Tuesday, January 11, 2022

Study shows that virus does not live long in the air

A new study by the University of Bristol's Aerosol Research Centre - still not peer-reviewed, unfortunately - suggests that viral particles in the air lose most of their infectivity (up to 90%) within as little as five minutes after becoming airborne.

What are the implications of this? It means that most COVID transmission is likely to happen at short distances, so mask wearing and physical distancing are paramount (and, by the same token, ventilation and hand-washing probably less so). The chances of being infected by transmission several metres across a room should therefore be considered slight; what you need to worry about are the people in your immediate vicinity.

The study seeks to replicate the environment in which most of us are exposed to the virus, rather than a more theoretical environment using Goldberg drums, which is what most older studies have relied on. It also shows that, the more humid the environment, the longer viral particles can survive without drying out and losing their infectivity. So, offices, planes, etc, are probably safer than gyms and restaurants, and a North American winter is probably safer than the summer (although that is tempered by the increased ability to remain outdoors in the summer). The actual temperature of the air seems to make very little difference to the virus' ability to survive in aerosol form.

These results do not include analysis of more recent variants like Omicron, although the team is starting experiments of newer variants in the coming weeks.

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