Types of Masks and Respirators, January 14, 2022

"Summary of Recent Changes

• Added information to present similar content for masks and respirators
• Clarified that people can choose respirators such as N95s and KN95s, including removing concerns related to supply shortages for N95s
• Clarified that “surgical N95s” are a specific type of respirator that should be reserved for healthcare settings
• Clarified that some types of masks and respirators provide more protection to the wearer than others

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Key Messages:

• Masking is a critical public health tool for preventing spread of COVID-19, and it is important to remember that any mask is better than no mask.
• To protect yourself and others from COVID-19, CDC continues to recommend that you wear the most protective mask you can that fits well and that you will wear consistently.
• Masks and respirators are effective at reducing transmission of SARS-CoV-2, the virus that causes COVID-19, when worn consistently and correctly.
• Some masks and respirators offer higher levels of protection than others, and some may be harder to tolerate or wear consistently than others. It is most important to wear a well-fitted mask or respirator correctly that is comfortable for you and that provides good protection.
• While all masks and respirators provide some level of protection, properly fitted respirators provide the highest level of protection. Wearing a highly protective mask or respirator may be most important for certain higher risk situations, or by some people at increased risk for severe disease.
• CDC’s mask recommendations provide information that people can use to improve how well their masks protect them.

This page describes different types of masks and respirators that you can use to protect yourself and others from getting and spreading COVID-19. Masks and respirators can provide varying degrees of protection, with well-fitting National Institute for Occupational Safety and Health (NIOSH)-approved respirators offering the most protection. Masking is a critical public health tool for preventing spread of COVID-19, and it is important to remember that any mask is better than no mask.  This page presents options in order of least to most protective. To protect yourself and others from COVID-19, CDC continues to recommend that you wear the most protective mask you can that fits well and that you will wear consistently.

Types of Masks and Respirators

Masks are made to contain droplets and particles you breathe, cough, or sneeze out. If they fit closely to the face, they can also provide you some protection from particles spread by others, including the virus that causes COVID-19.

Respirators are made to protect you by filtering the air and fitting closely on the face to filter out particles, including the virus that causes COVID-19. They can also contain droplets and particles you breathe, cough, or sneeze out so you do not spread them to others.

Choosing a Mask or Respirator for Different Situations

Masks and respirators (i.e., specialized filtering masks such as “N95s”) can provide different levels of protection depending on the type of mask and how they are used. Loosely woven cloth products provide the least protection, layered finely woven products offer more protection, well-fitting disposable surgical masks and KN95s offer even more protection, and well-fitting NIOSH-approved respirators (including N95s) offer the highest level of protection.

Whatever product you choose, it should provide a good fit (i.e., fitting closely on the face without any gaps along the edges or around the nose) and be comfortable enough when worn properly (covering your nose and mouth) so that you can keep it on when you need to. Learn how to improve how well your mask protects you by visiting CDC’s Improve How Your Mask Protects You page.

A respirator has better filtration, and if worn properly the whole time it is in use, can provide a higher level of protection than a cloth or procedural mask. A mask or respirator will be less effective if it fits poorly or if you wear it improperly or take it off frequently. A respirator may be considered in certain situations and by certain people when greater protection is needed or desired.

• When caring for someone who is sick with COVID-19.
• If you are at increased risk for severe illness, for example, people who are immunocompromised, older adults, and people with certain underlying medical conditions.
• When working at a job where you interact with large numbers of the public, especially when not everyone is consistently wearing a mask. For example, bus drivers and grocery store workers.
• When riding on planes, buses, trains, or other forms of public transportation*, especially if it is for a long period of time on crowded conveyances.
• When physical distancing is not possible or when you are in crowded indoor or outdoor public settings.
• If you are not up to date on COVID-19 vaccinations.

*Note: The options listed on this page may be used to fulfill the requirements of CDC’s Mask Order for public transportation. Learn more about attributes of masks needed to fulfill the requirements of the Order at this website.

Masks

When choosing a mask, look at how well it fits. Gaps can let air with respiratory droplets leak in and out around the edges of the mask. Gaps can be caused by choosing the wrong size or type of mask and when a mask is worn with facial hair.

It is important to check that it fits snugly over your nose, mouth, and chin.

• 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.

Cloth Masks

Cloth Masks can be made from a variety of fabrics and many types of cloth masks are available.

Wear cloth masks with

• A proper fit over your nose, mouth, and chin to prevent leaks
• Multiple layers of tightly woven, breathable fabric
• Nose wire
• Fabric that blocks light when held up to bright light source

Do NOT wear cloth masks with

• Gaps around the sides of the face or nose
• Exhalation valves, vents, or other openings (see example)
• Single-layer fabric or those made of thin fabric that don’t block light
• Wet or dirty material.
  
  

  Procedure Masks

  Disposable procedure masks are widely available. They are sometimes referred to as surgical masks or medical procedure masks.

