Viral aerosols can travel up to 10 metres : Government

NEW DELHI: Recent studies pointing to SARS-CoV2, the virus that causes Covid-19, being transmitted through droplets and aerosols that can travel up to 10 metres in air have prompted the government to refine its advisory which calls for proper ventilation, among other things, to check the transmission of the disease.
Pitching for increased ventilation, the advisory, issued by the office of principal scientific advisor (PSA) to the government on Thursday, said droplets and aerosols become quickly concentrated and greatly increase the risk of transmission in “closed unventilated indoor” spaces.
“In closed indoor spaces, droplets, and aerosols become quickly concentrated, greatly increasing the risk of transmission to people in the area. Just as smells can be diluted by ventilation, high concentrations of the virus can be reduced by ensuring that outdoor air flows in,” said PSA, K VijayRaghavan, on the guidelines which enlisted steps on how to stop the transmission of Covid virus.
“One infected asymptomatic person can release enough aerosols to infect many. Symptoms can take up to two weeks to appear in an infected person, during which time they may continue to shed the virus to infect others. Some people may never show symptoms and yet be spreaders,” tweeted VijayRaghavan, a developmental biologist, on Thursday.
Besides underlining the importance of masks, distance and sanitation, the advisory also lays equal emphasis on ventilation, noting how infection transmission risk is much lower in outdoor areas, as virus particles get quickly dispersed. It said, “Better the ventilation, lower the potential for transmission.”
“Ventilation is a community defence that protects all of us at home or at work. Introducing outdoor air in offices, homes and larger public spaces is advised,” said the guidelines while suggesting ways to improve ventilation in these spaces on priority, both in urban and rural areas.
Fresh evidence and advice on airborne Covid-19 spread had come a few months ago when scientists at two laboratories of the Centre of Scientific & Industrial Research (CSIR) -- Centre for Cellular and Molecular Biology (CCMB) in Hyderabad, and Institute of Microbial Technology in Chandigarh -- had studied the extent of transmission through air.
The studies clearly noted the transmission among people who were suitably distanced but had shared enclosed spaces, like a closed room or vehicle. It suggested that the virus possibly travels in air to far greater distances than the two to three feet that was originally considered the zone of risk.