So proud of @KeeneState_ student @CollinCoviello presenting yesterday at #NHINBRE conference. Here he explains our project comparing CYP1A1 mRNA expression (a sensitive biomarker for inflammation) in human lung cells exposed to biodiesel v diesel combustion particles #biodiesel
Why care? Diesel exhaust is well studied and exposure has negative health effects like asthma, cardiovascular inflammation and even lung cancer.
Our lab has shown biodiesel produces far less soot and biodiesel particles kill less lung cells 👍 but lots of questions remain on inflammatory effects. @KeeneState_ is searching for answers to these questions! #STEM#biodiesel
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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.
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.
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:
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 ...