both inward and outward directions. Experiments were conducted using manikins.

5. A peer-reviewed study on improving the fit of medical and cloth masks using ‘hacks’ that improved fit. Hacks include increasing the tension of head attachments, eg, with earguards, and improving the seal at the edge of the mask, eg, by a mask brace. We have a page on different mask hacks and their performance.

Our practical advice on getting the best fit for cloth masks is here, and we have summaries on double-masking and mask hacks to improve fit.