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Division of Communicable Disease Control​
Woman wearing backpack with mask on in airport.

When and Why to Wear a Mask

The Benefits of Masking and Tips for Choosing the Right Mask

Wearing a high-quality mask that fits well and has good filtration helps to protect you from breathing in viruses, wildfire smoke, and other particles or germs in the air. 

Respirators, such as N95s, KN95s, or KF94s, are the best type of masks. They offer more protection because they generally have better fit and filtration. Other masks such as surgical masks and cloth face coverings, tend to be looser and not as protective as respirator masks. N95, KF94 and KN95 respirators can be purchased at drugstores, hardware supply stores, and online. 

Mask wearing may be an especially good precaution for anyone who is at higher risk for getting very sick from respiratory illnesses, has a history of breathing/lung issues, or has environmental exposures.  ​

​When to Consider Wearing a Mask

Protection Against Respiratory Viruses​

Masks lower a person’s exposure to respiratory infections such as COVID19, influenza, respiratory syncytial virus (RSV) and pertussis (whooping cough). 

If you test positive for COVID-19, masking for 10 days is recommended. See COVID-19 isolation guidance for more details. 

If you believe you were exposed and will be in contact with someone who is higher risk, consider wearing a high-quality mask.   

If you are at higher-risk of becoming severely ill, consider wearing a high-quality mask (respirator) when you are in an indoor public setting with poor ventilation, or when you are traveling on public transportation.  

People who are at higher risk for severe respiratory infections include: 

  • Older adults (aged 50 years and older)

  • People with certain medical conditions such as a chronic disease or cancer

  • People with weakened immune systems

  • People who are pregnant or were recently pregnant

  • People with disabilities

  • People who live in congregate care facilities, such as a skilled nursing facility

  • Children under 5, with greatest risk in infants​

Protection Against Harmful Environmental Exposures

Below are a few examples of when masks are highly recommended during an environmental exposure. 

Wildfire Smoke

When a wildfire, wildfire smoke, or poor air quality is in your area, wearing an N95 respirator can help filter out harmful smoke particles, if you must go outside. When fitted correctly, an N95 respirator that fits over the nose and mouth can significantly reduce breathing in harmful particles. 

Valley Fever

In certain areas of California, the fungus that causes Valley fever grows in the soil and may be in outdoor dust. While working or spending time outdoors in dusty areas where Valley fever is common, wear a properly fitted mask approved by theNational Institute for Occupational Safety and Health (NIOSH). A N95 or higher-level respirator, may help protect you from breathing in dust and fungal spores that can cause Valley fever. Learn more about Valley fever safety in the workplace and Valley fever prevention. 

​Choosing the right mask​

​High Quality​

N95s

N95 respirators offer the best protection. Adults should choose an N95 respirator approved by NIOSH. N95s have two head straps and a tight fit. Authentic NIOSH-approved N95 respirators should have specific markings. Learn more about counterfeit (fake) respirator masks and how to use N95 respirators.  ​​​
N95s mask picture

KN95s and KF94s

KN95s and KF94s are respirators that meet international standards. They provide good protection, but less protection than N95s. Most KN95s and KF94s have ear loops, which may provide a less-snug fit than respirators with head straps such as N95s. 

If you choose to use a KN95 or KF94, use one that has been tested by NIOSH and has a minimum "filtration efficiency" of 95% or higher. While these respirators have been tested by NIOSH, they are not designed and approved according to NIOSH standards. ​​

KN95s and KF94s masks

Surgical Masks

Surgical masks include various types of loose-fitting disposable masks. These masks can block large droplets but dont fit close to the face. Even when worn tightly against your face, surgical masks provide much less protection than a well-fitting respirator. 

Surgical mask picture​​

Cloth Masks

Cloth masks are less protective than surgical masks or high-quality respirators. 

Cloth mask picture

Fit

A mask should fit snugly to your face, covering both your nose and mouth, with no gaps between the mask and your skin. If your mask has any gaps, it will allow the flow of unfiltered air into your lungs. Also, any facial hair will prevent the mask from working properly. Maintain a clean shave (PDF), if possible. 
Face mask picutre
 

Check for any 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. 

Change your mask as needed. Do not wear a dirty mask. Throw away disposable masks or respirators that become wet or dirty. ​

For Ch​ildren

Masks can be worn safely by children 2 years of age and older. There are rare exceptions. Children under age 2 should not wear a mask. Choose a mask for your child that has the best protection, best fit, and one your child will wear. 

Masks should fit over the nose and under the chin with no gaps around the edges. They should not prevent your child from seeing. KN95s and KF94s are both available in “child” or “extra-small” sizes. N95s in size “small” may fit older children but may not fit younger or smaller children. There are no NIOSH-approved N95 masks for children at this time. ​

Who Sh​ould NOT Wear a Mask​

Wearing a mask may be difficult for people with sensory, cognitive, or behavioral issues. Masks are not recommended for children under 2 years of age. They are also not recommended for persons who have trouble breathing or are unconscious, incapacitated or otherwise unable to remove the mask without help. Mask wearing can also be hard for people who are hearing impaired or are communicating with a person who is hearing impaired because seeing the mouth may be needed to communicate. 

Other Considerations

Any person who chooses to wear a mask cannot be excluded from participating in an activity or entering a venue or business (including schools or childcare) unless wearing a mask would pose a safety hazard.  

This information is intended for a general audience. Some workplaces (PDF), local health departments, and Cal/OSHA may have additional recommendations or requirements for wearing a mask. ​

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