Mask Guidance

Updated: November 17, 2021

The following information pertains to Yale University Mask Guidance. Please see Yale University’s Health Guidelines for more university requirements and information.

All individuals, regardless of vaccination status, are required to wear masks indoors while on campus except when an individual is alone in a segregated space, such as when working in a private office or seated in a partitioned cubicle. When you are in a segregated space, mask up if you have a visitor.

Students, faculty, staff, and postdoctoral/postgraduate trainees who have not been vaccinated or who have not submitted vaccination documentation to the university are required to wear masks outdoors on campus when 6-foot distancing cannot be maintained.


  • See below for options for instructors and lecturers.
  • All individuals are required to mask when using public or university transportation, including university shuttles.
  • Connecticut requires all individuals to mask in certain other settings at all times, including health care and child care facilities.
  • The university requires all individuals to mask in lecture halls and other classrooms at all times, without regard to vaccination status. Any student who is not wearing a mask in compliance with campus policy may be asked to leave the classroom.
  • In residential colleges, and other Yale housing, masking is not required when roommates are in their suites. Everyone should be masked when non-roommates are present, such as in an ensuite common room.
  • All individuals are expected to mask in dense social gatherings outdoors.
  • Contact tracers may ask close contacts to wear a mask indoors at all times.
  • Travelers returning from conferences and international travel may be asked to mask both indoors and outdoors while waiting for their upon-return test results.
  • Vendors, contractors, consultants, and suppliers must mask indoors at all times. They must mask outdoors if they cannot maintain 6-foot distancing. A mask is not required outdoors if 6-foot distancing can be maintained.

For more information, see Use and Care of Face Coverings. Of course, masks must be removed to eat and drink. Please be sure to minimize your time unmasked and follow Safe Campus Practices. Distancing and outdoor eating reduces your risk.

Options for Instructors and Lecturers

Faculty, instructors, and lecturers (including graduate student instructors of record) have several options for in-person teaching in an indoor classroom:

  • Regardless of vaccination status, wearing a mask and maintaining 6-foot distancing is our highest recommendation. While speech can transmit the virus, masks are very effective source control and distance reduces the exposure risk. A mask also protects the wearer. Acoustics engineers from Penn State University found that the disposable masks used at Yale are effective for teaching with minimal auditory distortion. Also, wearing a mask sets a good example.
  • Vaccinated instructors may choose to remove their masks as long as they maintain a 12-foot distance from all others in the classroom while unmasked. Unmasked instructors may not lecture for more than two hours or sing. We recommend using a microphone to avoid extended periods of unusually loud speech. (Contact EHS for special procedures for unmasked singing.) Guest lecturers (non-Yale affiliates) may not unmask, even if vaccinated.
  • Cloth face coverings with a clear panel are currently out of stock and may not be available for a month or more. While these masks show the wearer’s mouth, some are prone to fogging and auditory distortion. To be added to the waiting list, visit the YPPS site and click the “PPE Supply Replenishment” link. VPN required.
  • Face shields are plentiful and may be helpful to the deaf, hearing impaired, for language or vocal instruction, or for other instruction or activities where it is important for others to view the lower face. A face shield provides short-term proximity source control, but allows aerosols to escape and accumulate. Face shields may be used by fully vaccinated instructors with 12-foot distancing for up to two hours. Like a clear face mask, a face shield may be prone to fogging and auditory distortion. For more information, see Use and Care of Face Coverings. Face shields are available through the COVID Stockroom in SciQuest. Contact EHS for special procedures if proximity or extended use of a face shield is needed.
  • Shrouded face shields are offered for purchase through the COVID Stockroom in SciQuest. They are more expensive but provide better source control than a typical face shield.

While plexiglass is present in some classrooms, it does not materially prevent the accumulation or dispersal of aerosols in a room.

As a reminder, students are not permitted to remove their masks in the classroom.

Labs and Clinical Areas

Yale EHS has provided separate guidance for laboratories. Disposable 3-ply masks are provided to people working laboratories, as well as flame-resistant masks for those whose work involves pyrophoric materials. Double disposable masks, KN95s, and other cloth masks should not be worn in Yale laboratories.

Separate mask guidance has also been provided for clinical and other healthcare areas. Clinicians and staff in patient care areas are to only wear PPE provided by the facility. There is no need to double mask.

Contact if you have any questions.

CDC Mask Quality Guidance

Yale provides two masks to anyone working on campus: a 2-ply cloth face covering or a disposable 3-ply mask. These can be obtained through the YPPS ordering site. As explained below, a 3-ply ASTM-1 mask is also available via SciQuest. All of these masks meet the CDC guidelines. The 3-ply disposable and ASTM-1 masks both have nose wires, as recommended by the CDC.

