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Devabhaktuni
Devabhaktuni "Sri" Srikrishna
@sri_srikrishna
Working on how to stop spread of viruses since 2014. Founder https://t.co/HWrQJSBTiV: N95 + air purifier how-to. MS (EECS). Like, share, or retweet ≠ endorse.
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Feb 27 • 9 tweets • 5 min read
The trusty Temtop PMD 331 is ISO certified but PRICEY ($1399).

Are there cheaper particle counters to test DIY air purifiers that still work well at 0.3 μm or at submicron particle sizes?

Here is what I found.

(1/9)


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Image The Temtop PMD 331 is ISO-certified.

It enables testing performance of DIY and HEPA air purifiers at 0.3 μm using AMBIENT aerosols.

It was necessary to convince the peer-reviewers in my publication (2022).

(2/9)
sciencedirect.com/science/articl…
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Feb 13 • 8 tweets • 3 min read
MERV 16 vs 13: LONG TERM TEST 🏎️

— Summer ☀️ ‘23: 160 SAFE boxes installed in classrooms of middle school 🏫 in SF.

— Mix of 5” MERV 16 and 5” MERV 13 (both Lennox).

— TEST: Filtration💨 at 0.3 μm (%) before vs after 1 semester 📆 daily usage ⏳

Results below.

(1/8) FILTERS CHOSEN FROM CLASSROOMS WITH DAILY USAGE ⏳:

To measure filtration efficiency (%), filters chosen from classrooms where teachers 👩‍🏫🧑‍🏫 self-reported daily usage in survey (Dec ‘23 ❄️).

Fans run 🔄 by teachers during school 🌞 turned off🎚️after school 🌙

(2/8)
Jan 12 • 9 tweets • 3 min read
SAVING FLOORSPACE: after we figured out low-noise air purifiers in 2022-23, surveys of teachers using 3+ SAFE air purifiers per classroom revealed need to take up less floorspace in cramped classrooms 🏫 .

Can stacking them TRIPLE the CADR in same real estate?

(1/8)
Image Three SAFE boxes were needed to get 6 air changes per hour in a classroom at Aptos Middle School in San Francisco.

(2/8)

Jan 5 • 7 tweets • 4 min read
MASSIVE POLLUTION FROM A FROZEN PIZZA 🍕:

Since it is the new year I decided to relax 😎 and try out new brand of thin crust frozen pizza.

But I got totally smoked 🔥 .

(1/7) Image Directions are to place it directly on the center oven rack which I did.

(2/7)
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Dec 8, 2023 • 9 tweets • 2 min read
SURVEY of 18/18 teachers 👩‍🏫 🧑‍🏫 using DIY and HEPA air purifiers 💨 at Commodore-Sloat elementary school 🏫 in San Francisco 🌉:

89% using them DAILY 🕰️

11% using them WEEKLY 📆

(1/8) Why do you USE air purifiers in your classroom?

89% COVID 🦠

89% air circ. ♻️

83% Respiratory viruses besides COVID (e.g. flu) 😷

67% wildfires 🔥

56% air circ. when hot 🥵

50% air pollution 🚭

39% allergies 🤧

17% control odors 💩

11% industrial pollution 🏭

(2/8)
Aug 16, 2023 • 26 tweets • 8 min read
Today, Statnews published my new op-ed on WILDLY 🔥 INACCURATE BP READINGS sometimes with home BP machines. (1/25) statnews.com/2023/08/15/at-… HYPERTENSION is the #1 risk factor for death globally 🌎. It’s no surprise cheap BLOOD 🩸 PRESSURE (BP) MACHINES are in clinics + homes across the US 🇺🇸. “Get It, Slip It, Cuff It, Check It” makes it sound so simple 🤡. (2/25) Image
Aug 13, 2023 • 14 tweets • 4 min read
PARENTS: ARE YOU WORRIED 😟 ABOUT BAD INDOOR AIR QUALITY 💨🤧🔥IN YOUR KID’S SCHOOL?

A step by step guide on how to fix 🛠️it (with a little luck 🍀 🤞)

(1/14) Perhaps you “put the moose 🫎 on the table” in past but unaddressed b/c:

(1) school staff receptive but other things taking priority ✌🏽.

(2) staff opposed to better air quality😡.

(3) staff or district were sold on a bogus air cleaning tech 😍.

2, 3 harder, 1 easier.

