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Nora Traviss Profile picture
@NoraTraviss
Jul 15, 2018 • 3 tweets • 2 min read • Read on X
Yes, I’m so happy to make bigger point and I know someday teens will appreciate the “live biology” lesson! Lots of fun crab and lobster catching and releasing #invertebratesaresexytoo
Teens are impressed! Success! #biologistsintraining #exploring Except when I explained about Chordata my son instantly broke into “Hakuna matata” from The Lion King. #smallvictories Image
Thank you 😊 @karencang 😘

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More from @NoraTraviss

Nora Traviss Profile picture
Aug 8, 2020
Thread: so in this thread I am posting my results from a "chamber study" at the rural school I described in my earlier thread. Different room, smaller, no air flow. I used a Dylos DC 1100 and a TSI CPC 3007. The CPC is a much better instrument - picks up nanometer particles.
I basically used the smoke kits, 6 puffs, checked instruments after 10 seconds, wrote down "inlet" concentration and then put instruments on "clean" side of fan, about 1/2" from fan about 2 mins later. These are GRAB samples, so spot checks. Very quick and dirty!
Again, here is chicken scratch. Basically about a 23% to 50% reduction in smoke particles, depending on instrument. CPC results (~50% reduction) are more reliable. Other researchers have gotten up to 87% reduction in more controlled settings. Image
Read 4 tweets
Nora Traviss Profile picture
Aug 8, 2020
So I worked with a local school, rural area, NO HVAC, to check out natural ventilation, and setting up box fan configurations and [box fan + 20"x 20" x 1" filter combos]

Smoke Test - before, minimal ventilation, 800 ft2 classroom via @YouTube
I was really surprised with how the smoke just instantly rose just like those animations we have been seeing from aerosol scientists! We had a fan as an exhaust, so some air flow, but clearly not enough!
Then we moved the fans around and settled on this configuration which I have sketched by hand, in terrible chicken scratch, but time is of essence, not art. We settled on a cross flow ventilation, 1 fan as supply in window, 1 as exhaust, w/"box fan +filter" combo in the front. Image
Read 8 tweets
Nora Traviss Profile picture
Jul 3, 2020
Thread: So I’m a Jill of All Trades Scientist - doer of many things and master of none. But I measure particles in air most times. I broke out a textbook Exposure Analysis by Ott, Steinmann, Wallace. A virus is a very tiny particle so what if we treated it as such? 1/
2/ A tiny particle that weighs very little (an attogram according to Wikipedia 1 x 10^-18 of a gram) but still let’s assume the tiny mass is conserved (unlike particle number). With these and some “rule of thumb” or “back of the envelope” assumptions of the equation below: Image
3/then we can determine the max indoor air concentration of virus with some baseline assumptions. 1 person is an emitter in a 30x 40x 10ft class [~340 m^3]. A shedder if you will that emits 600 virus/particles per min while talking. Then the concentration in the room after ...
Read 13 tweets

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