1/ More evidence potentially supporting aerosol transmission: tall people more likely to get COVID-19
Preprint recently published: taller men in UK, pre-lockdown, more like to get COVID-19. medrxiv.org/content/10.110…
HT @lavika
Preprint recently published: taller men in UK, pre-lockdown, more like to get COVID-19. medrxiv.org/content/10.110…
HT @lavika
2/ Creative idea.
- Drops fall quickly (within 1-2m). If they dominated, shorter people should have a higher chance of contagion
- Exhaled aerosols rise in cooler surroundings, due to buoyancy of the warmer exhaled air (e.g. Chen et al. (2020) sciencedirect.com/science/articl…)
- Drops fall quickly (within 1-2m). If they dominated, shorter people should have a higher chance of contagion
- Exhaled aerosols rise in cooler surroundings, due to buoyancy of the warmer exhaled air (e.g. Chen et al. (2020) sciencedirect.com/science/articl…)
3/ We have also seen this effects in initial experiments trying to characterize the close proximity situation, by measuring CO2 at different heights in front of a person speaking. The data below, taken by Dr. @djpagonis in our group, shows the CO2 concentration while speaking...
4/ with CO2 measured at 3 different heights (z = 0 is mouth height, other values higher) & as a function of horizontal distance from mouth. Indeed CO2 enhancement is significantly larger above mouth height. Small enough aerosols (e.g. 10 um) settle very slowly and... 
5/ will just follow the same dispersion pattern as the CO2.
The pattern of higher cases for tall men is consistent with aerosols being more important than droplets. An interesting result. Hopefully it can be explored with other databases to see if the trend also holds in those
The pattern of higher cases for tall men is consistent with aerosols being more important than droplets. An interesting result. Hopefully it can be explored with other databases to see if the trend also holds in those
6/ Would be curious to hear comments about paper from ppl who do that kind of study (in terms of statistical strength of results).
- Also if you have this kind of data, pls analyze and see if you see same trend or not.
- Also if you have this kind of data, pls analyze and see if you see same trend or not.
7/ PS 12 h later:
- Nobody questioned physics & possibility of height effect
- Lots of knowledgeable ppl question the robustness of this particular study. So I would call results so far as inconclusive
- Importantly some calls to look at it w/ larger datasets, would be v useful
- Nobody questioned physics & possibility of height effect
- Lots of knowledgeable ppl question the robustness of this particular study. So I would call results so far as inconclusive
- Importantly some calls to look at it w/ larger datasets, would be v useful
8/ PS2 Updated data from @djpagonis , including data closer to the mouth. Shows CO2 highest at mouth height near the mouth, then plume rise makes CO2 higher above mouth height at 0.5-1 m (US convers. distance)
- (Only prelim data, but useful to illustrate)
- (Only prelim data, but useful to illustrate)
9/ PS3: Actually Liu et al. (2016 onlinelibrary.wiley.com/doi/full/10.11…) already showed experimentally this effect of height on exposure.
- So more evidence physical effect for exposure is real.
- Impact on real transmission TBD.
HT Bill Nazaroff & @djpagonis
- So more evidence physical effect for exposure is real.
- Impact on real transmission TBD.
HT Bill Nazaroff & @djpagonis
