UC Davis Health is committed to providing you with the most up-to-date information and science on face masks and COVID-19. Learn why you should wear a face covering and which mask is the best to protect yourself and others:

Yes. Large amounts of research show that wearing a mask helps protect you from the coronavirus and it helps prevent you from transmitting it to someone else.

In June 2020, Gov. Gavin Newsom announced that Californians must wear face coverings or masks in public or high-risk places, including when shopping, taking public transit or seeking medical care. It mandates the use of face coverings by the general public when outside the home, with limited exceptions.

For those who are fully vaccinated against COVID-19, the CDC released updated guidance on April 27 that states they do not need to wear face coverings outdoors when alone or in a small group. However, vaccinated people should still wear masks in indoor public places and outdoors where there is increased risk of virus transmission, like concerts, sporting events and other crowded gatherings.

According to the California Department of Public Health (CDPH), the requirements include mandatory face coverings or masks in situations such as:

  • Inside or waiting to enter any indoor public space
  • Obtaining health care services
  • Waiting in line or riding in public transportation or ride-sharing services
  • At work in public spaces and while walking through common spaces
  • While outdoors when maintaining a physical distance of 6 feet or more isn’t possible

There are some exceptions to the mandate, which are listed on the CDPH’s website. Children age 2 and under, and people with a medical, mental health or a developmental disability that prevent them wearing a face covering, are among those exempted.

See our 5 tips to wear and care for your cloth face covering

The evidence has become even more powerful for wearing masks and social distancing. For instance, research shows that about 40% of COVID-19 infections are caused by people who don’t know they have the virus because their symptoms have not appeared yet. Wearing a face mask can help reduce novel coronavirus transmission to those wearing a mask and others nearby by as much as 65%.

The CDC issued new guidelines on Feb. 10 that say the best way to protect yourself from COVID-19 – along with social distancing – is to either wear two masks, with a cloth mask outside a surgical mask, or one tightly fitted mask with two or more layers. The CDC said lab tests showed people can reduce their exposure to COVID-19 by more than 95% if they wear two masks or adjust one surgical mask to fit more tightly by knotting the ear loops. The CDC report builds on a compilation of evidence by the Journal of the American Medical Association that demonstrates the effectiveness of masks against COVID-19.

Learn more about the effectivenes of two masks to protect against COVID-19

To prevent droplets from escaping, the face covering should cover both your nose and mouth at all times. When putting on or removing a face mask, use the ear loops on the side to ensure you don’t contaminate or touch any contaminated piece of the mask. Don’t touch eyes, nose or mouth when removing your face mask to avoid droplet spread.

Learn the mask safety do's and don'ts (PDF)

The most important thing is to pick materials you can breathe through. Currently, there is no recommendation for the most effective cloth for homemade masks. There are still a lot of unknowns about how droplets pass through cloth materials. Best practice is to look for fabrics that are very densely woven or knitted and have fibers that are packed together with smaller pores. This is where the difficult balance comes in. Fabrics that are easier to breathe through don’t block as much of the large droplets. Homemade masks don’t prevent transmission but can reduce the quantity and size of COVID-19 droplets you transmit or are you’re exposed to.

Get directions to make low-cost face masks for yourself and your family

Video: U.S. Surgeon General shows you how to make face masks from items around your house

Some of the new COVID-19 variants have been found to be more easily transmissible. Three-ply medical grade face masks provide the best protection. Wearing two different non-medical masks, one on top of the other, also provides better protection from the new COVID-19 strains than one face mask.

Face masks provide primary protection against COVID-19 transmission – wearing a face shield is supplemental. Face shields are not substitutes for masks and do not protect you or others as well as face coverings do.

Masks with filter ports can increase the spread COVID-19. They’re designed for people working around caustic fumes or chemicals – and they force out the air you’re breathing through the port. Instead of protecting someone from you, they propel your breath, and possibly droplets with the virus, even farther and more forcefully.

N95s with the filter in the middle also do not prevent someone from spreading the virus. They filter air coming in but do let air out.

Cloth face masks can and should be washed regularly (daily or multiple times per week). Cloth face coverings typically hold up well through repeated washing and wearing. Paper or surgical face masks should be changed out every few wears.

The plexiglass shields in stores and restaurants only help to somewhat dissipate COVID-19 droplets. They do not prevent the spread of virus through aerosols, which are currently being studied. The same is true for office cubicles. After a while, transmission is possible from aerosols if the air flow is not good. One way to think about this is if someone on the other side of the cubicle or plexiglass is wearing perfume, you eventually smell it. The same is true for how COVID-19 aerosols can travel. That’s why air flow is so important, along with other actions like wearing masks and social distancing.

Face coverings are typically not required when exercising outdoors alone (walking, hiking, bicycling, running, etc.) or with people who live with you, and when no one else is within 6 feet. However, you should still have a face covering with you in case you encounter a situation where you will be within 6 feet of other people.

The CDC released updated guidance on April 27 for people who are fully vaccinated. The new guidance states that people who are fully vaccinated against COVID-19 don't need to wear face coverings outdoors when alone or in a small group. However, vaccinated people should still wear masks in indoor public places and outdoors where there is increased risk of virus transmission, like concerts, sporting events and other crowded gatherings.

Children over the age of 2 should wear a face covering in public, unless they have a health reason not to, according to CDC guidelines. However, children under age 2 should not wear masks because they can be choking hazards, can cause breathing trouble and the bands that go around the head can be strangulation hazards. In addition, children of that age cannot reliably remove their mask on their own and could suffocate. View this video and story PDF from the UC Davis MIND Institute to help teach your child about wearing masks.

Parent resources to learn more about children and COVID-19