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Office of Environmental Health and Safety

February 15, 2021: Important Mask Use Update

Correct and consistent mask use is a critical step everyone can take to reduce their risk of getting and spreading COVID-19.  Masks work best when everyone wears them, but not all masks provide the same protection.  A common problem with some masks is if there are gaps between the mask and the wearer’s face, respiratory droplets containing the virus can leak in and out around the edges of the mask (on the top or the sides).  How well a mask fits, how well it filters the air, and how many layers it has are all important to consider when choosing which mask to wear.

First, everyone must keep in mind that social distancing remains the priority to prevent COVID-19 from spreading.

Ways to Increase Mask Protection

Improve fit to help prevent air (potentially with respiratory droplets containing the virus) from flowing freely around the edges of the mask and instead forcing air to flow through the mask.

Improve filtration to cause more respiratory droplets containing the virus to be captured by the mask.

Options to Improve Mask Fit

Nose Wires

Use cloth or medical procedure masks that have a nose wire (a metal strip along the top of the mask) to help prevent air leakage at the top of the mask. Nose wires can also help to prevent fogging of eyeglasses.  To get a good fit, make sure to bend the nose wire over your nose to conform to your face.

Knotting and Tucking

Knot the ear loops of a 3-ply face mask where they join the edge of the mask, then fold and tuck the unneeded material under the edges. This method is called “knotting and tucking” (for instructions, see: https://youtu.be/UANi8Cc71A0)

How to Check Mask Fit

  • Check for gaps by cupping your hands around the outside edges of the mask.  Make sure no air is flowing from the area near your eyes or from the sides of the mask.
  • If the mask has a good fit, you will feel warm air come through the front of the mask and may be able to see the mask material move in and out with each breath.
  • If glasses fog while wearing a mask, leakage around the mask is likely occurring.

Options to Improve Mask Filtration

Another important step to increase the protection offered by your mask is to improve filtration.  Masks capture respiratory droplets containing the virus when the wearer breathes out, blocking them from reaching the outside air and protecting others.  They also serve as a barrier to protect the wearer by capturing respiratory droplets containing the virus breathed out by others, so that the wearer does not breathe them in.  A mask with improved filtration will stop more respiratory droplets containing the virus from getting inside your mask if others are sick or escaping from your mask if you are sick.

Layering

Adding more layers of material to a mask (layering) is a good way to reduce the number of respiratory droplets containing the virus that come through the mask.  One layering strategy is to use a cloth mask that has multiple layers of fabric.  Another strategy is to wear two masks or a “double mask.”

Wearing Two Masks / “Double Masking”

Wearing a second mask on top of a first mask (to create a “double mask”) can:

  • Improve fit by pressing the inner mask closer to the face, thereby reducing the amount of air that leaks around the edges of the masks.
  • Improve filtration by adding more layers of material to reduce the number of respiratory droplets containing the virus that come through the masks.
  • If glasses fog while wearing a mask, leakage around the mask is likely occurring.

One way to do this is to wear a medical procedure mask underneath a cloth mask.  A recent study conducted in a laboratory found that this “double mask” combination provided much better protection to the wearer and to others as compared with a cloth mask by itself or a medical procedure mask by itself.

Please note there are some mask combinations that should not be used to “double mask.”

  • Do not combine two medical procedure masks to create a “double mask.”  Medical procedure masks are not designed to fit tightly and wearing a second medical procedure mask on top of the first medical procedure mask does not help to improve the fit.  
  • Do not combine a KN95 mask with any other masks.  You should only use one KN95 mask at a time, and you should not use any type of second mask on top of or underneath a KN95 mask.

Take into account the following considerations when improving mask fit and filtration:

  • Ensure 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.”
  • Ensure vision is not obstructed
    • Adding an extra layer or mask could block vision.  Reduced vision could lead to trips, falls, or other injuries

Always try 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.

Special considerations for children when using techniques for improved fit and filtration:

  • Children younger than 2 should not wear any masks.
  • Children 2 and older should always wear masks in a public setting or when they are around people who do not live with them.
  • Some children (age 2 and older) may tolerate wearing one mask without any problems but may not be able to tolerate improved fit and filtration techniques.

 

(Adapted from:  CDC)

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