For countries that are currently considering the use of masks, WHO advises decision makers to apply a risk-based approach and consider the following:
Purpose of mask use: if the intention is preventing the wearer transmitting infection to others (that is source control) or to offer protection to the wearer against infection (that is prevention).
Risk of exposure to COVID-19
due to epidemiology/number of cases in the population: if there is high community transmission and other measures such as contact tracing or ability to carry out testing are not possible.
depending on occupation: e.g., individuals working in close contact with public (e.g., community health worker, cashier).
Vulnerability of the mask wearer/population: for example, if supplies are adequate medical masks could be used by people with comorbidities, such as cardiovascular disease or diabetes mellitus, older people, immunocompromised patients.
Setting in which the population lives: settings with high population density (e.g. refugee camps, those living in cramped conditions) and settings where individuals are unable to keep a safe distance (e.g. crowded buses or other transport).
Feasibility: availability and costs of masks, access to clean water to wash non-medical masks, and ability of mask wearers to tolerate adverse effects of wearing a mask.
Type of mask: medical mask versus non-medical mask (prioritization of medical masks for health care providers, symptomatic people and their caregivers).
In addition to these factors, potential advantages of the use of masks by healthy people in the community setting include reducing potential exposure risk from an infected person during the ‘pre-symptomatic’ period or if an infected person is asymptomatic.
There are potential risks and disadvantages that should be taken into account in any decision-making process on the use of masks:
Non-medical or cloth masks could increase potential for COVID-19 to infect a person if the mask is contaminated by dirty hands and touched often, or kept on other parts of the face or head and then placed back over the mouth and nose
Depending on the type of mask used, could cause difficulty in breathing
They can lead to facial skin breakdown
They can lead to difficulty with communicating clearly
They can be uncomfortable to wear
It is possible that mask use, with unclear benefits, could create a false sense of security in the wearer, leading to diminished practice of recognized beneficial preventive measures such as physical distancing and hand hygiene.