Wearing a face mask helps prevent the spread of COVID-19 in two ways: It protects the person wearing a mask from being exposed to the virus and protects the people around them from being exposed to the virus.

When a person talks, coughs, sneezes, or even breathes, they are exposing the people around them to what is in their body through the spread of small drops of liquid, called respiratory droplets, and even smaller, drier particles that float in the air. These bigger droplets carry saliva, mucus, and other germs (like the disease that causes the COVID-19 virus) which fall to surfaces while the smaller particles tend to stay in the air for a period of time. When people inhale these droplets through their mouths, noses, or eyes or touch their face after touching a surface where droplets fell, they are exposing themselves to COVID-19 and other germs exhaled by people their area. Wearing a face mask can reduce the amount of those particles that are inhaled through the mouth and nose, and can help stop people from touching their faces. Research shows that masks help stop germs from getting out into common spaces while also reducing the amount of germs inhaled by masks wearers, which can help reduce the chances of more severe disease.

It is still important to note that though masks can be highly effective at preventing the spread of the virus, it also depends on the quality of the mask, the amount of layers it has, and how many people are wearing them in a specific area. This is why continuing to follow prevention protocols like social distancing and hand washing is still important. The U.S. Centers for Disease Control and Prevention now recommends fitting a cloth mask over a medical procedure mask, and knotting the ear loops of a medical procedure mask and then tucking in and flattening the extra material close to the face. However, the U.S. CDC does not recommend wearing two disposable masks at one time or another mask on top of a KN95 or N95 mask.

There have been several studies demonstrating that wearing a face mask could help protect both the person wearing the mask and the people around them from COVID-19. Additionally, the United States Centers for Disease Control & Prevention (U.S. CDC) updated their guidelines to reflect the two-way protection given by masks, and released a scientific brief on November 20, 2020 about how the community use of masks can help reduce the spread of COVID-19. An additional study from the group from February of 2021 showed that wearing any mask offers significantly more protection than not wearing a mask and showed protection rates of over 92% from aerosolized particles when lab dummies wore cloth masks over surgical masks.

While face mask requirements vary with every country and region, they have been shown to help protect both wearers and the community around them. The more layers of fabric, the better the protection they offer with higher thread counts and tighter weaves increasing their effectiveness.

As masks alone cannot stop COVID-19, the U.S. CDC continues to encourage people to socially distance themselves, wash their hands for 20 seconds, and avoid touching their face.