Wednesday, February 10, 2021, that found wearing a cloth mask over a surgical
mask offers more protection against the coronavirus, as does tying knots on the
ear loops of surgical masks.
For optimal protection, the CDC says to make sure the mask fits snugly against your
face and choose a mask with at least two layers.
In laboratory testing, researchers simulated coughs and breathing and tested how well
different masks worked to block aerosol particles. They compared wearing no mask, a
cloth mask, or a surgical mask. They also tested two methods to optimize the fit of cloth
and medical masks:
- Wearing a cloth mask over a surgical mask
- Tying knots on the ear loops of surgical mask and tucking in and flattening the extra material against the face.
Both methods produced substantially improved protection against transmission of and
exposure to infectious aerosols. In the study, wearing any type of mask performed
significantly better than not wearing a mask. Well fitting masks provided the greatest
performance at both blocking emitted aerosols and exposure of aerosols to the receiver.
In the breathing experiment, having both the source and the receiver wearing masks
modified to fit better reduce the receiver’s exposure by more than 95% compared to no
mask at all.
CDC Director Rochelle Walensky said that the laboratory findings underscore the
importance of wearing a mask correctly and ensuring it fits snugly over your nose and
mouth. The new information does not alter the CDC’s guidance on who should wear a
mask and when. The CDC’s guidance on improving mask fit now recommends as
- Choosing a mask with a nose wire which prevents air from leaking out along the top
- Using a mask fitter or brace over a disposable or cloth mask to prevent air from leaking out. These small reusable devices cinch a cloth or medical mask to create a tighter fit and improve mask performance.
- Make sure your mask fits snugly over your nose, mouth and chin.
- Add layers of material-either by using cloth mask with multiple layers of fabric or by wearing a disposable mask under a cloth mask.
- Double masking is not recommended with two disposable masks.
- Do not layer another mask on top of a KN95 mask. It should be used alone.
Please stay safe, maintain social distancing, wear a mask as suggested and get
vaccinated when it is available.
If you have any questions regarding mask use do not hesitate to call me at
Robert B. Gerber, DDS, FACD