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Why do aerosols and droplets cause so much drama? A thread 
It really all stems from a long-standing error in the medical literature on the size of droplets: Particles that behave as droplets were long believed to be >5um. This, it turns out, is incorrect.
1/ https://twitter.com/jenniferkshea/status/1338662502931034113
It really all stems from a long-standing error in the medical literature on the size of droplets: Particles that behave as droplets were long believed to be >5um. This, it turns out, is incorrect.
1/ https://twitter.com/jenniferkshea/status/1338662502931034113
Aerosol scientists have known for decades that their actual size is >100um and that smaller particles behave as aerosols that can stay suspended in the air. Unfortunately the medical literature continued to repeat and perpetuate this fundamental error until just recently.
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More than 94% of what we send out of our noses and mouths when we talk/sneeze/cough is <100um. If you believe that droplets can be as small as 5um, then you would consider these particles to be droplets that will fall to the ground quickly.
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But droplets are >100um. That part isn't up for debate, it's a verifiable scientific fact. So once the 'original sin' of droplet transmission science is corrected, it follows that 94%+ of what we exhale are aerosol sized
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They're small enough to stay suspended in the air and can travel further than 2m. However, the density of the aerosols you're exposed to is still highest at close range, so the mantra of being *most* at risk at close range (or less than 2m) still holds true.
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What changes is the realization that you can also be infected at a distance, particularly indoors. So along with distancing, masks and air quality control are also cornerstones of infection prevention.
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Aerosols aren't just one mode of COVID19 transmission, the evidence is mounting every day that they're the primary mode of transmission. And much of the debate simply stems from the 'original sin.' Many are still calling small aerosol-sized particles 'droplets'. That's it.
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And the reason so many of us are advocating so strongly that all of this be clarified and recognized is that we believe the public wants to know how to best protect themselves. And clearly, judging by transmission rates, holding tight to the old dogma is failing them.
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Just to clarify: by air quality control, I mean ventilation. No thread on aerosols is complete without mentioning the importance of proper ventilation of indoor spaces!