(2/14)
Aug 12, 2023 • 23 tweets • 10 min read
CLEAN AIR IN *ALL* CLASSROOMS 🌎: This morning ☀️ I was so excited to address teachers at Aptos middle school (6-8) in SF about 160 DIY air purifiers. Congrats 👏to parents who built, installed 3 of them in ALL CLASSROOMS in summer. Below my notes, Q&A from morning talk. (1/23)

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Image TEACHER QUESTION #1: How long do the filters last? Best data from 1+ year operation at Commodore-Sloat Elementary school 📚 in SF ❤️ is the Lennox MERV 16 filters last over a year subject to ymmv based on environmental conditions 🔥 . (2/23) https://t.co/tBEjPfiSotmedrxiv.org/content/10.110…
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Aug 6, 2023 • 33 tweets • 13 min read
SHOUT OUT to @AirResources and @CAPublicHealth for INSPIRATIONAL leadership 💪 on DIY air cleaners to improve indoor air quality in California 🥑 and beyond. (1/) https://t.co/49V0XyNtJdww2.arb.ca.gov/protecting-you…
Image DIY: Parents 🙋‍♂️💁‍♀️+ school teachers/staff 👩‍🏫 👨‍🏫 are implementing CARB’s idea of BOX FANS + 5” MERV 13-16 FILTERS🌪️ for wildfire smoke + Covid mitigation at an elementary AND middle school in San Francisco ❤️ with @projectn95. (2/)
Jul 30, 2023 • 6 tweets • 3 min read
“Participants who reported a previous COVID-19 infection were 9.7 times as likely to have rapid abdominal aortic aneurysm growth (higher growth than the average of 2.7 mm per year). The average size of the abdominal aorta is 2 cm (0.79 inch).” newsroom.heart.org/news/abdominal… "People who have risk factors for developing abdominal aortic aneurysms, and those already known to have abdominal aortic aneurysms who are having their progression monitored, should know that COVID-19 infection may potentially alter the natural course or outcome of abdominal… twitter.com/i/web/status/1…
Jul 9, 2023 • 25 tweets • 10 min read
3 EASY STEPS TO MAKE YOUR DIRTY 💨 OFFICE AIR SUPER CLEAN 🧼: At my kids’ orthodontist 🦷 they wear surgical masks 😷 + have sign saying “DON’T PASS BY UNTIL YOU SANITIZE..” Yet they didn’t have windows 🪟 open in summer ⛅️ nor do they run air purifiers 🌪️🤷‍♀️🤷🤷‍♂️ (1/25) This is why I wrote up this 2-page “clean air” HOW-TO manual for in businesses with @AbraarKaran and @RanuDhillon (2/25) https://t.co/Y9JN5VqVT0hbr.org/2023/07/making…
Jul 7, 2023 • 18 tweets • 6 min read
TOP 11 REASONS NOT TO CLEAN (SCRUB) 🧽 YOUR INDOOR AIR 🌪️ (not a typo): I get it. There are so many good reasons to maintain the status quo 👌(1/18) #1 YOU LOVE 💕 TO MAKE MISTAKES: Moves by intn’l chess ♟️ players were analyzed with AI by MIT researchers and they found more particulates in the air led to more mistakes. If you like mistakes don’t bother cleaning the air. (2/18)
Jun 30, 2023 • 11 tweets • 3 min read
SAFETY 👷‍♀️👷IS JOB #1 for IAQ 🌪️🏡: In HISTORIC news, on May 12, 2023 the CDC recommended minimum 5 air changes per hour (5 ACH) in *all* occupied spaces. The # of purifiers needed and cost rises proportionally to both room volume and target ACH. (1/11) https://t.co/3rDAMemxhFcdc.gov/coronavirus/20…
ELECTRO-MECHANICAL RISK ⚡️ ⚙️: Since air purifiers are heavy devices that plug 🔌 into AC outlets , ensure safe installation/operation by consulting your local expert for electrical 💡, mechanical ⚙️ , earthquake 🫨 safety esp. with in multiple purifiers in room. (2/11)
May 21, 2023 • 21 tweets • 13 min read
A DREAM 💕 COME TRUE! This is EPIC 🏄‍♀️. TYSM @CDCgov. 5 air changes per hour (5 ACH) 🌪️ is now minimum expected indoors 🏡 wherever humans breathe 🧘‍♀️. Small step🦶for CDC, giant step 🏃‍♀️ for humans. Now work begins to implement it 🇺🇸 🌍. (1/21) cdc.gov/coronavirus/20… Image 5 is a BARE MINIMUM ⌛️ and I would have liked to see 12 ⏳ on passenger airplanes inflight ✈️ but this CDC target is a big step🦶in the right direction. Imagine if this was stated clearly back in 2020. @AbraarKaran @RanuDhillon (2/21) latimes.com/opinion/story/… Image
Feb 27, 2023 • 13 tweets • 4 min read
DEEP ANXIETY😬 ABOUT AIR ☣️ IN CALIFORNIA 🥑 SCHOOLS 🏫:

