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Dr. Alex Huffman Profile picture
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13 Jan, 5 tweets, 4 min read
1/ Really great article that explains common misconceptions & myths about airborne viruses. Clear & easily readable.

Led by a #multidisciplinary slew of all-star scientists. If you trust anyone in the world on these topics, these are the people you trust.
journalofhospitalinfection.com/article/S0195-…
2/ Dispelled myths:

Myth 1: #Aerosols are droplets with a diameter < 5 μm
Myth 2: All particles > 5 μm fall within 1-2 m of the source
Myth 3: If it's short range, then it can't be airborne
Myth 4: If R0 isn't as large as for #measles, then it can't be airborne
3/ Dispelled myths:

Myth 5a: If it's #airborne then surgical #masks (or cloth face coverings) won't work
Myth 5b: The virus is only 100 nm (0.1 μm) in size so filters and masks won't work
Myth 6: Unless it grows in tissue culture, it's not infectious

#COVIDisAirborne
4/ Read & share the paper to better understand airborne transmission of COVID.

Excellent group of authors on the paper, including:

Dr. Julian Tang et al.
@WBahnfleth
@jljcolorado
@ShellyMBoulder
@linseymarr
@WargockiPawel
(and many others not on Twitter)
doi.org/10.1016/j.jhin…
Article 👆 HT @PrasadKasibhat1

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More from @HuffmanLabDU

Dr. Alex Huffman Profile picture
15 Jan
Important new preprint from Lednicky et al. on #aerosol transmission of COVID

*Aerosol <0.25 - 10 μm collected in car driven by COVID-patient w/ mild symptoms
*Viable virus only detected in airborne particles in size range 0.25 – 0.5 μm

HT @DavidElfstrom
medrxiv.org/content/10.110…
Paper shows: "the potential risk of SARS-CoV-2 transmission by minimally symptomatic persons in the closed space inside of a car (w/ closed windows & air conditioning running), & suggest that a substantial component of that risk is via aerosolized virus."
medrxiv.org/content/10.110…
This 👇 earlier paper by the same Lednicky et al. (published Sept. 2020) showed viable (infectious) SARS-CoV-2 was present in aerosols within the hospital room of COVID-19 patients.

Both add to growing body of evidence of real-world COVID #aerosol risk.
ijidonline.com/article/S1201-…
Read 7 tweets
Dr. Alex Huffman Profile picture
15 Jan
1/ Adding #ventilation helps reduce (but not remove!) aerosols & risk from COVID. One simple measure of ventilation is to keep #CO2 sufficiently low. Simple CO2 sensors can be <$150 and are easy to take with you.

One nice summary of consumer CO2 monitors:
bit.ly/monitorsCO2
2/ The idea is that indoor #CO2 comes primarily from people breathing out; but breathing also produces potentially infectious aerosols. So keeping #CO2 levels <800 ppm (or <600 ppm) means air is likely refreshed rapidly enough to keep aerosol risk low.
Image
3/ There are lots of good resources & articles on improving #ventilation & for using #CO2 monitors for rough checks. This article by @B_resnick from months ago is worth a read as a broad overview on various topics related to air safety wrt COVID/aerosols.
vox.com/science-and-he…
Read 8 tweets
Dr. Alex Huffman Profile picture
17 Dec 20
1/ During July 2020 many worked quickly to scramble #COVID19 prep before the Fall classes. I helped model estimated COVID #aerosol risk as @UofDenver made plans. Not allowed then, but shared now in case it can prompt discussion for Winter prep.

Doc + 🧵:
bit.ly/3gVfMcu
2/ A key concern at the time (& still) was #music ensemble classroom activities, b/c it was obvious early on that #COVIDisAirborne and that #choir & wind instruments were likely to present high COVID #aerosol risk.

nfhs.org/articles/unpre…
3/ Using my version of an aerosol #boxmodel, I calculated probability that #SARSCoV2 could infect after breathed out by someone in specific classrooms. With this I could easily investigate best prevention bang for buck. I.e. Rehearsal duration? Wait time b/n classes? Etc.
Read 20 tweets
Dr. Alex Huffman Profile picture
17 Nov 20
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…
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
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
Read 14 tweets
Dr. Alex Huffman Profile picture
15 Nov 20
1/ Apparently #OSHA has updated guidance on #ventilation in the workplace wrt to #COVID19 prevention. See thread 👇by @AliNouriPhD.

BUT ... I looked into their explanations on how SARS-CoV-2 is spread & precautions. Their statements are woefully insufficient or inaccurate.
2/ Specific OSHA guidance on ventilation is weak, but okay. Tho "Ensure all HVAC systems are fully functional" or "Upgrade to MERV 13 or higher filters where feasible" isn't exactly ground-breaking at this point.

Direct doc link (no post date, but today?)
osha.gov/Publications/O…
3/ More shocking to me is that the #OSHA summary of "How does COVID-19 spread?" reflects all sorts of inaccurate or unclear statements that were never true & that most agencies eventually expunged long ago.
Read 8 tweets
Dr. Alex Huffman Profile picture
14 Sep 20
At least five great webinars / learning opportunities on airborne COVID & aerosols this week. See Tab 7 (Live Webinars) here for links & previous webinars/recordings: bit.ly/3fzmB16; links for this week in thread.
[Let me know if I’ve missed any]
(1/4)
Webinars this week including (all times Eastern):
Today (9/14: <1 hr from now): Dr. Lidia Morawksa & @j_g_allen
(Aerosols & school re-opening)

9/15 (2pm): @linseymarr
(Research into airborne transmission of inf. disease)
(2/4)
Webinars this week including (all times Eastern):
9/15 (2pm): @jljcolorado
(Minimizing airborne transmission of COVID indoors)

9/17 (11:30am): @Smogdr
(Mask Design 101: A bootcamp for personal coverings during COVID-19)
(3/4)
Read 5 tweets

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