1/ Thank you, Dr. @lisa_iannattone, and right on! And as an environmental engineer I never learned about physiology, internal organ function, etc. The best scenario is when we all work and learn form one another. That's the way we take on big challenges effectively. 👇👇👇👇
2/ Many years ago I was a PI on an NSF IGERT grant that involved students across 6 colleges at UT Austin. They wrote a wonderful editorial about the importance of interdisciplinary collaboration. onlinelibrary.wiley.com/doi/full/10.11…
3/ The last paragraph in their editorial is particularly relevant.
4/ A few years later I wrote this editorial about the lack of innovation that stems from scholars staying in their own intellectual trenches (this followed a closing plenary that I gave on the same topic at Indoor Air 2014 in Hong Kong).
5/ Whether deadly pandemics or climate change, major challenges require those from different disciplines to collaborate and not engage in combat, to put minds together and not to practice isolation. That's how we collectively solve and overcome.
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1/ Automobiles and Intake Fraction. Since cars are back in the news I thought I would retweet this model result I offered in early April 2020. I focused only on 1 micron particles & accounted for windows completely closed & cracked slightly open.
2/ Related air exchange rates were based on experimental results in literature for mid-sized sedans. Particle deposition to indoor surfaces were accounted for, as the surface to volume ratio in a 3 m3 cab is large. An important outcome was the intake fraction (IF)
3/ Here, IF is the number of particles (or virions in collective particles) inhaled by a receptor DIVIDED BY the number or particles (or virions in collective particles) emitted by an infector.
Total US COVID-19 deaths = 385K (400K by end of weekend)
1 of every 855 Americans dead by COVID-19
1 of every 43,600 S. Koreans dead by COVID-19
End of Feb 2020
US deaths = 20
South Korean deaths = 17
By end of Feb 2021 US likely exceeds 500K
S. Korea may exceed 1,400
2/ Yes, the vaccine will ultimately help. But unless we work relentlessly to starve this virus of its hosts the case and death count will remain out of control until then. And the new variant means that we need to quadruple down on reducing inhalation dose.
3/ Inhaled dose (D) is important in BOTH the near (close) and far fields.
D = C x B x t x f
D = # virus-laden particles deposited (ultimately convert to vol), C = concentration in breathing zone (#/L), B = resp minute volume (L/min), t = time (min), f = fraction deposited.
US = 1 out of every 862 Americans dead by COVID-19
S. Korea = 1 out of every 46,000 dead by COVID-19
By end of Feb 2020 the US deaths by COVID-19 = 20
By end of Feb 2020 we will likely exceed 0.5 million
Despite an extraordinary time frame for an effective vaccine, things will continue to get worse until widespread vaccination occurs if Americans continue to fail to accept and relentlessly employ layered inhalation dose reduction. It's not rocket science, folks.
See my previous twitter threads as well as those of others. Explore here: safeairspaces.com. A blog on inhaled deposited dose and key factors here: corsiaq.com.
Particle settling: In case anyone wants to see a derivation of Stokes equation for particle settling - here is one of my old course notes. Note that aerosol particles achieve terminal settling velocity almost instantaneously, unlike someone jumping out of an airplane. more ...
This derivation assumes spherical particles & does not adjust for different shapes that affect drag force. It also does not adjust for particle "slip" as diameter approaches the mean free path of air molecules & drag is reduced as the no slip condition is violated. more ...
A 0.1 micron particle settles three times faster for this reason than is shown at the bottom off the page. A 1 micron particle settles about 17% faster. Slip correction becomes smaller and smaller for larger particles. More ....
1/ Dealing with an inferno of infectiousness.
We failed to do what was needed to keep this mess from getting out of control. Our situation is horrific and will soon get much worse due to end-of-year holidays + more infectious variant. Vaccine distribution also F grade to date.
2/ All of this means even greater mass casualties (for both those who live and die) in the coming months.
3/ Expect one-half million dead by end of February, a lot more of the following: refrigerated trucks outside of hospitals, hospitals faced with triage, schools that will not re-open, business closures, lost jobs, homeless, and (unfortunately) more.
I taught both undergraduate and graduate indoor air quality classes for many yrs at UT Austin. Proud of the fact that many current professors (and some department chairs) took my courses as students & are now teaching a new generation.
2/ I loved infusing my research into lectures, having students bring different scented products to the classroom, exposing them to a small amount of ozone and measuring ultrafine particle formation (image). We also measured rebreathed fraction in the classroom, etc.
3/ Every class would have an assignment with CO2 analyzers checked out to groups w/ 1 wk to measure avg CO2 concentrations and rebreathed fraction & then use the Rudnick-Milton model to estimate probability of common cold & flu transmissions across campus (50+ locations/class)