COVID-19

COVID-19 spreads when an infected person breathes out droplets and very small particles that contain the virus. These droplets and particles can then be breathed in by other people or land on their eyes, noses, or mouth.

• Masks help prevent the spread of COVID-19. They protect others from COVID-19 by containing the droplets and particles you breathe, cough, or sneeze out and if the mask fits and filters well, it protects you from breathing in particles spread by others.
• Respirators (i.e., specialized filtering masks such as “N95s, KN95s, and KF94s”) provide the highest level of protection. They filter very well and fit closely to your face, so they protect you from particles spread by others. They also protect others by containing droplets and particles that you breathe, cough, or sneeze out.

Know which masks provide the best protection against COVID-19.

• If you need the best protection, wear a well-fitting respirator. If a respirator is not an option, then the next best option is to wear a double mask (a well-fitting cloth mask over a medical mask) or a fitted medical mask.

Choose a mask:

1. That fits well. It should fit snugly against your nose and chin with no large gaps around the sides of the face or your nose, AND
2. Filters well, AND
3. That you will be comfortable wearing.

See CDC’s Types of Masks and Respirators and CDPH's Get the Most Out of Masking and Masks for Kids: Tips and Resources pages.
View CDC flyer-Important steps to choosing a mask

RESPIRATORS (such as N95, KN95, and KF94)

Respirators are specialized masks that are designed to filter out very small particles, including the virus that causes COVID-19. There are many types of respirators.

• N95 Respirators are disposable respirators that are designed to filter at least 95% of airborne particles. They are regulated by both the FDA (if marketed for medical purposes) and the CDC’s National Institute for Occupational Safety and Health (NIOSH). Lists of respirators that are NIOSH-approved can be found on the NIOSH-Approved Particulate Filtering Facepiece Respirators webpage. Note: Cal/OSHA requires that healthcare workers who wear N95s are ‘fit tested’ to find the right model, style, and size of N95. See FDA N95 Respirators for more information.
• KN95 Respirators are similar to N95s but are made to meet Chinese standards. KN95s are not regulated by NIOSH. These masks almost always have ear loops and look like a duck bill. Be aware that about 60% of KN95s sold in the US are fake. If you choose to use a KN95, it is recommended to find one that has been assessed by the National Personal Protective Technology Laboratory and found to have a minimum "filtration efficiency" of 95% or higher.
• KF94 Respirators are made to meet South Korean standards and are not regulated by NIOSH. They have side flaps and are a more rectangular horizontal “boat” shape compared to N95s/KN95s. They often have ear loops. They fit a wider range of face shapes and sizes. They are made to filter at least 94% of airborne particles.

Respirators that fit well and provide a tight seal on your face protect you better than a cloth mask or a medical mask. They may be less comfortable because they filter better and fit more tightly.

• When choosing a respirator, look at how well it fits and read the manufacturer instructions. These instructions should include information on how to wear, store, and clean or properly dispose of the respirator.
• To work well, respirators need to make a tight seal on your face. Find the right size, style, and model.
  • Respirators with straps that go around the back of the head provide a better seal than those with ear loops.
  • Respirators may not fit as well if you have facial hair.
  • Both KN95 and KF94s are both available in "child" or "extra-small" sizes, making them an option for children 2 years of age and older.
  • Different styles and sizes of respirators suit different people. You may need to try several kinds until you find one that provides a tight seal that you are comfortable wearing and don’t feel the need to constantly touch and adjust.
• Check the seal each time you put one on. See NIOSH instructions for how to put on, take off and check the seal of a respirator.
• If you have breathing difficulties check with your doctor before wearing a respirator.
• Do not wear an N95/KN95 with another mask (i.e., do not double mask).
• Beware of counterfeit (fake) respirators as they may not be able to provide the promised protection. Genuine respirators have certain markings printed on them - see appropriate N95 markings and KN95 markings.
  • NIOSH tips for warning signs of websites selling fake products and fake standard or approval markings (includes useful photos).
  • CDC Factors to Consider When Planning to Purchase Respirators from Another Country.

For more detailed information, see CDC Respirators.

MEDICAL MASKS

Also called surgical, medical procedure, disposable procedure, or dental masks. These include various types of loose-fitting disposable masks.

• Look for a mask that has a nose wire and at least three layers of non-woven or spun bound fabric and melt-blown fabric, which are often made of polypropylene.
• Improve the fit of the mask by either knotting its ear loops and tucking in its sides (see video) or by using a mask brace.
• Improve both the fit AND filtration of the mask by wearing it UNDER a well-fitting cloth mask (see Double masking).
• Medical masks should be resistant to fluids.
  • Tip: Test your mask with a drop of water on the front. The water should not soak into the mask. It should form beads on the surface.
• Follow the manufacturer’s instructions on how to wear, store, and clean or properly dispose of the mask. Do not wear a mask if it is wet or dirty.