The CDC’s guidance mentions the use of a mask fitter or brace to prevent leakage. Mask fitters and braces are not in common use and are not preferable to choosing a Yale-provided mask with the best fit for you. Remember that the best mask is a comfortable one that you can wear all day.

Why Face Coverings are Important

It is important to understand that face coverings provide a physical barrier that can help contain the spread of respiratory droplets when an infected person coughs, sneezes, or talks. This is considered source control. A face covering is not intended to fully protect the wearer, but by covering their mouth and nose with a face covering they are less likely to transmit the virus to others if they are asymptomatic or have unrecognized, early COVID-19 symptoms. Masks work best when everyone wears one. Throughout this pandemic, research has shown that the use of face coverings has reduced community transmission of COVID-19. A face covering also prevents the wearer from touching their nose and mouth with unwashed hands.

Factors to Consider When Selecting a Face Covering

The most important factors to consider when selecting a face covering are fit and comfort. A face covering should completely cover your nose and mouth, be secure under your chin and fit snugly against the sides of your face. It should be comfortable enough so you won’t fuss with it as you go about your day. Fit is the most important criteria to consider since a mask will only work if worn consistently. It must be easy to wear, and breathable.

In general, masks with layers can be more filtering than single layer masks and stop more respiratory droplets from getting through. The CDC recommends cloth masks with two or more layers of washable, breathable fabric that fit comfortably on the face. Yale’s cloth face coverings meet these criteria.

Double Masking

CDC guidance also suggests wearing a disposable mask underneath a cloth mask, so that the outer cloth mask pushes the edges of the inner mask against your face. A concurrent CDC study indicates that double masking can reduce a user’s exposure. In addition to increasing filtration, the outer cloth mask could also improve fit by helping secure the edges of the inner mask against the face. Double masking may improve fit for masks that have gaps and do not fit well.

Neither the CDC nor Yale is requiring the use of a double mask. Yale-provided masks provide very good protection, so using a double mask is optional. As mentioned above, it is not recommended to combine two disposable masks when double masking, since this will not improve fit.  Importantly, because breathability often decreases as filtration increases, do not wear masks or double up on masks if this feels suffocating or difficult to breathe.

  • Do not combine two disposable masks.
  • Do not wear masks with exhalation valves.
  • Do not wear cloth face coverings in the laboratory.
  • Do not wear masks made of a fabric that makes it difficult to breathe (e.g., vinyl).

If you choose to double mask, you may use the disposable 3-ply mask beneath the 2-ply cloth face covering—both available from Yale as described above (as noted above, double masking and cloth face coverings should not be worn in clinics and other healthcare areas).

Frequently Asked Questions

Do I need to wear a mask if I have been fully vaccinated?

Yes, as described above, effective August 2nd, 2021, all individuals, regardless of vaccination status are required to wear masks indoors while on campus except when an individual is alone in a segregated space, such as when working in a private office or seated in a partitioned cubicle.

As a federal contractor, Yale is obligated to follow CDC’s indoor masking recommendations, which are risk-based and related to community transmission. The CDC recommends universal indoor masking for counties with community transmission above 50 per 100,000 cases (“Substantial”) and above 100 per 100,000 cases (“High”). See:|Connecticut|9009|Risk|community_transmission_level

So, while COVID cases on campus are low, community transmission is much higher. Members of the Yale community regularly interact with others in the New Haven area. Indoor masking protects others by keeping campus cases low and reducing transmission between Yale and the New Haven community.

Do I need to wear a mask if I am using a standing desk in my cubicle?

In most cases, a mask will be required while standing at a standing desk in a partitioned office because your head will be close to or above the partition top. Contact your EHS Safety Advisor for an on-site evaluation if you have questions. Some desk/office arrangements may allow unmasking.

If I have been fully vaccinated, is it OK to wear a mask?

While not required in the certain circumstances described above, anyone who is fully vaccinated and would be more comfortable wearing a mask is welcome to do so. This public health measure may provide additional reassurance to individuals who feel they may be at greater risk, and also protects against other respiratory illnesses.

As an extra precaution, a fully vaccinated individual may wish to wear a mask for interactions with visitors, patients, or the general public, or if they are concerned that their immune system may be weakened (see below).

With the new variants of SARS-CoV-2 in circulation, should I get a better mask?

Yale provides all employees and students with a 2-ply cloth face covering or a 3-ply disposable mask. Both are effective in preventing transmission, including transmission of the new variants.

There is no evidence that protection from the new variants or more transmissible variants requires double-masking or a mask with better filtration.

I’m vaccinated, but my immune system may be weakened (e.g., due to illnesses or medication). What do you recommend?

