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A short data thread that supports aerosols being key drivers of respiratory inf. disease transmission (vs. droplets). 1) Duguid (1946) showing that 96%, 99% and 94% of particles emitted while coughing, sneezing and speaking are <100 um in size.
2) "But bigger droplets can carry more virus!" This has not been shown experimentally, (if you find something please share!) Interestingly, Yan et al. found 20 times more influenza RNA (not infectious virus) on aerosols <5 um in size compared to aerosols >5 um in size.
3) Only aerosols under 100 um in size are the ones that are inhalable. See here EPA's plot of particle deposition fraction in the respiratory system for different aerosol sizes. Therefore, particles >100 um in size can only infect following a ballistic behavior onto mucosa/eyes.
I recognize that other fields define airborne transmission differently, but this has led to confusion regarding intervention controls (ventilation, air filtration, etc), especially when guidance is translated into other languages. Terminologies need to be reconciled among fields!
For more information regarding aerosol transmission, please check https://tinyurl.com/FAQ-aerosols , a great resource from @linseymarr @ShellyMBoulder @kprather88 @ProfCharlesHaas @CorsIAQ @jljcolorado + many other leading scientists in the field.
