The Guangzhou restaurant suggested that air currents resulted in exposure to airborne droplets that could have been inhaled. But yes, because there wasn't widespread transmission throughout the restaurant, that argues against small particle aerosols. IMO the main issue here is...
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Replying to @angie_rasmussen @geunsmeyer and
...what people mean when they say "aerosols" or "airborne". Different disciplines mean different things, and that's different from how the general public understand these terms, adding to the confusion. This is a communication issue and that's why the terminology needs revising.
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Replying to @angie_rasmussen @geunsmeyer and
Maybe we will need to consider the role of A/C for indoors, and focus on behavior, not just size. If it were classic aerosol (to stabilize terminology, say, < 5 μm) spread for Guangzhou case, why were only people down-wind of the A/C currents infected, but not one table over?
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Replying to @zeynep @geunsmeyer and
We do certainly need to focus on air flow, as well as behavior, but that's why "airborne" and "aerosol" need updating. The downwind effect suggests that it probably wasn't small particle aerosols, but this gets right to the heart of the terminology issues...
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Replying to @angie_rasmussen @zeynep and
...what's the difference between a < 5 um aerosol vs a slightly larger airborne droplet? Not having good terminology muddies the water and makes it hard to communicate effectively with each other and with the public.
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Replying to @angie_rasmussen @zeynep and
I am not sure our communities really care what you call the airborne particles that they can inhale and possibly get infected. Or what size they are. They want clear consistent guidance on how to reduce risk.
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Replying to @ShellyMBoulder @zeynep and
That's true, and that's what many of us have been providing. I have been advising people of the same risk reduction measures since the spring, including letting people know that inhaled droplets are thought to be a major driver of transmission.
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Replying to @angie_rasmussen @ShellyMBoulder and
This is why the terminology is important, though. This entire issue has been one of communication. Transmission by inhaled droplets/aerosols/particles has been presented to the public as if this is new information when it's not and people are confused about what this means.
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Replying to @angie_rasmussen @ShellyMBoulder and
I am genuinely confused by what you are saying. - WHO talking about ballistic droplets, see video. And "FACT: NOT AIRBORNE". And guidance consistent w/ that, eg STILL NOW masks indoors only if can't keep 1 m distance https://twitter.com/i/status/1244258441880797184 …pic.twitter.com/InVsWjBydp
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Replying to @jljcolorado @angie_rasmussen and
However you seem to say that "transmission by inhaled droplets" (i.e. aerosols) has been known for a while, not new info? - Perhaps internally among researchers? - Also at WHO? Is that why they rec ventilation w/o saying why? Recognize it is real but fear of saying "airborne"?
1 reply 1 retweet 5 likes
Having worked with WHO on this, I concur that they are still only recommending masks indoors *if* one meter distance cannot be maintained in the official guidance, and only recently acknowledged the possibility of any droplet/aerosol may remain "airborne" but stubbornly insist +
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Replying to @zeynep @jljcolorado and
that cases like the choir practice and the Guangzhou restaurant etc. could still be fomite or droplet (which they do mean ballistic action but it's muddled). They also say no cases that demonstrate fomite transmission but they still consider it a key transmission mode. Confusing.
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Replying to @zeynep @jljcolorado and
I see the practical relevance of this confusion because, for example, colleges are preparing to open indoor spaces with masks, hand-sanitizers and distancing but not a lot of discussion, if any, about the importance of ventilation or recognition that 1-2m indoors isn't absolute.
4 replies 0 retweets 14 likes - Show replies
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