According to CDC guidelines, if you have a condition or are taking medications that weaken your immune system, you may NOT be protected even if you are fully vaccinated. You should continue to wear a mask and take all precautions recommended for unvaccinated people until advised otherwise by your healthcare provider. Concerned individuals should consider the ASTM-1 surgical masks described below. These masks have very good filtration and fit. Please see CDC guidance for more information.

Should I double mask?

A recent CDC study found that double masking may be a way to increase filtration and improve the fit of face coverings. If you choose to double mask, be sure to wear the disposal mask under the cloth mask. Do not use two masks at a time if it makes breathing difficult—which is common during exertion. Many people find double masking to be uncomfortable.

Double masking should not be necessary if you are using one of the effective masks provided by Yale.

Is a better mask available?

Disposable ASTM-1 (rated) surgical masks are available via SciQuest from the “COVID-19 Stockroom at Yale” catalog. An ASTM mask is rated for medical use, has very good filtration, and fits better around the nose and cheeks for many people. These masks come in boxes marked “ASTM,” but otherwise look identical to the disposable 3-ply masks. Some people prefer an ASTM mask due to its better fit. These are the same masks that healthcare workers have used for routine protection since the pandemic’s start.

Can I get an N95 mask?

An N95 is actually a high-efficiency respirator that must fit tightly to work properly. Most people find wearing an N95 respirator for extended periods to be very uncomfortable. People looking for a better mask should purchase the disposable ASTM-1 (rated) surgical masks described above.

N95 respirators are not abundant, so Yale allocates these masks to researchers and healthcare workers who absolutely need them. (The CDC recommends these masks be reserved for healthcare workers.) These workers may order an N95 respirator from the “COVID-19 Stockroom at Yale” catalog in SciQuest. The Office of Environmental Health and Safety (EHS) will then reach out to gather information and schedule the training, fit-testing, and medical clearances required for people who need to wear an N95 respirator.

Yale provides some frontline workers an N95 respirator for use on a voluntary basis. If you have any questions regarding N95 respirators, please contact EHS at or 203-785-3550.

What about KN95 masks?

“KN95” is a Chinese designation for masks with good filtration. These typically have ear loops, which prevent a good fit for many people. When they do fit tightly, they filter well, but are difficult to breathe through for any length of time. (Do not use a KN95 if breathing is difficult.) A KN95 mask is not a substitute for an N95 respirator. While the FDA has given emergency use authorization for some brands if there is no alternative, there are many counterfeit and poor quality KN95 masks being sold. Since KN95 is not a U.S. standard, the use of hypoallergenic materials is not required and there is nothing preventing a manufacturer from using materials prone to allergies. We therefore generally do not recommend the acquisition of KN95 masks. People looking for a better mask should purchase the disposable ASTM-1 (rated) surgical masks described above.

A KN95 mask is not allowed in a clinical or healthcare setting, or YNHH space. Do not double mask if you are wearing a KN95.

Please write if you have questions.

What about KF94 and other masks?

A great variety of other masks are being advertised, but many are untested, non-standard and poor quality. We do not recommend their purchase or use.

How do I safely remove my mask?

Handle by the ties or ear loops only. Remove from your face and fold the outside corners together. Be careful not to touch your eyes, nose, and mouth when removing. Clean your hands after removing and store in a clean paper bag. Face masks can be generally worn for up to one week and disposed of when soiled or damaged.

My Yale cloth face covering is worn out, and all out of shape. Can I get a replacement?

New students arriving back at Yale for spring semester have been given a welcome kit that includes three cloth Yale cloth face coverings. Employees who have already received their original kit may purchase additional masks through the YPPS ordering site.

What should I do if the disposable 3-ply mask provided is too large for my face?

The University has obtained samples of smaller face masks that can be requested through the YPPS ordering site. The guidance also describes several strategies for improving the fit and function of your face covering including adding layers of material and knotting and tucking ear loops, as demonstrated in this video.

If concerns remain after trying the smaller face mask, please contact for additional options.

What options exist for the deaf and hard of hearing?

Yale offers two types of protection for the deaf and hard of hearing: clear face masks and face shields.

Clear face masks are available through the YPPS site by clicking the “PPE Supply Replenishment” link. (VPN is required.)

Face shields are available via the COVID stockroom in SciQuest.

Can I buy my own mask?

You are not required to use the masks provided by Yale, but your mask needs to meet the CDC mask criteria. Bandanas, scarfs, and gaiters are not allowed as a mask substitute at Yale.

In Summary

  • The 2-ply cloth face coverings and 3-ply disposable masks provided to employees and students are effective in preventing transmission, including transmission of the new variants. Disposable ASTM masks are another option, available via SciQuest. 
  • Workers who have additional questions about respiratory protection should contact EHS via 203-785-3550 or
  • Feel free to send any questions to