Wear a mask

When you’re indoors or in a crowded place, a mask gives you and everyone extra protection

Everyone must wear a mask when inside public buildings

No matter your vaccine status, you must wear a mask inside all public buildings. This includes places like stores and restaurants (when not actively eating or drinking), and at large indoor events.

You must wear a mask at all businesses and venues, as well as when you are:

  • Seeking healthcare (including any waiting rooms)
  • Inside a K-to-12 school, childcare facility, youth sports, or other youth setting 
  • Inside homeless shelters, cooling centers, and emergency shelters
  • At long-term care facilities and adult and senior care centers
  • Inside a jail

This update to San Francisco’s masking health order is in effect through January 31, 2022.


You must also wear a mask when you are:

  • On public transportation (or waiting for it indoors)
  • Driving or riding in a taxi or rideshare vehicle (even by yourself)

Scarves, ski masks, balaclavas, or bandanas are not allowed on any public transportation (or while waiting for it). This is by CDC order. See SF guidance on traveling on public transit.

Certain groups are not required to wear a mask


Children under 2 years old must not wear masks. They might suffocate.

Children 2 and older must wear masks inside public buildings. This includes in-person schoolyouth programs, and childcare programs as well as youth sports. However, businesses should not refuse an essential service, like groceries, to someone because a child is not wearing a face covering or not wearing it properly.

Those with certain health and safety needs

You do not have to wear a mask if:

  • You have a physical, intellectual, or developmental disability that keeps you from wearing a mask.
  • You have a letter from a medical professional saying you do not need to wear one because of your condition. The document does not need to explain your medical condition. The documentation should include the contact and license information of the medical professional.
  • You will create a safety hazard at work (under established health and safety guidelines) by wearing anything on your face while at work.

You should not wear a mask if:

  • You have trouble breathing or are not able to take off your mask without help.
  • You’re deaf and use facial and mouth movements as part of communication. You should remove your mask while communicating.

If for some other reason you can’t wear a medical or fabric mask, you must still wear something over your nose and mouth, such as a gaiter in 2 layers.

The best mask is one that fits well and has good filtration

A well-fitting mask has no gaps between the face and mask, such as above the nose or at the sides. Good filtration blocks the virus particles from going through the mask itself. You can get good filtration with the right materials and by using more layers.

Double masking

Double masking is an effective way to improve fit and filtration. A close-fitting cloth mask can be worn on top of a surgical/disposable mask to improve the seal of the mask to the face.

Cloth masks

Cloth masks can work well only if they are tight fitting and made of materials that filter out small particles. Good cloth masks have:

  • Two layers of tightly woven cotton with a third layer of non-woven fabric
  • The third layer could be a mask filter insert, or a synthetic fabric such as polypropylene
  • Nose wires to reduce gaps from the nose
  • Adjustable ear loops or straps that go around the head to reduce gaps from the face.

Medical masks (surgical or disposable face masks)

Medical masks are often loose fitting. You can improve the fit in different ways such as using a mask fitter or brace. Look for masks that have:

  • 3 layers
  • An adjustable nose wire
  • Ties instead of ear loops as they may improve the fit
  • Passed ASTM F2100; ASTM F2100 level 2 for higher filtration efficiency (American Society for Testing and Materials)

N95, KN95 and KF94 masks

Properly fitted N95 (meet NIOSH standard) or KN95 and KN94 (meet international standard) offer extra protection from COVID-19. They filter COVID-19 particles better than other masks.

Read more about how to get the most out of masking.

Regardless of the mask type, you must wear it over your mouth and nose to be effective. The best mask is the one you wear consistently and correctly.

When to wear a more effective mask

It is better to wear an N95, KN95, KF94, double mask, or fitted medical mask when you are:

  • With people at higher risk of severe illness from COVID-19
  • Taking care of or living with people who have or been exposed to COVID-19
  • Indoors with unvaccinated people or where you don’t know if they are vaccinated
  • Indoors with poor ventilation
  • In crowded places where you cannot distance from other people

What not to use for COVID-19 prevention

Don’t use a mask or face covering with holes, including:

  • Halloween or plastic masks
  • Ski masks with holes for the nose or mouth
  • Masks that have a one-way valve designed for easier breathing (often a raised plastic disk about the size of a quarter, on the front or side of the mask)

Holes or one-way valves allow droplets out of the mask, exposing people nearby. If you wear one, you should wear another face covering on top that doesn’t have valves.

Keep it clean

If you’re outside your home and your face covering gets wet, have another face covering ready to replace it.

Wash your reusable face coverings frequently, ideally after each use. Wash in the warmest water possible, dry on the highest heat, and leave in the dryer until completely dry.

Clean your hands before and after touching your face, mask, or face covering.

The CDC has instructions on how to wear and clean your face covering

Last updated January 20, 2022