10-23-2020, 01:20 PM
A couple of numbers:
The infectious dose of SARS-CoV (the original SARS virus) is estimated at 300 or so viral particles (this is typically represented as an ID50, or the dose that causes infection in 50% of people) https://onlinelibrary.wiley.com/doi/full...10.01427.x. The infectious dose of SARS-CoV-2 which causes COVID-19 is probably similar.
Normal talking can generate up to 3000 1-micron particles per minute in exhaled breath,4 and each particle could contain more than 250 virions, which means that a single minute of speaking potentially generates more than 750,000 virions. (link, it is in the second letter). Obviously, the longer the exposure, the more particles are generated.
Figuring out how many of those viruses end up being inhaled by the exposed individual is complicated and is affected by a whole host of issues, including mask-wearing, distance, confinement, ventilation, etc.
Risk = exposure x time.
BC
The infectious dose of SARS-CoV (the original SARS virus) is estimated at 300 or so viral particles (this is typically represented as an ID50, or the dose that causes infection in 50% of people) https://onlinelibrary.wiley.com/doi/full...10.01427.x. The infectious dose of SARS-CoV-2 which causes COVID-19 is probably similar.
Normal talking can generate up to 3000 1-micron particles per minute in exhaled breath,4 and each particle could contain more than 250 virions, which means that a single minute of speaking potentially generates more than 750,000 virions. (link, it is in the second letter). Obviously, the longer the exposure, the more particles are generated.
Figuring out how many of those viruses end up being inhaled by the exposed individual is complicated and is affected by a whole host of issues, including mask-wearing, distance, confinement, ventilation, etc.
Risk = exposure x time.
BC