I’ve been looking for a good analogy to airborne vs sprayborne, and asked all the experts, and this may yet be the best (for people who go to hair salons!)
This matters, because having the correct mental model can empower people to think through this.https://twitter.com/tressiemcphd/status/1289602987711582208 …
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Short answer: Hepa filters with no gimmicks (ionizer, UV) are good for unventilated spaces. Higher CADR (smoke rating) is better. If you can open windows/doors for good air circulation, better. Better answer: follow
@jljcolorado@ShellyMBoulder@kprather88https://twitter.com/__apf__/status/1292085934767316997 …Show this thread -
Thread below with some answers. Also more experts to follow:
@linseymarr,@corsiaq,@JimRosenthal4,@stephensbrent. That said, it's past time for CDC to step up and give us guidance on ventilation. As I wrote, Japan has been doing that since the beginning.https://twitter.com/jljcolorado/status/1291760621822726145 …Show this thread -
The dearth of communication from health authorities on even the most basic questions like the one below is maddening. The few experts on social media are doing what they can, but it's really time for the academy to form it's own shadow CDC to communicate.https://twitter.com/zeynep/status/1291777886014365696 …
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Same dynamics that led to misrepresentation of mask research early on—ignoring evidence (a-presymptomatic spread), making baseless claims (false sense of security/harm), treating the public like children, lack of clarity on evidence to action etc. are in-play with ventilation.
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"More research is needed." Yep, as usual. Just like with masks in March, there's a preponderance of evidence to act on ventilation. The answer to shortages was to treat the public as a partner & adults who deserve information; the answer to "don't scare the public" is.. the same.
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FWIW, the reason I got into ventilation/short-range aerosol research was what I heard from *epidemiologists* first who decisively argued that that epi data was the strongest reason to suspect this mode of transmission. This isn't a US-only conversation!https://twitter.com/B_resnick/status/1293934375009165312 …
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That engineers are arguing for aerosol transmission while Epi/ID folks are against works only if one cherry-picks examples plus ignores countries with top-notch experts and solid track record outside the US/EU. Even here, despite disagreements, the consensus/overlap isn't small.
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This week, the WHO is holding a "wear-a-mask" challenge and our outlets are writing a "how did the WHO/US/CDC/UK/EU/media got it so wrong" articles. How about we do better this time and practice evidence-based causal inference and communication that treats the public like adults?
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Honestly, the idea that there's some sort of engineers vs. epidemiologists/infectious-disease specialists divide on airborne/aerosol transmission is just not true the moment you step out into the world. Japan, Hong Kong, South Korea, Taiwan.. US is just behind, again, that's all.
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This is why this "debate" matters. This isn't safe even if people are distanced (WHO says 3 feet and CDC says 6 feet is enough!!) exactly because short-range aerosols and their accumulation indoors, not just droplets that immediately fall, is a concern.https://twitter.com/trishgreenhalgh/status/1293826751844450304?s=20 …
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Why getting airborne right matters. UNC has clusters. (Surprise? No). They're contact tracing for within six feet without masks. NOT ENOUGH FOR INDOORS. Distance isn't that protective indoors *and* source-control masks aren't magic. We need updated evidence-based guidelines ASAP.pic.twitter.com/ob2zTSVALa
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The cost of not explaining the mode of transmission and risks correctly. This is simply not protective enough indoors, and CDC and the WHO need to urgently update their guidelines. (Look at that window that's being ignored!) https://twitter.com/ProfChrisMJones/status/1293909582692007936 …
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(Also, the answer to the terminology issues is to use the terms people will use—yes, airborne—with ample description and visuals. Linguistics teaches us that we cannot prescriptively do away with people's words, and if we try, what we will get is misunderstanding misinformation.)
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Other countries have managed to communicate this well, we can too. Japanese epidemiologists told me they suspected aerosols early on because of transmission data and acted accordingly—and have had a stellar public communication strategy. We should repeat. https://twitter.com/dylanhmorris/status/1294829604167876613 …
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Remember the "people will not be able to wear masks correctly" or "they will have false sense of security" claims as obstacles to recommending masks even though other countries managed just fine? Let's not do this again. We can communicate with the public, just like others do.
