Share this page!

Enter URL or ID to Unroll

You can paste full URL like: https://x.com/threadreaderapp/status/1644127596119195649
or just the ID like: 1644127596119195649

How to get URL link on X (Twitter) App

  1. On the Twitter thread, click on or icon on the bottom
  2. Click again on or Share Via icon
  3. Click on Copy Link to Tweet
  4. Paste it above and click "Unroll Thread"!
  5. More info at Twitter Help
Devabhaktuni
@sri_srikrishna
Jan 17 • 10 tweets • 3 min read • Read on X
BIG NEWS: Yesterday California public health 🥑 just recommended to at least 5 air changes per hour in ALL ROOMS (occupied). Seismic. 🌎

Not just classrooms, but also evacuation centers, offices, homes, too. In agreement with CDC (May, 2023)
“Given all of this information, CDPH is currently aligned with CDC and experts in recommending a minimum of 5 air changes per hour or 30 CFM/occupant of equivalent clean airflow, whichever is greater, in occupied indoor environments.”

cdph.ca.gov/Programs/CID/D…
Why now?

LA fires 🔥 brought this issue to a head.
Last week, volunteers were up all night trying to hand out N95 in evacuation shelters, in some cases expired N95 donated from as far as Texas (from @larmbrust).
CDPH observed that viruses spread in shelters and correctly advises using a high quality mask. This is very welcome to alert people to the risks of congregating in shelters.
N95 has not been scalable in shelters because (1) last week there had been no government supply of N95 in evacuation shelters and (2) people cannot wear masks 24x7.
Volunteers are now setting up DIY air purifiers in shelters because it is more scalable to clean the air indoors than keep using masks all the time.
Air filtration doesn't work unless there is enough of it. If it is too little then then it is not effective.
Just as CDPH did with school classrooms in November 2024, yesterday CDPH provided clear minimum requirements for indoor air cleaning of disaster shelters and homes, stated clearly and precisely by CDPH in an actionable way.
cdph.ca.gov/Programs/CID/D…
x.com/lieslmcconchie… x.com/lieslmcconchie…

• • •

Missing some Tweet in this thread? You can try to force a refresh
　

Keep Current with Devabhaktuni "Sri" Srikrishna

Devabhaktuni

Stay in touch and get notified when new unrolls are available from this author!

Read all threads

This Thread may be Removed Anytime!

PDF

Twitter may remove this content at anytime! Save it as PDF for later use!

Try unrolling a thread yourself!

how to unroll video
  1. Follow @ThreadReaderApp to mention us!

  2. From a Twitter thread mention us with a keyword "unroll"
@threadreaderapp unroll

Practice here first or read more on our help page!

More from @sri_srikrishna

Devabhaktuni
Jan 19
Good q. If it smells toxic or VOC is a concern downwind of wildfires 🔥, below are 3 steps to protect from VOC in order of increasing cost $$.

@717imo @rockncasserole @StevenMathern
VOC Step #1: As an upgrade from N95, P100 respirators with VOC cartridges like this one from GVS, also 3M and others can protect from chemical vapors. amazon.com/GVS-SPR485-Eli…
@PPEtoheros put together a comprehensive explainer on P100 respirators with VOC protection added
Read 22 tweets
Devabhaktuni
Jan 18
Caltech: “…preliminary data from particulate samplers located in Pico Rivera, south of Caltech's campus in Pasadena show significant amounts of both chlorine (from burning plastics like PVC) and lead in the air. (These samplers do not measure asbestos.)”
“In addition to particulate, smoke contains a huge diversity of volatile organic compounds (VOCs). These are the source of much of what we are smelling in the air now.”
“Our homes, apartments, and offices may continue to smell of smoke for a month or more. Homes have lots of porous surfaces (and carpets/rugs), and semi-volatile compounds end up accumulating in these materials.”
Read 7 tweets
Devabhaktuni
Jan 12
“That air that’s being spewed is no longer just the kind of smoke that we used to see from wildfires, where it was natural vegetation that was burning,” said Becerra, a former California Attorney General. “Now you got a whole bunch of toxic materials that are getting burned and put into the air.”
“It’s just a toxic soup,” Lisa Miller, a wildfire smoke expert at the University of California, Davis told NPR. “Think of all the synthetic fibers that are present in your living room—in your couch, in your carpet, in your clothes. All those things can be particularly toxic,” she said.
Link fortune.com/well/article/c…
Read 6 tweets
Devabhaktuni
Dec 29, 2024
Clear explanation of CO2 vs ACH vs viral emissions in room by @ukhadds:

1. CO2 tracks occupant breathing (b/c ~4% of exhaled is CO2), but only indirectly tracks infector viral emission depending on if infector is there, how active (e.g. speaking, working out), and if masking.
2. CO2 can be used to estimate the air changes per hour (ACH) from ventilation only but not from air filtration (such as on airplanes). Air filtration reduces SARS-CoV-2 risk by removing aerosols but without decreasing CO2. Image
3. However higher CO2 lowers acidity of exhaled aerosols and extends % of SARS-CoV-2 in air remaining infectious over time potentially needing slightly higher filtration rate to compensate for extra risk versus equivalent rate of outdoor ventilation (eACH). By how much? Unclear. Image
Image
Read 5 tweets
Devabhaktuni
Dec 15, 2024
Few days ago I met a gentleman in a bar who asked me "why are you still wearing a mask (N95)", insisting "I'm not judging just trying to understand" but after I explained why (covid tx risks), he asked "why" repeatedly and said "that is crazy."

What is the best way to respond?
Covid can be life threatening and it recently killed a physically fit, otherwise healthy friend of mine while he was undergoing cancer treatment. @michael_hoerger @anchari mercurynews.com/obituaries/jim…
To that the man in the bar said “Covid is like the flu”. Dr. Redfield (former CDC director) in interview by @danaparish said Covid is not like flu, it is cardiovascular disease due ACE2 receptors in blood vessels causing strokes, heart attacks, and death.
Read 9 tweets
Devabhaktuni
Dec 11, 2024
Why Covid risk is flight-duration dependent (box model):

Airbus A321
200 people
1 infector
113 ft x 12 ft x 10 ft
12 air changes per hour (measured by me)

3d plot
Z-axis: infection risk (UC-Colorado estimator)
X-axis: hours of flight
Y-axis: infector's viral exhalation rate Image
Image
Observations (consistent w/ study):

(1) Covid risk (by aerosol) is low for short flights (< 2 hrs)

(2) Risk rises duration-dependently for medium (4-6 hrs and long (> 10 hrs) flights

(3) Risk also depends on how fast virus is exhaled by infector (quanta emission rate)
Caveat: this box model does not take into account nearby infectors which would be much greater risk than if seated further away.

For those old enough to remember "smoking" 🚬 vs smoking🚭sections on flights that helps explains why it is riskier nearby an infected person.
Read 6 tweets

Did Thread Reader help you today?

Support us! We are indie developers!

This site is made by just two indie developers on a laptop doing marketing, support and development! Read more about the story.

Become a Premium Member ($3/month or $30/year) and get exclusive features!

Become Premium

Don't want to be a Premium member but still want to support us?

Make a small donation by buying us coffee ($5) or help with server cost ($10)

Donate via Paypal

Or Donate anonymously using crypto!

Ethereum

0xfe58350B80634f60Fa6Dc149a72b4DFbc17D341E copy

Bitcoin

3ATGMxNzCUFzxpMCHL5sWSt4DVtS8UqXpi copy

Thank you for your support!

Follow Us!

Send Email!

:(