Hundreds of international scientists are urging the World Health Organisation to revise its guidelines about the airborne transmission of coronavirus.In an open letter, 239 experts from 32 countries point to new research that shows an infected person exhales airborne virus droplets when breathing and talking that can travel further than the current 1.5m social distance requirement.The research, from Queensland University of Technology, shows poor ventilation in public buildings, workplace environments, schools, hospitals, aged care homes, or activities such as singing, contribute to viral spread.
Improved ventilation is vital for protecting against airborne infection transmission, the scientists warned.Led by Professor Lidia Morawska, the experts say the 1.5 metre social distancing rule is not far enough.”Studies by the signatories and other scientists have demonstrated beyond any reasonable doubt that viruses are exhaled in microdroplets small enough to remain aloft in the air and pose a risk of exposure beyond 1m to 2m by an infected person,” Professor Morawska said.”At typical indoor air velocities, a five-micron droplet will travel tens of metres, much greater than the scale of a typical room while settling from a height of 1.5m above the floor.”
Signatories to the appeal come from many disciplines including different areas of science and engineering, including virology, aerosol physics, flow dynamics, exposure and epidemiology, medicine, and building engineering.
Professor Morawska said there are affordable simple measures that can be taken to lessen the risk of airborne infection in buildings:
- Provide sufficient and effective ventilation (supply clean outdoor air, minimise recirculating air) particularly in public buildings, workplace environments, schools, hospitals, and aged care homes.
- Supplement general ventilation with airborne infection controls such as local exhaust, high efficiency air filtration, and germicidal ultraviolet lights.
- Avoid overcrowding, particularly in public transport and public buildings.
“Hand-washing and social distancing are appropriate, but it is view, insufficient to provide protection from virus-carrying respiratory microdroplets released into the air by infected people,” she said.The appeal is to be published in the journal Clinical Infectious Diseases.