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Alternative to communicating the correct & detailed mental models to the public is rigid, rule-based but ineffective behavior. The problem isn't just terms—which cannot be dictated if there is an everyday word: it's insufficient effort in explaining them.https://twitter.com/JuliaLMarcus/status/1294784174616961025 …
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Stellar example of effective science communication from
@JamesEKHildreth who clearly but matter-of-factly explains a latest key paper on aerosol transmission, and why, by itself, distance isn't all protective indoors—especially in low ventilation settings.https://twitter.com/i/status/1294947678011502592 …
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Excellent FAQ for use of HEPA filters in indoor environments. Keep in mind: mitigations stack and every layer helps reduce risk. Masks. Distance. Effective filters (HEPA). Ventilation. Reduce crowding. Less talking. Keep within a cohort. etc. All adds up.https://twitter.com/Poppendieck/status/1292433631743561729 …
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Fascinating thread from an aerosol scientist, also talking of a forthcoming preprint exploring a compelling case I heard from multiple scientists about a major scientific error by WHO in their transmission mode documents. These details aren't minor issues.https://twitter.com/jljcolorado/status/1295524565179748352 …
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Germany (and some other European countries) are rapidly moving to acknowledge the importance of ventilation and updating their advice. It's way way way past time for the WHO and CDC to update us with proper guidance, beyond broad generalities.https://twitter.com/jljcolorado/status/1296251453296664576 …
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Merging some threads here! Please go read this very interesting article by
@jljcolorado, but please don't look at the picture! (Link to article in next tweet).https://twitter.com/zeynep/status/1299365652982124550 …
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Here's the article by
@jljcolorado that compiles a lot of evidence about aerosol transmission playing a role for COVID, with practical takeaways. (I genuinely don't know what it will take for news media to stop with the obsession with outdoor pictures.)https://time.com/5883081/covid-19-transmitted-aerosols/ …Show this thread -
"Because of the remarkable increase of COVID-19 infections in a very short time period despite the use of surgical masks, the ventilation system of the outbreak ward was investigated in addition to routine source and contact tracing" Ventilation study: https://twitter.com/linseymarr/status/1300782502550876161 …
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Also important, by
@DKThomp. Some activities are worse than others: talking, singing, huffing and puffing. We should learn from countries that have guidelines for indoors (library rules: keep it low!)https://www.theatlantic.com/ideas/archive/2020/08/wear-your-mask-and-stop-talking/615796/ …Show this thread -
Consequences of lack of proper guidance on ventilation. This restaurant has blocked *outdoor tables* with plants as per NC guidance, but has reduced seating inside. Everyone should be outside! These tables are far enough.(Place is otherwise well-organized; staff all masked etc.)pic.twitter.com/sG4JRekJQq
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CDC? WHO? We still don’t have ventilation integrated into our guidelines. People are being told to wash their hands, but not open their windows. It’s September 2020.https://twitter.com/adamhamdy/status/1304120806943928329 …
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UPDATE! CDC has *finally* explicitly acknowledged the role of aerosols, airborne transmission and the importance of ventilation for COVID. Now urgently waiting for specific guidelines. (Japan had them since February!) Woot! (Hopefully, WHO soon as well). https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/how-covid-spreads.html …pic.twitter.com/btHcplh34w
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Weekend update, CDC has finally explicitly acknowledged airborne transmission, and is now highlighting the importance of inhalation as a route, and thus ventilation as mitigation. See thread for interesting science history of how key measures got mangled.https://twitter.com/jljcolorado/status/1307920120203759616 …
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Some experts on here say this isn't a major update. I totally disagree. The experts may have already been in the know. General public? Businesses? Schools? Still a lot of bleaching surfaces while not even opening windows. Finally, the science is reflected.https://twitter.com/jessica_bassett/status/1308022681732886529 …
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Yes. Updated CDC guidelines acknowledging airborne transmission and inhalation as key route have *huge* implications for both masking guidelines & indoor behavior—before we even get to additional ventilation mitigation. Details is in my article upthread.https://twitter.com/HikerDave57/status/1308025529472151554 …
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Tradition > technobabble.
No I can't endorse products.

Thrilled to see the message about the importance of ventilation *finally* breaking through to the broader public (at least, I hope so!). (Sane policies for/media coverage of the safer activities outdoors, maybe, too, one can hope?)