Note: Some disposable masks are designed and tested to demonstrate that they perform to certain standards. These include the American Society for Testing and Materials (ASTM) standards F2100 or F3502. The most protective masks have a particle filtration efficiency of at least 95%. Look for masks that have been tested by an accredited third-party laboratory.

CLOTH MASKS

Cloth masks (also called reusable masks) work best if they are tight fitting and are made of certain materials that filter out small particles.

For better protection, wear a cloth mask OVER a medical mask (see Double masking).

• Good cloth masks have:
• Three layers or more. They should have at least two layers of tightly woven fabric plus one or more layer(s) of non-woven fabric. The non-woven fabric layer(s) could be a mask filter insert or a synthetic fabric such as melt-blown 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.
• Cloth masks without these features, such as two-layer cotton masks, bandanas, or gaiters are the least protective.
• Cloth masks are washable and re-usable. Be sure to read the mask’s care instructions. Some cloth masks become less effective if machine washed or dried.

Note: Some cloth masks are designed and tested to demonstrate that they perform at a consistent level. The American Society for Testing and Materials (ASTM) has set a standard (ASTM F3502) for barrier face coverings, including cloth ("reusable") masks. Masks rated as ASTM F3502-Level 2 for particle filtration provide better protection than Level 1. The most protective masks have a particle filtration efficiency of at least 95%. If you are considering purchasing a cloth mask that is not ASTM rated, look for one that has been tested by an accredited third-party laboratory. Ratings for some commercially available face masks are published on the CDC website Barrier Face Coverings and Workplace Performance/Performance Plus Masks.

• Wear a mask with nose wires.
• Use a mask fitter or brace—these devices are worn over a cloth or medical mask to reduce the leakage around the edges.
• Knot the ear loops close to the edge of the mask and tuck the excess material so there is no gap. See Knot and Tuck video.
• For children, use a smaller mask that fits them well.
• Certain types of facial hair, like beards, can make mask fitting difficult. People with beards can trim them, use a mask fitter/brace or double mask.

Tips to check that your mask fits

• Check for gaps by cupping your hands around the outside edges of the mask and feel for any air leakages. 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.
• If you have to continually adjust your mask, it might not fit properly. Consider trying different types or sizes of masks.

Wearing two masks or “double masking”

“Double masking” is when a well-fitting cloth mask is worn on top of a medical mask. This makes the medical mask fit better and adds extra layer(s) of protection.

Important note:

• Double masking does not work with two medical masks because they are too loose.
• Respirators should not be worn with a second mask, as this interferes with the fit.
• If you try double masking or other ways to improve the fit of your mask, make sure that you can still breathe comfortably and that your vision is not obstructed. Test it out at home first.

See CDC Use and Care of Masks and Maximizing Fit for Cloth and Medical Procedure Masks to Improve Performance and Reduce SARS-CoV-2 Transmission and Exposure, 2021.

The following people should not wear a mask:

• Children under age 2. Most children ages 2 to 8 can safely wear a mask with adult supervision.
• People who cannot safely wear a mask, such as someone who is unconscious, incapacitated, or who is unable to remove a mask without help.
• Workers in situations where wearing a mask would create a risk, as determined by local, state, or federal regulators or workplace safety guidelines.
• Anyone instructed not to wear a mask by their medical provider. If their job involves regular contact with others, they must wear a non-restrictive alternative, such as a face shield with a drape that is form fitting under the chin (see CDPH Face Shields), as long as their age and medical condition permits it.

Note: Underlying medical conditions

Most people with underlying medical conditions, including those with asthma, can wear a mask, unless instructed not to by their doctor. Wearing a mask does not reduce a person’s oxygen supply or cause a build-up of carbon dioxide. If you or someone you care for has an underlying health condition and you have concerns about wearing a mask, talk to your doctor.

Clear masks or masks with a clear plastic panel are an alternative type of mask for people who are or who interact with:

• People who are deaf or hard of hearing.
• Children or students learning to read.
• People learning a new language.
• People with disabilities.
• People who need to see the proper shape of the mouth for making appropriate vowel sounds

CDC and CA State mask guidance websites

• CDC Types of Masks and Respirators
• CDC Use and Care of Masks
• CDPH Get the Most Out of Masking
• CDC/NIOSH Respiratory Protection Information Trusted Source (information on respirators)

Resources

• CDC/NIOSH Barrier Face Coverings and Workplace Performance/Performance Plus Masks
• CDC Video Instruction to Improve Medical Mask Fit (Knot and Tuck Technique)
• CDC/NIOSH-How to Put on and Take off a Respirator (PDF)
• CDC/NIOSH-User Seal Check (PDF)
• CDC/NIOSH-Fit Testing (PDF)
• CDC Study - Maximizing Fit for Cloth and Medical Procedure Masks to Improve Performance and Reduce SARS-CoV-2 Transmission and Exposure