The U.S. Centers for Disease Control and Prevention (CDC) has reported that the virus that causes COVID-19 can spread in the air, sometimes for hours.
In doing so, they recognized the concerns, which have been expressed by many health experts, that the virus could be spread by airborne droplets.
The CDC’s guidelines, released on Monday, said the available evidence indicates that people with COVID-19 may have infected others who were more than two meters away when in enclosed spaces with poor ventilation.
The CDC reported that, according to scientists, in such conditions, the concentration of infectious small droplets and particles, or aerosols, which are produced by patients with COVID-19, becomes high enough for the spread of the virus.
For a long time, the CDC claimed that the virus spreads through small droplets that fly through the air and usually fall to the ground, which was the basis for the social distancing rule of two meters.
Aerosol particles are much smaller in size and can remain in the air for a long time, like smoke.
While the CDC emphasizes that close human-to-human transmission is more common, a team of American scientists warned in a separate open letter published in Science on Monday that airborne aerosols could be the main source of COVID-19 transmission.
“The reality is that airborne transmission is the main mode of transmission at close range with prolonged contact,” the scientists said at a press conference.
In aerosols, viruses can remain in the air for seconds to hours, travel more than two meters and accumulate in poorly ventilated areas, which can lead to infections in large numbers of people, the researchers said.
Some people with COVID-19 give off thousands of aerosolized particles with the virus and much fewer droplets when breathing and talking. Therefore, scientists insist that the main attention should be paid to protecting against transmission of the virus by airborne droplets.
They also noted that health authorities must make a clear distinction between droplets from coughs and sneezes and aerosols that can carry the virus over long distances.
The letter says that health authorities should emphasize the importance of moving activities and work to the open air and improving indoor air quality, along with wearing masks and social distancing.