From Times of India, Oct 2020
On Monday the 5th of October 2020, the U.S. Centers for Disease Control and Prevention (CDC) said that COVID-19 would spread by airborne viruses, often for hours, recognising concerns commonly raised by public health experts about airborne virus transmission.
The CDC advice comes weeks after a similar alert, stirring discussion about how the virus spreads, was released by the agency-and then taken down. In Monday's guidance, the CDC said there was evidence that individuals with COVID-19 could have contaminated people, who were more than 6 feet away, inside enclosed spaces with inadequate ventilation.
Under such circumstances, CDC said that scientists assume that the amount of infectious smaller droplets and particles or aerosols generated by COVID-19 individuals is sufficiently concentrated to spread the virus. The CDC has long warned of transmission by tiny droplets that shoot through the air and normally fall to the ground, resulting in the social distancing of six feet rule.
Aerosol droplets are still much smaller and can, like smoke, stay suspended in the air. A group of U.S. scientists cautioned in an unrelated open letter published in the medical journal Science on Monday that aerosols remaining in the air may be a major source of COVID-19 transmission, although the CDC emphasises that close-contact transmission is more normal than via air.
The fact is that airborne transmission is the predominant way that transmission occurs with prolonged contact at close range, ” the researchers said in a press conference. Aerosol viruses can linger in the air for seconds to hours, fly more than two metres, and accumulate in indoor air that is poorly ventilated, leading to events that are superspreading, the researchers said.
Since people with COVID-19 emit thousands of aerosols filled with viruses and far fewer droplets when breathing and speaking, the researchers said the emphasis must be on protecting against airborne transmission. They also said that public health officials should clearly distinguish between droplets ejected by coughing or sneezing and aerosols that can take more distance from the virus Public health officials should stress the importance of moving activities outdoor and enhancing the indoor air, , along with wearing mask and social distancing, the letter said.
REFERENCE Chander, V. and Ganguli, S., 2020. CDC Revises Guidance, Says COVID-19 Can Spread Through Virus Lingering In Air - Times Of India. [online] The Times of India. Available at: