Read on Twitter
Let's #UnPack (some facts) before we #FlyAgain. Lots of threads lately about if it is #Safe2Fly & how to #FlySafe. Here are a couple with really good information.
This article by @ernstkc & @BeamerPaloma provides good guidance to #MinimizeRisks. Great ideas for #HandHygiene 
while travelling, pick a #WindowSeat to minimize 6' sphere exposure, beware of neighbors #droplets. https://theconversation.com/should-you-fly-yet-an-epidemiologist-and-an-exposure-scientist-walk-you-through-the-decision-process-138782?utm_source=twitter&utm_medium=bylinetwitterbutton
while travelling, pick a #WindowSeat to minimize 6' sphere exposure, beware of neighbors #droplets. https://theconversation.com/should-you-fly-yet-an-epidemiologist-and-an-exposure-scientist-walk-you-through-the-decision-process-138782?utm_source=twitter&utm_medium=bylinetwitterbutton
@j_g_allen does a great job explaining hierarch of control to reduce risks, encouraging masks, discusses other risks besides the flight while traveling. Importantly, encourages airlines to deploy gate #ventilation since ventilation is poor at taxi & gate. https://www.washingtonpost.com/opinions/2020/05/18/airplanes-dont-make-you-sick-really/
The article cites this simulation study below. Excerpts: "Expected incidence was low to moderate, with the central 95% ranging from 10(−6) to 10(−1) per 169 passengers in the four scenarios." Lending some confidence. https://onlinelibrary.wiley.com/doi/epdf/10.1111/j.1539-6924.2008.01161.x
However, the paper abstract continues: "Emission rates used were low compared to measurements from active TB patients in wards, thus a “superspreader” emitting 44 quanta/h could produce 6.2 cases or more under these scenarios." Suggesting substantial risk.
Both stories note the 99.97% effectiveness of #HEPA filters to remove particles at 0.3 micron (even better at other sizes); high air changes per hour (10-12 #ACH), and the @ConversationUS piece mentions high outside air (OSA) fraction. Best I can find suggests about 50% #OSA.
The @washingtonpost piece also notes that even sneezes and coughs tend to be minimized to about 2-3 rows of total exposure due to ventilation design. Still a concern (see simulation), but maybe less than many expect.
OK, so here is what I think is missing. First: 10-12 ACH at 50% OSA with HEPA filtration is very good, but not perfect. The minimal infective viral exposure is not known, but it could be very low, and we know that long duration exposure definitely increases risk.
Second: 10-12 ACH 50% OSA + HEPA does not protect you from the 6-18+ people that might be infected sitting in your row, or that just in front/behind. Don't take it from me, let @RM_Wang explain. He is working on some cool #technology for #SaferAir.
Third: Airplanes do not deliver 10 times as much fresh air as an office. Occupant density matters for ventilation. We must consider cubic feet per minute #CFM per person. A full airplane likely has half as much fresh air per person as an office. https://medium.com/science-and-technology/what-we-breathe-when-we-fly-e8eb910d8b48
Fourth: There is #evidence on both sides of the ledger regarding #viral #transmission on airplanes. You can paint the story however you like with citations. Here are a few.
Suggestive against viral transmission on airplanes: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3320400/
And one in preprint regarding a #SARS_CoV_2 airplane outbreak: https://www.medrxiv.org/content/10.1101/2020.03.28.20040097v1.full.pdf
If you are trying to decide on #AirTravel, I hope this was helpful. As for me: I am going to stay #UnPacked for a while longer. And if you want collaborate on this technology, let me know. Why can't we have a mask to directly tap that 10-12 ACH 50% OSA + $HEPA filtered air?
