How face masks work and which types offer the best COVID-19 protection

Breaking down different types of coverings, the proper way to take them on and off and how to tell if a mask is professional grade

Face masks are a simple way to help prevent the spread of the new coronavirus through talking, coughing or sneezing, scientists and public-health specialists say. But they need to be worn properly.

While some types of masks are more effective than others, public-health officials say any face covering — even a bandanna — is better than nothing.

Here’s how different types of masks stack up, and how they are meant to be used.


Cut from a different cloth

Common masks fall into three categories: cloth masks or coverings like gaiters, intended to prevent an infected person from spreading the virus by catching large droplets; surgical masks, with a more sophisticated design also meant to prevent the wearer from spreading diseases; and N95 masks, which protect the wearer as well, and fit tightly to the face.

There are three common types of masks that work differently and should be used differently: cloth, surgical and N95 masks. (iStock)


  • Typically homemade
  • Style and materials vary widely
  • Prevents wearer from spreading disease
  • Work in herd-immunity: the more wear masks, the more effective they are
  • Wash after use


  • Loose fit
  • Prevents wearer from spreading disease
  • Dispose after use
  • Made from a material called polypropylene


  • Tight fit, must be fit tested
  • Protects wearer if fitted properly
  • Limited quantity

(Source: Centers for Disease Control and Prevention)


Fit vs. function

A good cloth mask filters well and is comfortable to breathe through.

A cloth mask should consist of three layers: an inner layer near the mouth that can get moist, a middle filtration layer and an outer layer exposed to the outside environment. Here are the materials for homemade masks that do this best, according to the World Health Organization, using a scale that combines filter quality and breathability. A higher rating is better.

Breathability and filtration rating

  • Polypropylene: 16.9
  • Cotton (knit): 7.4
  • Polyester (knit): 6.8
  • Cellulose: 4.3

(Source: World Health Organization)

This photo taken on April 8, 2020 shows workers producing face masks that will be exported at a factory in Nanchang in China's central Jiangxi province. (Photo by STR/AFP via Getty Images)

How a mask fits is as important as what it is made of.

How to put on a mask

Surgical Mask

  • Check for defects in the face mask, such as tears or broken loops.
  • Place one loop over each ear. Mask will contour to face, but not as tightly as an N95.
  • Mask should sit on the bridge of the nose.


  • Straps rest at the back of your head. An N95 will contour tightly to face.
  • Mold metal strip to the shape of your nose.
  • Re-adjust straps or nosepiece until a proper seal is achieved.
  • Place both hands over the respirator and breathe. If there's leakage, there is not a proper seal.
  • If you can't get a proper seal, try a different N95 size or model

(Source: Centers for Disease Control and Prevention)

Removing a mask properly is also important to prevent the spread of the virus.

Three Steps to Removing an N95 Mask

Do not touch the front of the N95 to remove your mask. This can cause contamination.

Pull the straps from the back of your head. Discard while making sure to avoid touching the respirator.

This photo, taken on February 28, 2020, shows workers producing face masks at a factory in Handan in China's northern Hebei province. (Photo by STR/AFP via Getty Images)

Discard Your Mask and Wash Hands

If you need to re-use an N95 mask, store it in a paper bag for five days. Then you can re-use it.


Professional grade

N95 masks filter out at least 95% of very small particles when worn properly, including droplets carrying viruses. Versions with a plastic valve at the center, which makes the mask easier to exhale through, are intended for industrial workers and offer protection only to the wearer.

True N95s aren’t easy to wear properly. They must have a tight seal to the face to ensure that all air goes through the filter instead of around the edges. But they offer the best protection against the coronavirus, which is why the WHO recommends these masks be reserved for health-care workers.