How do I pick the right mask?

Wearing a well-fitting mask effectively prevents the spread of COVID-19. 

The primary route of transmission of COVID-19 is from respiratory particles, which are expelled when breathing, talking, laughing, or coughing. Research shows that masks can protect the wearer by limiting the particles breathed inward, but can also protect others by reducing the outward spread of respiratory particles. While there are many masks to choose from, the CDC advises that all masks must be well-fitting, which means covering your nose and mouth and with no gaps around the sides of the face or nose. Here’s a breakdown of the current mask recommendations. 

Surgical masks are recommended for healthcare workers and the public, especially those at high risk, and can filter up to 85% of particles

Surgical masks are disposable, single-use masks with multiple layers. Although they may appear flimsy, the materials used are medical-grade and are very effective at protecting against COVID-19. However, they are also “one size fits some,” so you may need to make adjustments to improve the fit, for example by knotting the ear loops where they attach to the mask. 

Cloth masks are recommended for everyday use and can filter >70% of particles with the right fit and filtration. 

In a previous COVID-101 post, we describe ways to improve the fit, including choosing masks with embedded nose wire, adjustable ear straps, and that are snug on your cheeks and chin. For effective filtration, the WHO recommends looking for a cloth mask with three-layers. The outer layer should be a non-absorbent fabric like polyester; the middle layer should have filtration capacity, such as a non-woven spunbond polypropylene; and the inner layer should be tightly-woven cotton. Ways to have a better fit and extra protection with cloth and disposable masks include wearing two masks (disposable mask underneath and cloth mask on top).

N95 respirator masks are reserved for healthcare workers and can filter >95% of particles. When supplies are available, basic N95 and KN95 masks are offered to the public.

N95 and KN95 masks offer the greatest reduction in droplet spread compared to all other masks. While NIOSH-approved N95 respirators should be prioritized for medical professionals who work in extremely high transmission places, like a hospital, the CDC says respirators such as KN95s can be used in certain situations, including: 

  • Riding on planes, buses, trains, or other forms of public transportation, especially for long periods of time when in close contact with others.
  • Taking care of someone who is sick with COVID-19.
  • Working at a job where you interact with large numbers of the public.
  • If you are at increased risk for severe illness, for example, older adults or people with certain underlying medical conditions.
  • If you are immunocompromised or unvaccinated.

However, there are concerns about counterfeit KN95 masks, so you should take care to avoid purchasing these counterfeits.

Finally, well-fitting masks do not increase CO2 levels in the air you breathe. 

A mask should fit snugly on your face to prevent gaps through which larger respiratory droplets that may carry SARS-CoV-2 can escape. This does not mean that cloth or surgical masks are airtight. The CDC explains that CO2 molecules, which are very small compared to respiratory particles, can easily pass through the mask and therefore do not put you at risk. 

First posted: August 9, 2020

Last update: October 15, 2021 10:00 AM ET

Science review: JSS, ERS, GSN