COVID-19 spreads ten meters or more when breathing

A statement issued by 239 scientists around the world to recognize and mitigate airborne transmission of COVID-19 to international health authorities will be published in the journal. Clinical infectious diseases.

The 239 signatories from 32 countries hail from many different areas of science and engineering, including virology, aerosol physics, flow dynamics, exposure and epidemiology, medicine and building engineering.

Led by internationally recognized professor of air quality and health, QUT professor Lidia Morawska, the appeal is to tackle the overwhelming research that finds an infected person exhaling virus droplets into the air by breathing and speaking that can travel beyond the current social distance requirement of 1.5m.

“Studies by signatories and other scientists have shown beyond reasonable doubt that viruses are exhaled in droplets small enough to stay airborne and pose an exposure risk of more than 1 to 2m per person. infected, “said Professor Morawska, director of the International Air Quality and Health Laboratory, said.

“At typical indoor air speeds, a 5 micron drop will travel tens of meters, much more than the scale of a typical room as it sits from a height of 1.5m above the floor.”

The signers of 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.

“Experience in many areas of science and engineering enables us to understand the characteristics and mechanisms behind the generation of respiratory droplets, how viruses survive in these droplets, and how air flow patterns transport microdroplets in buildings,” said the Professor Morawska.

Measures to be taken to mitigate airborne transmission include:

• Provide sufficient and effective ventilation (supply clean outside air, minimize recirculating air) particularly in public buildings, work settings, schools, hospitals, and nursing homes.
• Supplement general ventilation with airborne infection controls, such as local exhaust, high-efficiency air filtration, and germicidal UV lights.
• Avoid overcrowding, especially on public transportation and public buildings.

“These are practical and can be easily implemented and many are inexpensive. For example, simple steps like opening doors and windows can dramatically increase air flow rates in many buildings. Many health authorities are currently focusing on hand washing, maintaining the Social distancing and droplet precautions. Handwashing and social distancing are appropriate, but this is insufficient insight to provide protection against virus-carrying respiratory droplets released into the air by infected individuals. “

Professor Morawska said that several retrospective studies of the SARS epidemic had shown that airborne transmission was the most likely mechanism behind the spatial pattern of infections.

“For example, a recent study analyzed data and video records in a restaurant where three separate groups of diners contracted COVID-19, and found no evidence of direct or indirect contact between the three groups, but modeled how transmission occurred to through the air.

“We are concerned that people may think they are fully protected by current recommendations, but in fact, additional airborne precautions are needed to further reduce the spread of the virus.”

“Time to tackle the airborne transmission of COVID-19” will be published in Clinical infectious diseases.