  Wear procedure masks with

  • A proper fit over your nose, mouth, and chin to prevent leaks
  • Multiple layers of non-woven material
  • A nose wire

  

  Do NOT wear procedure masks with

  • Gaps around the sides of the face or nose (see example)
  • Wet or dirty material.."
    Face masks 

Association of State-Issued Mask Mandates and Allowing On-Premises Restaurant Dining with County-Level COVID-19 Case and Death Growth Rates — United States, March 1–December 31, 2020

"Summary

What is already known about this topic?

Universal masking and avoiding nonessential indoor spaces are recommended to mitigate the spread of COVID-19.

What is added by this report?

Mandating masks was associated with a decrease in daily COVID-19 case and death growth rates within 20 days of implementation. Allowing on-premises restaurant dining was associated with an increase in daily COVID-19 case growth rates 41–100 days after implementation and an increase in daily death growth rates 61–100 days after implementation.

What are the implications for public health practice?

Mask mandates and restricting any on-premises dining at restaurants can help limit community transmission of COVID-19 and reduce case and death growth rates. These findings can inform public policies to reduce community spread of COVID-19..."
State-Issued Mask Mandates 

Scientific Brief: Community Use of Cloth Masks to Control the Spread of SARS-CoV-2

"Background

SARS-CoV-2 infection is transmitted predominately by respiratory droplets generated when people cough, sneeze, sing, talk, or breathe. CDC recommends community use of masks, specifically non-valved multi-layer cloth masks, to prevent transmission of SARS-CoV-2. Masks are primarily intended to reduce the emission of virus-laden droplets (“source control”), which is especially relevant for asymptomatic or presymptomatic infected wearers who feel well and may be unaware of their infectiousness to others, and who are estimated to account for more than 50% of transmissions.^1,2  Masks also help reduce inhalation of these droplets by the wearer (“filtration for personal protection”). The community benefit of masking for SARS-CoV-2 control is due to the combination of these effects; individual prevention benefit increases with increasing numbers of people using masks consistently and correctly.

Source Control to Block Exhaled Virus

Multi-layer cloth masks block release of exhaled respiratory particles into the environment,^3-6 along with the microorganisms these particles carry.^7,8  Cloth masks not only effectively block most large droplets (i.e., 20-30 microns and larger)⁹ but they can also block the exhalation of fine droplets and particles (also often referred to as aerosols) smaller than 10 microns ;^3,5 which increase in number with the volume of speech^10-12 and specific types of phonation.¹³ Multi-layer cloth masks can both block up to 50-70% of these fine droplets and particles^3,14  and limit the forward spread of those that are not captured.^5,6,15,16 Upwards of 80% blockage has been achieved in human experiments that have measured blocking of all respiratory droplets,⁴ with cloth masks in some studies performing on par with surgical masks as barriers for source control.^3,9,14

Filtration for Personal Protection

Studies demonstrate that cloth mask materials can also reduce wearers’ exposure to infectious droplets through filtration, including filtration of fine droplets and particles less than 10 microns. The relative filtration effectiveness of various masks has varied widely across studies, in large part due to variation in experimental design and particle sizes analyzed. Multiple layers of cloth with higher thread counts have demonstrated superior performance compared to single layers of cloth with lower thread counts, in some cases filtering nearly 50% of fine particles less than 1 micron .^14,17-29 Some materials (e.g., polypropylene) may enhance filtering effectiveness by generating triboelectric charge (a form of static electricity) that enhances capture of charged particles^18,30 while others (e.g., silk) may help repel moist droplets³¹ and reduce fabric wetting and thus maintain breathability and comfort.

Human Studies of Masking and SARS-CoV-2 Transmission

Data regarding the “real-world” effectiveness of community masking are limited to observational and epidemiological studies.

• An investigation of a high-exposure event, in which 2 symptomatically ill hair stylists interacted for an average of 15 minutes with each of 139 clients during an 8-day period, found that none of the 67 clients who subsequently consented to an interview and testing developed infection. The stylists and all clients universally wore masks in the salon as required by local ordinance and company policy at the time.³²
• In a study of 124 Beijing households with > 1 laboratory-confirmed case of SARS-CoV-2 infection, mask use by the index patient and family contacts before the index patient developed symptoms reduced secondary transmission within the households by 79%.³³
• A retrospective case-control study from Thailand documented that, among more than 1,000 persons interviewed as part of contact tracing investigations, those who reported having always worn a mask during high-risk exposures experienced a greater than 70% reduced risk of acquiring infection compared with persons who did not wear masks under these circumstances.³⁴
• A study of an outbreak aboard the USS Theodore Roosevelt, an environment notable for congregate living quarters and close working environments, found that use of face coverings on-board was associated with a 70% reduced risk.³⁵
• Investigations involving infected passengers aboard flights longer than 10 hours strongly suggest that masking prevented in-flight transmissions, as demonstrated by the absence of infection developing in other passengers and crew in the 14 days following exposure.^...
  Cloth masks