When to avoid 'double masking,' according to the CDC

Earlier this month, the Centers for Disease Control and Prevention (CDC) updated its coronavirus face mask guidance to endorse "double masking" following the results of a lab experiment that concluded placing a cloth mask over a surgical mask, as well as using a properly fitted mask, was effective in stopping the spread of COVID-19. 

For the lab experiment, researchers, using simulated respiratory breaths, found that placing a cloth mask over a medical procedure mask or using a medical procedure mask with knotted ear loops and tucked in sides decreased exposure to potentially infectious aerosols by about 95%.

Despite the results, double masking may not be for everyone. In fact, the CDC on its website lists a couple of things to watch out for when "improving mask fit and filtration," which includes wearing two masks.

Two masks are better at stopping COVID-19 spread than one, CDC study finds

If breathing becomes too difficult, or your vision is obstructed, double masking might not be a good option for you. The CDC says to take the following into account when improving mask fit and filtration:

Breathing is not difficult

"Breathing might take more effort when wearing a mask that fits and filters better. For example, it might require more effort to breathe when wearing a ‘double mask,’" the CDC says. 

Vision is not obstructed

"Adding an extra layer or mask could block vision. Reduced vision could lead to trips, falls, or other injuries," per the federal agency. 

The CDC also advises to "try out any potential techniques for improved mask fit and filtration at home before trying it out in public."

"For example, try walking around the house or outside for several minutes while wearing a mask with improved fit and filtration to assure that you can breathe comfortably and that your vision is not reduced." 

Important to note: the agency advises against using two disposable masks, as they are "not designed to fit tightly and wearing more than one will not improve fit." It also does not advise combining a KN95 mask with any other mask. 

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In its recently updated guidance, the CDC also advises making sure the mask fits snugly against the face and picking a mask with layers to "keep your respiratory droplets in and others' out." 

Additionally, the CDC advises using a mask with a nose wire, using a mask fitter or brace to improve fit, and checking to ensure there are no gaps where air may flow. 

"The bottom line is this, masks work and they work best when they have a good fit and are worn correctly," CDC Director Dr. Rochelle Walensky said earlier this month when announcing the new guidance.