Home  |  News  |  Events  |  Contact  |  Publications  |  City of Cambridge

Face Masks

When To Wear a Mask Indoors     

  • If your mask makes you feel more comfortable, wear it!
  • If you are fully vaccinated, masks are optional in most settings. 
  • If you are NOT fully vaccinated, please continue to mask up to protect yourself and others.
  • Still need a vaccine? Visit the City of Cambridge's vaccine page

Some vaccinated friends, family, and co-workers will decide not to mask up, while others will prefer to keep wearing one. Fully vaccinated people who choose to wear masks may be immunocompromised or live with someone who is, they may have children who cannot yet be vaccinated, or they may simply be more comfortable doing so. 

The important thing is to be respectful of people’s choices.

Face Masks in Cambridge

People who are fully vaccinated are not required to wear face masks in Cambridge in most settings, in accordance with the May 2021 Massachusetts Department of Public Health advisory and Centers for Disease and Prevention (CDC) guidance. 

Residents are encouraged to follow the Massachusetts and CDC recommendations for vaccinated and unvaccinated people. Businesses are reminded that they may continue to require the use of face masks inside their establishments if they wish.

All people in Massachusetts (regardless of vaccination status) are required to wear face masks in certain settings, including transportation and health care facilities. Please see Covid-19 Mask Requirements in Massachusetts.

Choosing the Best Mask for You

If you or or a family member are unvaccinated or immunocompromised, remember that not all masks provide the same level of protection. New research shows that high quality “medical-style” masks available to the public are most effective at protecting the wearer from infection.

Look for masks that fit snugly and block at least 90% of small viral particles from being breathed in. Masks should also be comfortable, especially if they are being worn throughout the day. 


Wear a mask with excellent filtration. Aim for 90-95%.

  • Several types of disposable masks available to the public provide excellent personal protection. These “high filtration” masks include KF94 masks (made in Korea), KN95 masks (made in China) and flat medical-style masks that are quality-certified.
  • KN95 and KF94 fit more snugly, depending on face-shape, than flat medical-style masks. 
  • If shopping for masks, some keywords to look for are KF94, KN95, or ASTM-rated.
  • About Cloth Masks: Cloth masks are best suited to outdoor use when it's easy to social distance. Most cloth masks do a good job of protecting others if you are sick.

More information on pros and cons of different types of masks is available on the CDC website.


Choose masks that fit snugly and cover your nose, mouth, and chin.

  • All edges should touch your skin so that unfiltered air does not escape or enter through the gaps.
  • Try different shaped masks to fit your face.
  • Try "ear savers" or mask straps to change the way a mask fits on your face.
  • A bendable nose clip is important for keeping masks in place and closing gaps.
  • If you cannot get a good fit with a flat medical-style mask, consider placing a cloth mask over it. This is known as “double masking.”
  • See the CDC website for more tips on improving mask fit and double-masking
Mask Reuse and Care
  • High quality disposable masks can be reused many times, as long as they are not visibly damaged or soiled. In independent tests, these masks remained effective after 40 hours or more of use. 
  • Masks that have been filtering germs all day may have germs on their outside surface. When removing a mask, hold it by the ear loops and wash your hands afterwards.
  • Store used disposable masks in the open air or a paper bag to dry until you need them. 
  • Do not clean your disposable masks with soap or alcohol—or put them in the washing machine—because this will destroy their ability to block viral particles. Medical-style flat masks and KF94/KN95 masks still work when wet with perspiration. They can be dried with a tissue. 
  • Bacteria and fungi can grow on cloth masks, so they need to be washed daily with your laundry or in hot soapy water in the sink.
Updated: June 25, 2021


Cambridge Public Health Department
119 Windsor Street
Cambridge, MA 02139
617-665-3826 (main)
617-665-3800 (main)
617-665-3888 (fax)
617-643-0744 (TTY)

Hours: Monday-Friday:
8:30 a.m.–5 p.m.
After Hours

Map | Directory

Public Records 

Susan D. Breen
Interim Chief Public Health Officer



Cambirdge Health Alliance

Cambridge City
City of Cambridge