Proper Double-Masking Raises COVID Protection
February 10, 2021 – Wearing a properly fitted surgical mask or doubling up on masks can significantly reduce the transmission of COVID-19 and slow the spread of new, more contagious strains, according to a CDC report released Wednesday.
Researchers have found that if two people wear surgical masks that are tied and tucked in flush with the face – or if both wear a cloth mask over a surgical mask – exposure to viral particles is reduced by more than 95%.
“The data in this report underscores the conclusion that a good fit can increase the overall effectiveness of the mask,” the authors wrote. “Several simple ways to improve the fit have been shown to be effective.”
A “simulated breathing experiment” shows surgical masks on their own block of 42% of the COVID-19 particles for the wearer, and cloth masks block about 44% of the particles. Wearing a cloth mask over a surgical mask increased the protection of the person wearing the masks, blocking 83% of small particles.
While other recent studies have looked at “mask adjusters” – a group who put on a mask to keep it snug to the face – and found that they improve performance, the CDC said it thought the best fit came from wearing a surgical mask covered by a cloth mask.
COVID deaths in the United States jumped in November and, although they are declining, remain high. Officials have warned that the UK-based variant could finally become the dominant strain in the US by March.
These findings emerge amid growing concerns over three new highly contagious COVID-19 variants first identified in the UK, South Africa and Brazil. All three have crossed American borders.
Regarding the new coronavirus variants, CDC director Rochelle Walensky, MD, told reporters during a White House briefing on Wednesday that the agency currently estimates that 1-4% of COVID cases in United States were caused by the British variant, also known as B117.
Regarding the mask study, Walensky said the science was already clear that mask requirements can reduce COVID-19 infections and deaths. But, she said, the CDC’s new research “highlights the importance of wearing a mask properly and making sure it fits tightly and snugly over the nose and mouth.”
Walensky said that any type of mask provides some protection, “and properly fitting masks have provided the best performance both in blocking emitted aerosols and in exposing aerosols to the receptor.”
While little is known about how to protect masks at the onset of the pandemic, growing research is clearly showing that they work well. A June article in the newspaper Fluid physics explained that a cough can cause droplets of 12 feet to travel in about 50 seconds. With a well-fitting, homemade cotton mask made up of multiple layers, these droplets only traveled about 2.5 inches.
An April study in Nature medicine found that surgical masks significantly reduced the transmission of cold and flu droplets. A January article in TheLancet Digital Health says an increase in the wearing of masks in a community would triple its likelihood of controlling the spread of COVID-19.
Finally, a CDC study released this month found that from March 22 to October 17, 2020, 10 sites in states with mask warrants reported a drop in the growth rates of COVID-19-related hospitalizations up to 5.5 percentage points. Currently, more than 40 states and territories have mask warrants.
To ensure proper mask wear, CDC recommendations include:
- Choose a mask with at least two layers of washable and breathable fabric
- Put the mask on your nose and mouth and secure it under your chin
- Tie the earrings of a surgical mask, where they attach to the mask, then tuck in and flatten the extra material near the face (knotted and folded masks)
- Adjust the mask against the sides of your face and slip the loops over your ears or tie the strings behind your head
- If you need to continually adjust your mask, it will not fit properly and you may need to find a different type or brand of mask.
- Wear your mask under your scarf, ski mask or balaclavain cold weather
- Keep a spare mask to replace the one that gets wet
- Store reusable wet masks in a plastic bag until they can be washed
Ken Terry, reporter for Medscape Medical News, contributed.
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