Indoor precautions essential to stem airborne COVID-19

The study reports ventilation systems in cruises could have spread the virus between passengers.

Summary: Researchers urge health officials to recognize and inform the public that airborne transmission of COVID-19 from droplets expelled by an infected person can spread beyond six feet. The study reports ventilation systems in cruises could have spread the virus between passengers. Measures to reduce indoor viral airborne transmission are proposed.

Source: Queensland University of Technology

World-leading air quality and health expert QUT Professor Lidia Morawska and Professor Junji Cao from Chinese Academy of Sciences in an article in Environment International published this week called on health bodies to initiate research into the airborne transmission of COVID-19 as it is happening.

“National health bodies responsible for controlling the pandemic are hampered by not acknowledging the research evidence of airborne transmission of viable virus droplets, that was conducted after the SARS 2003 outbreak,” Professor Morawska said.

“Now is the ideal time to conduct research into how viruses can travel on the airflow because there are many similarities between the coronavirus that caused SARS and the COVID-19 coronavirus and therefore it is highly likely that COVID-19 spreads by air.

“Analysis of the initial pattern of COVID-19 spread in China reveals multiple cases of non-contact transmission, especially in areas outside Wuhan.

“On numerous cruise ships where thousands of people onboard were infected, many of the infections occurred after passengers had to isolate in their cabins even though hand hygiene was implemented.

“Therefore, the ventilation system could have spread the airborne virus between the cabins.

“We know that COVID-19’s predecessor, SARS.CoV-1 did spread on the air in the 2003 outbreak. Several studies have retrospectively explained this pathway of transmission in Hong Kong’s Prince of Wales Hospital as well as in healthcare facilities in Toronto, Canada.

This shows how air droplets travel
Tiny virus droplets travel on airflow. The image is credited to QUT: Chantal Labbe.

“A WHO review (2009) of the evidence found viral diseases can be transmitted across distances in indoor environments by aerosol or airborne infection and can result in large clusters of infection in a short period.”

Professor Morawska said authorities need to put in place public health precautions to lower airborne transmission by:

  • increased ventilation of indoor spaces
  • use of natural ventilation
  • avoiding air recirculation
  • avoiding staying in another person’s direct air flow
  • minimizing the number of people sharing the same environment
  • providing adequate ventilation in nursing homes, hospitals, shops, offices, schools, restaurants and cruise ships.

Professor Morawska said virus droplets’ liquid content started to evaporate immediately after being exhaled and some became so small that could travel on air currents, rather than fall to the ground as larger droplets do.

“Such small droplets can carry their viral content meters, even tens of meters, away from the infected person.”

Professor Morawska said it was difficult to directly detect viruses traveling in the air because it took knowledge of the airflow from an infected person and a long sampling period to collect enough copies of the viruses.

“Air transmission research should be undertaken now and its likelihood as a means of spread should be taken seriously with due precautions taken now.

“We have already lost valuable time by ignoring this method of spread and we should act on the presumption that COVID-19 is spreading on the air.”

About this coronavirus research article

Queensland University of Technology
Media Contacts:
Niki Widdowson – Queensland University of Technology
Image Source:
The image is credited to QUT: Chantal Labbe.

Original Research: Open access
“Airborne transmission of SARS-CoV-2: The world should face the reality”. by Lidia Morawska, Junji Cao.
Environment International doi:10.1016/j.envint.2020.105730.


Airborne transmission of SARS-CoV-2: The world should face the reality

Hand washing and maintaining social distance are the main measures recommended by the World Health Organization (WHO) to avoid contracting COVID-19. Unfortunately, these measured do not prevent infection by inhalation of small droplets exhaled by an infected person that can travel distance of meters or tens of meters in the air and carry their viral content. Science explains the mechanisms of such transport and there is evidence that this is a significant route of infection in indoor environments. Despite this, no countries or authorities consider airborne spread of COVID-19 in their regulations to prevent infections transmission indoors. It is therefore extremely important, that the national authorities acknowledge the reality that the virus spreads through air, and recommend that adequate control measures be implemented to prevent further spread of the SARS-CoV-2 virus, in particularly removal of the virus-laden droplets from indoor air by ventilation.

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