Coronavirus disease (COVID-19): Masks

Masks are a key measure to reduce transmission and save lives.

Wearing well-fitted masks should be used as part of a comprehensive ‘Do it all!’ approach including maintaining physical distancing, avoiding crowded, closed and close-contact settings, ensuring good ventilation of indoor spaces, cleaning hands regularly, and covering sneezes and coughs with a tissue of bent elbow.

Depending on the type, masks can be used for either protection of healthy persons or to prevent onward transmission, or both.

There are three types of masks that WHO recommend for the public: 

• Reusable non-medical masks which comply with the ASTM F3502 standard or CEN Working Agreement 17553, or a non-medical mask meeting WHO essential parameters; 
• Disposable medical masks which comply with medical mask standards EN 14683 Type I, ASTM F2100 Level 1, YY/T 0969, YY 0469 (or equivalent); 
• Other types of well-fitting non-medical masks, including homemade multi-layered masks are an acceptable option, when other options are not available. 

Disposable medical masks are also recommended for the following groups, because if infected, they are at a higher risk of becoming seriously ill with COVID-19 and dying:

• People aged 60 or over.
• People of any age with underlying health conditions, including chronic respiratory disease, cardiovascular disease, cancer, obesity, immunocompromised patients and diabetes mellitus. 

Disposable medical masks are also recommended for:

• Anyone who is feeling unwell, including people with mild symptoms, such as muscle aches, slight cough, sore throat or fatigue.
• Anyone awaiting COVID-19 test results or who has recently tested positive.

A respirator or a medical mask should be worn by to caregivers at any setting where care is provided to patients with suspected or confirmed COVID-19, including home care, long-term care facilities and community care settings

In settings where there is community or cluster transmission of SARS-CoV-2, irrespective of vaccination status or history of prior infection, wearing a well-fitting mask that covers the nose and mouth is recommended for the public when interacting with individuals who are not members of their household:

• in indoor settings where ventilation is known to be poor or cannot be assessed, or the ventilation system is not properly maintained, regardless of whether physical distancing of at least 1 metre can be maintained;
• in indoor settings that have adequate ventilation if physical distancing of at least 1 metre cannot be maintained; or
• in outdoor settings where physical distancing of at least 1 metre cannot be maintained.

It’s not always easy to determine the quality of ventilation. If you have any doubts, it’s safer to simply wear a mask. While wearing a mask, you should continue to maintain physical distance from others as much as possible. Wearing a mask does not mean you can have close contact with people.

A respirator or a medical mask should be worn by health workers along with other personal protective equipment (PPE) – a gown, gloves and eye protection – before entering a room where there is a patient with suspected or confirmed COVID-19, including home care, long-term care facilities and community care settings.

Respirators should be worn in the following situations:

• in care settings where ventilation is known to be poor* or cannot be assessed or the ventilation system is not properly maintained
• based on health workers’ values and preferences and on their perception of what offers the highest protection possible to prevent SARS-CoV-2 infection.
  

A respirator should always be worn along with other PPE (gown, gloves and eye protection) by health workers performing aerosol-generating procedures (AGPs) and by health workers on duty in settings where AGPs are regularly performed on patients with suspected or confirmed COVID-19, such as intensive care units, semi-intensive care units or emergency departments.

Medical masks (also known as surgical masks) are:

• composed of 3 layers of synthetic nonwoven materials
• configured to have filtration layers sandwiched in the middle
• available in different thicknesses
• have various levels of fluid-resistance and filtration

Respirators (also known as filtering facepiece respirators – FFP) are available at different performance levels such as FFP2, FFP3, N95, N99, N100.

Medical masks and respirator masks are similar in their filtration value. However, respirators also have a tight fit around the wearer face as the model and size of the respirator is specific to the wearer to ensure an adequate seal. Respirator masks are designed to protect health workers who provide care to COVID-19 patients in settings and areas where aerosol generating procedures are undertaken. They are also recommended for health workers providing care to suspected or confirmed COVID-19 patients in settings where ventilation is known to be poor or cannot be assessed or the ventilation system is not properly maintained

Health workers should be fit tested before using a respirator to ensure that they are wearing the correct size. Wearing a loose-fitting respirator will not offer the same level of protection to the wearer as it may allow small particles to get inside the mask where there are gaps, for example through the side.

Filtration, breathability and fit are all important.

If you purchase a non-medical mask, check the labels to make sure it complies with the ASTM F3502 standard or CEN Working Agreement 17553.

