Geneva: The World Health Organization published new guidance Thursday, saying it can’t rule out the possibility that the coronavirus can be transmitted through air particles in closed spaces indoors, including in gyms and restaurants.
The WHO previously acknowledged that the virus may become airborne in certain environments, such as during “medical procedures that generate aerosols.” The new guidance recognizes some research that suggests the virus may be able to spread through particles in the air in “indoor crowded spaces.” It cited “choir practice, in restaurants or in fitness classes” as possible areas of airborne transmission.
“In these events, short-range aerosol transmission, particularly in specific indoor locations, such as crowded and inadequately ventilated spaces over a prolonged period of time with infected persons cannot be ruled out,” the United Nations health agency’s new guidance says.
The WHO said in its guidance that while early evidence suggests the possibility of airborne transmission in such environments, spread by droplets and surfaces could also explain transmission in those cases.
“However, the detailed investigations of these clusters suggest that droplet and fomite transmission could also explain human-to-human transmission within these clusters,” the guidance says.
The WHO added that more research is needed to further investigate preliminary findings. The agency says the main mode of transmission is still believed to be through respiratory droplets.
Airborne transmission of the coronavirus could occur if virus-carrying droplets “generate microscopic aerosols” by evaporating, the WHO said, or if “normal breathing and talking results in exhaled aerosols.” In theory, WHO says someone could inhale the aerosols and become infected. But it remains unknown, WHO says, if such aerosols would actually carry enough viable virus to cause infection.