DAY 1: 30+ RESPONDED to survey (> 75% parents, 5% educators)

DAY 2: 50+ RESPONDED. Answer percentages consistent with DAY 1 in yesterday's thread.

Are we just getting started?

Respondent ANGST in quotes below. Image HVAC:

"No HVAC."

"No info on HVAC system."

"HVAC systems filters are frequently out of date and there's no system to check and replace them"

"HVAC turned off or on auto."

"Our HVAC is so old the district cannot fit merv 13 filters."

(2/12)
Feb 26, 2023 • 11 tweets • 7 min read
CALIFORNIANS 🥑 SPEAKING OUT 🗣️ ON CLASSROOM AIR QUALITY:

In last 24 hours 🕰️ I asked parents, teachers, principals, and other involved with California schools 🏫 to share thoughts on classroom air quality. 30+ responded quickly (75% parents, 10% educators).

Results:

(1/10) 85% SAY CLASSROOM AIR QUALITY IS IMPORTANT (75% v. imp.): Top concerns included respiratory viruses ☣️ (94%), Covid 🦠 (91%), wildfire 🔥 pollution (80%), cognitive 🧠 effects of poor air quality (54%), PM 2.5 ☁️(51%), CO2 💨 (49%).

(2/10)
Feb 19, 2023 • 5 tweets • 2 min read
SMOKING 🚬 vs COOKING 🥘: which is worse?

Most foods didn’t produce a lot of particles on particle counters but some did.

DO NOT TRY. First here is burning cigarette 🚬 at its highest counts. Most of time much lower. Hood on + purifiers on + windows opened + N95. (1/5) Image MICROWAVE POPCORN 🍿 vs CIGARETTE 🚬 : same ballpark. (2/5)
Feb 13, 2023 • 23 tweets • 7 min read
3 “OBJECTS” SHOT DOWN OVER US/CANADA: First time in history NORAD took kinetic action against airborne threat in North America. Why now? What we do know, and not know? Aliens? All explained through transparent Q&A by Pentagon this afternoon. (1/23)
ATTRIBUTION: Unlike Sen. Schumer's attribution to China, General Glen Vanherck (NORAD) said he is hesitant and urges *NOT* to attribute it to any specific country yet, until they get hands on objects and determine where came from. He is not abcnews.go.com/Politics/week-…… twitter.com/i/web/status/1…
Feb 12, 2023 • 4 tweets • 3 min read
HIGH RISK TO ELDERLY REMAINS: One the one hand this NYT article discusses risks of hospitalization 🏥 + death ☠️ from Covid 🦠 for older people remains too high. (1/4) PAXLOVID: One the other hand Paxlovid 💊 is now seen almost as a “miracle drug” in terms of preventing hospitalization + death among older people. “Among patients 65 years of age or older, the rate of hospitalization due to Covid-19 was 14.7 cases per 100,000 person-days among… twitter.com/i/web/status/1…
Feb 9, 2023 • 5 tweets • 2 min read
HORRIFYINGLY ‼️ HIGH PARTICLES FROM ELECTRIC ⚡️ STOVE: After learning “particle physics” in my kitchen, today I installed 2 particle counters ⚖️ in my mom’s kitchen so she too can be aware of toxic ☣️ particles when she cooks 🍳. To my horror, I saw them w/o cooking!! (1/4) Image BURNT STUFF🔥IN THE ELECTRIC STOVE: There was burnt junk 🌮 in her electric stove (spilled butter 🧈 etc). When electric stove turned on w/o food it smokes invisibly 👻 not enough to trigger smoke alarm. Video (4x speed) shows counts rose at ~ 30s, off scale (999) by ~60s. (2/4)
Jan 27, 2023 • 12 tweets • 5 min read
BURNING BUTTER 🧈 ON STEEL PAN 🍳: (4/15) CONFIRMED by @CRBoxKits: Even his updated range hood was not enough. Tysm for doing this experiment 🔬 and reporting the results! (5/15)