12th May 2020

Can you catch SARS-CoV-2 through a viral cloud?

12th May 2020

Curated by Endre Szvetnik

Recent research shows that the novel coronavirus can stay in the air for some time, but whether it is likely to cause infection is very conditional.

This depends on the size of virus particles. Droplets, which are the larger ones (over 5 micrometres), don’t travel further than 1 metre and quickly fall on a surface. They are released through coughing, sneezing or speaking. Aerosols are smaller than 5 micrometres, can travel up to 4 metres and can stay in the air for up to 3 hours, but their concentration would be dangerous only in certain cases.

What are those cases? Can I walk into a viral cloud and get sick? Chinese research found SARS-CoV-2 aerosols in two Wuhan hospitals. High concentrations were only detected in confined spaces, such as unventilated toilets or crowded areas. In contrast, concentrations were very low in ventilated patients’ rooms. Another study found an additional hotspot: areas where medical staff removed their contaminated protective equipment. As to the outdoors, such as parks, a Dutch study using computational fluid dynamics simulation observed particle clouds created by walkers, runners and cyclists and suggested that people should keep a 4, 9 or 20-metre distance to avoid aerosols. However, the research did not look at viral levels in aerosols and could not inform about specific SARS-CoV-2 infection risk. The above studies of ventilated indoor spaces suggest that aerosols would carry even less viral particles in the open than indoors.

Here is the current state of science on a Sparrho pinboard. NB: The pinboard contains research papers that have not been peer-reviewed yet, meaning that they have not gone through the standard scientific validation process yet.

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Curated by

Endre Szvetnik

Endre Szvetnik is Senior Editor at Sparrho. Endre works with Sparrho Heroes to curate, translate and disseminate scientific research to the wider public.

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