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An effective, well-fitted mask helps contain your respiratory droplets and particles—through which the virus spreads—and protects you from those spread by others. How well a masks works depends on both the material the mask is made of and how well it fits and seals to your face.
In general, you should wear a mask that:
Has two or more layers
Completely covers your nose and mouth
Fits snugly against the sides of your face and doesn’t have gaps
Has a nose wire (metal strip along the top of the mask that helps prevent air from leaking out)
N95 and KN95 Masks
Also called respirators, N95s and KN95s are designed for a very close facial fit. If they meet requirements and proper fit is achieved, both can capture and filter at least 95% of tiny particles or aerosols that carry the virus that causes coronavirus disease (COVID-19).
University of Maryland Medical System (UMMS) visitor restrictions and universal masking policy require every person entering one of our hospitals or physician practices to wear a face mask.
When COVID is highly prevalent in the community, our experts recommend that all individuals wear a well-fitting, high-quality mask such as a KN95 or N95 mask to protect themselves and everyone around them.
N95 masks meet U.S. standards, and KN95 masks are regulated by China. These masks have either ear loops that fit behind the ears or straps that go around the head. N95s and K95s can be worn for extended use and multiple times. They should be discarded and replaced if they are damaged, wet or soiled. They also should not be worn:
If you can’t breathe through them
If they have exhalation valves through which respiratory aerosols carrying COVID-19 can escape (masks with exhalation valves can be worn covered with a surgical mask)
The most widely available respirators that meet an international standard are KN95s, according to the CDC. But beware when shopping for these masks: About 60% of KN95 respirators in the United States are counterfeit (fake) and do not meet National Institute for Occupational Safety and Health (NIOSH) requirements. Look for KN95s that meet requirements similar to those set by NIOSH for respirators.
Surgical masks (also called disposable masks or medical procedure masks) are made of a combination of paper and plastics.
When worn properly, surgical masks help block large droplets, splashes and sprays or splatter that may contain germs. However, surgical masks are not highly effective at blocking out tiny particles in the air — “aerosols” that are generated by breathing, talking, coughing, or sneezing and are the primary mode of transmission of the germ (virus) that causes COVID-19.
Because of the loose fit between the surface of the mask and your face, they do not provide complete protection from the COVID-19 virus.
Choose surgical masks with:
A proper fit over your nose and mouth (to prevent leaks)
Multiple layers of non-woven material
A nose wire
You can wear a surgical mask underneath a cloth mask for improved fit and filtration. However, you should not wear a surgical mask underneath another medical procedure mask. A mask fitter or brace can also improve the fit of your surgical mask.
Do not wear surgical masks that are wet or dirty. If your surgical mask is damaged or soiled, or if you have trouble breathing through the mask, you should remove and safely discard it and then put on a new mask.
Cloth masks can be made from a variety of fabrics. Many types of cloth masks are widely available. In general, cloth masks are unlikely to provide adequate protection against the highly transmissible Omicron variant of COVID-19, and are not recommended as a primary strategy.
If you prefer to wear a cloth mask for comfort, then you should wear one that:
Has multiple layers of tightly woven, breathable fabric
Fits properly over your nose and mouth
Has a nose wire
Has the ability to insert a filter
Avoid cloth masks with:
Gaps around the sides of the face or nose
Exhalation valves, vents or other openings through which droplets can escape
Single-layer fabric or thin fabric that doesn’t block light
Depending on how they fit and how they are made, cloth masks vary in how well they can protect you and others from getting and spreading COVID-19. Remember, you can wear a cloth mask on top of a surgical mask for improved fit and filtration. You can also combine your cloth mask with a mask fitter or brace to help improve fit.
The CDC does not recommend the use of face shields as substitutes for face masks for protection against COVID-19.
Face shields are not effective at protecting you and others from respiratory droplets. They have large gaps below and alongside the face through which droplets can escape and reach others around you.