WHO tightens guidelines on COVID masks for public, health workers

Masks should also be worn outdoors and in well ventilated indoor spaces where physical distancing of at least one meter (3 ft) could not be maintained.

In all scenarios, masks - which protect against transmission of the virus rather than infection - needed to be accompanied by other precautions such as hand-washing, the WHO said.

In areas of COVID-19 spread, it also advised "universal" wearing of medical masks in health care facilities, including when caring for other patients.

The advice applied to visitors, outpatients and to common areas such as cafeterias and staff rooms.

Health care workers could wear N95 respirator masks if available when caring for COVID-19 patients, but their only proven protection is when they are doing aerosol-generating procedures which carry higher risks, the WHO said.

It recommended that people doing vigorous physical activity not wear masks, citing some associated risks, particularly for people with asthma.

Adequate ventilation, physical distancing and disinfection of "high-touch surfaces" in the gym must be maintained, or their temporarily closure should be considered, it added.