1/x With #COVID19 cases skyrocketing all over the US, holiday meals are going to be very dangerous. To show the risks of meeting indoors I used an #aerosol box model to estimate relative the risks.
Maybe this can help you re-think your plans to gather.
drive.google.com/file/d/1xmN0e4…
Maybe this can help you re-think your plans to gather.
drive.google.com/file/d/1xmN0e4…
2/x The #WellsRiley model has been used for decades, was put online recently by @jljcolorado & others as a #COVID19 viral aerosol transmission tool. In July I re-wrote the model onto a different platform @Wavemetrics #IgorPro so I could manipulate faster.
tinyurl.com/covid-estimator
tinyurl.com/covid-estimator
3/x Modeled only room-mixed #aerosol (not droplet spray or aerosol plume; these add risk).
Results highlights:
- No matter the room size, infection for 10 people is at least 40% or much more
- If #superspreader there, everyone will be infected
- Outside, risk drops dramatically
Results highlights:
- No matter the room size, infection for 10 people is at least 40% or much more
- If #superspreader there, everyone will be infected
- Outside, risk drops dramatically
4/x - As expected, the simple model shows ventilation matters and adding a HEPA filter unit to a fairly small dining room drops risk by as much as 3x.
- Opening windows can help a lot too.
See e.g. tinyurl.com/portableaircle… by @ShellyMBoulder @j_g_allen @cedenolaurent for more.
- Opening windows can help a lot too.
See e.g. tinyurl.com/portableaircle… by @ShellyMBoulder @j_g_allen @cedenolaurent for more.
5/x – Monitoring carbon dioxide (rough proxy for exhaled breath) can be related to aerosol risk (varies)
- Depending on room size, one modeled relationship between CO2 and aerosol risk below
- See e.g. tinyurl.com/FAQ-aerosols for (Sect. 9) ideas to monitor #COVIDCO2 for <$150
- Depending on room size, one modeled relationship between CO2 and aerosol risk below
- See e.g. tinyurl.com/FAQ-aerosols for (Sect. 9) ideas to monitor #COVIDCO2 for <$150
6/x Summary of #COVID19 #aerosol modeling:
There is *significant* risk by meeting indoors for holiday meal. Largely b/c no #masks during eating and drinking. With a 10-guest gathering, very possible someone will be infected. If #superspreader, everyone will be infected!
There is *significant* risk by meeting indoors for holiday meal. Largely b/c no #masks during eating and drinking. With a 10-guest gathering, very possible someone will be infected. If #superspreader, everyone will be infected!
7/x Risk modeled here is *only* for room-mixed #aerosol. Total risk much higher (challenging, but maybe several times), because droplet spray and nearby aerosol plume could be dominant from close sources (at a table). This is the focus of CDC & WHO.
cdc.gov/coronavirus/20…
cdc.gov/coronavirus/20…
8/x Other details here, in doc; you can see specific risk relationships by reducing gathering time, number of guests, adding #filtration, #ventilation, etc.
Summary - Far best simply to *avoid* gathering indoors this year for #Thanksgiving. #COVID19 is just too dangerous atm.
Summary - Far best simply to *avoid* gathering indoors this year for #Thanksgiving. #COVID19 is just too dangerous atm.
9/x Details: Model version checked against online tool. Base assumptions: 10 guests, 2 hr, 2.5% inf rate, 80 q/hr inf emission (see doc).
Numerical assumptions can be challenged; happy to discuss, improve. Point was to offer quickly for discussion wrt Thanksgiving #COVID risk.
Numerical assumptions can be challenged; happy to discuss, improve. Point was to offer quickly for discussion wrt Thanksgiving #COVID risk.
10/x Other aerosol models so you can estimate specifics of your own holiday gatherings:
tinyurl.com/covid-estimator by @jljcolorado
…re-modeler-data-devils.cloud.duke.edu// by @PrasadKasibhat1 et al.
safeairspaces.com/safeairspaces-… by @Wymelenberg et al.
nationalgeographic.com/science/2020/0…
tinyurl.com/covid-estimator by @jljcolorado
…re-modeler-data-devils.cloud.duke.edu// by @PrasadKasibhat1 et al.
safeairspaces.com/safeairspaces-… by @Wymelenberg et al.
nationalgeographic.com/science/2020/0…
https://twitter.com/Wymelenberg/status/1305926152851091456
11/x Many good recent resources on risks, especially including restaurants and bars. These suggest same reasons as for holiday meals: no masks, closed spaces, mixed households, loud talking, (alcohol).
https://twitter.com/Prof_Lowe/status/1328718007099674627by @Prof_Lowe
https://twitter.com/HuffmanLabDU/status/1326565694083788800
12/x Good additional links to give some ideas about Thanksgiving:
Threads by @kprather88
and @DearPandemic
scientificamerican.com/article/how-to…
nytimes.com/2020/11/06/wel… by @taraparkerpope
Threads by @kprather88
https://twitter.com/kprather88/status/1328009204754333701
and @DearPandemic
https://twitter.com/DearPandemic/status/1328355145428635651
https://twitter.com/carlzimmer/status/1327790189004136449
https://twitter.com/AmerMedicalAssn/status/1326937172604280836
scientificamerican.com/article/how-to…
nytimes.com/2020/11/06/wel… by @taraparkerpope
13/x Through all of this, layered prevention is absolutely key. But YOU can control your #mask, #socialdistance, shared time #indoors and choose places with adequate #ventilation. This is why restaurant and holiday meals are so risky.
https://twitter.com/MackayIM/status/1319901144836026368
14/x For more resources on #aerosols and #airborne spread of the pandemic as you make holiday or #Thanksgiving plans, peruse articles and lots of other resources on #transmission and #prevention of #COVID19 here: bit.ly/3fzmB16
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