If you choose to make your own mask, it should be made of three layers of fabric:

• Inner layer of absorbent material, such as cotton.
• Middle layer of non-woven non-absorbent material, such as polypropylene.
• Outer layer of non-absorbent material, such as polyester or polyester blend.

Watch the video on WHO’s recommended fabric mask materials and composition for more information.

For either type of mask, you should choose the one that fits your face well - cover your nose, cheeks and chin without leaving gaps on the sides. Masks with vents or exhalation valves are not advised because they allow unfiltered breath to escape the mask.

Health workers are the most likely to be exposed to COVID-19 because they are in close contact with patients with suspected, probable or confirmed COVID-19.

In areas of community or cluster transmission, health workers, caregivers and visitors should wear a mask at all times when in the health facility, even if physical distancing can be maintained. Masks should be worn throughout their shifts, apart from when eating, drinking or needing to change the mask for specific reasons:

• Health workers and caregivers include: doctors, nurses, midwives, medical attendants, cleaners, community health workers, and any others working in clinical areas.
• Health workers must remember to combine hand hygiene with any time they touch their mask or face, before and after putting on and removing their masks, as well as before they touch them to readjust them.

In settings where there is community or cluster transmission of SARS-CoV-2, health workers in clinical areas should wear medical masks throughout their shift apart from when eating, drinking or needing to change the mask for specific reasons.

Health workers should continue to physically distance and avoid unnecessary close contact with colleagues and others in the facility when not providing patient care.

Further resources:

• Healthcare workers can complete our OpenWHO course on how to put on and remove personal protective equipment.
• Read our guidance on ‘Infection prevention and control during health care when coronavirus disease (‎COVID-19)‎ is suspected or confirmed’.

How to put on and wear a fabric mask:

• Before touching the mask, clean your hands with an alcohol-based hand rub or soap and water.
• Inspect the mask for tears or holes, do not use a mask that is damaged.
• Adjust the mask to cover your mouth, nose, and chin, leaving no gaps on the sides.
• Place the straps behind your head or ears. Do not cross the straps because this can cause gaps on the side of your face.
• Avoid touching the mask while wearing it. If you touch it, clean your hands.
• Change your mask if it gets dirty or wet.

How to take off and store a fabric mask:

• Clean your hands before taking off the mask.
• Take off the mask by removing it from the ear loops, without touching the front of the mask.
• If your fabric mask is not dirty or wet and you plan to reuse it, put it in a clean resealable bag. If you need to use it again, hold the mask at the elastic loops when removing it from the bag. Clean your mask once a day.
• Clean your hands after removing the mask.

How to clean a fabric mask:

• Wash fabric masks in soap or detergent and preferably hot water (at least 60 degrees Centigrade/140 degrees Fahrenheit) at least once a day.
• If it is not possible to wash the mask in hot water, then wash it in soap/detergent and room temperature water, followed by boiling the mask for 1 minute.

Watch our ‘How to wear a fabric mask’ video for a demonstration.

How to put on and take off a medical mask:

• Before touching the mask, clean your hands with an alcohol-based hand rub or soap and water.
• Inspect the mask for tears or holes; do not use a mask that has previously been worn or is damaged.
• Verify which side is the top – this is usually where the metal strip is.
• Then, identify the inside of the mask, which is usually the white side.
• Place the mask on your face covering your nose, mouth and chin, making sure that there are no gaps between your face and the mask. Place the straps behind your head or ears. Do not cross the straps because this can cause gaps on the side of the mask.
• Pinch the metal strip so it moulds to the shape of your nose.
• Remember, do not touch the front of the mask while using it to avoid contamination; if you accidentally touch it, clean your hands.

How to take off a medical mask:

• Before touching the mask, clean your hands with an alcohol-based hand rub or soap and water.
• Remove the straps from behind the head or ears, without touching the front of the mask.
• As you remove the mask, lean forward and pull the mask away from your face. 
• Medical masks are for single use only; discard the mask immediately, preferably into a closed bin.
• Clean your hands after touching the mask.
• Be aware of the condition of the mask; replace it if it gets soiled or damp.

Even when you’re in an area of COVID-19 transmission, masks should not be worn during vigorous physical activity because of the risk of reducing your breathing capacity. No matter how intensely you exercise, keep at least 1 metre away from others, and if you’re indoors, make sure there is adequate ventilation.