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Prof. Jose-Luis Jimenez Profile picture
@jljcolorado
Nov 23, 2021 • 18 tweets • 14 min read • Read on X
Scrolly
1/ HOW TO AVOID TRANSMISSION and have #CleanAirHolidays?

Most important: understand and explain clearly that we get infected by breathing infected air (aerosols) exhaled by SOME (not all) the infected

Mainly in close proximity, and in shared room air

journalofhospitalinfection.com/article/S0195-… Image
2/ Recognize that this is an INDOOR PANDEMIC

20 times more likely to get infected indoors than outdoors (can only be explained by airborne transmission)

DO EVERYTHING YOU CAN OUTDOORS (family and work meetings, schools etc.)

pubmed.ncbi.nlm.nih.gov/33249484/
nytimes.com/2020/07/17/nyr… Image
3/ If you have to go indoors, there is NO SILVER BULLET. You need to do multiple things to reduce risk.

I.e. the "SWISS CHEESE" model of @MackayIM

#CleanAirHolidays Image
4/ A mnemonic to remember what to do: "A CIVIC DUTY"

time.com/5883081/covid-…

#CleanAirHolidays Image
5/ Try to MINIMIZE time spent INDOORS, and with as few people as feasible. Understand that distance helps, but is not enough

#CleanAirHolidays

numeroteca.org/cat/en-el-aire/ Image
6/ Understand that PLEXIGLASS BARRIERS help in a cashier / teller situation. But they actually INCREASE TRANSMISSION when lateral, as they make ventilation more difficult.

dx.doi.org/10.1126/scienc… Image
7/ Understand that DISINFECTION OF SURFACES is an UTTER & COMPLETE WASTE OF TIME AND MONEY

(except perhaps in hospital COVID ward, per the @CDCgov)

nature.com/articles/d4158…
cdc.gov/mmwr/volumes/6…

#CleanAirHolidays Image
8/ Understand that LOUD VOCALIZATION (talking, yelling, singing) is STRONGLY associated with transmission.

Talking less loudly (or not talking when possible, e.g. public transportation) reduces transmission a lot.

arxiv.org/abs/2009.04060

#CleanAirHolidays Image
9/ MASKS are the most effective layer of protection indoors.

bmj.com/content/375/bm…

MASKS ARE NOT SIEVES, they can filter aerosols much smaller than the gaps in the mask through microscopic mechanisms.

medium.com/@asit.mishra76…


#CleanAirHolidays Image
10/ Any mask is better than no mask. But to work best, masks need to:

1) Be a good filter (aerosols stick to it when air goes through its cloth)
2) Let us breathe (low resistance)
3) NOT LEAVE GAPS between face & mask - BIGGEST PROBLEM IN THE REAL WORLD
Image
11/ Since #COVIDisAirborne and AIRBORNE IS THE DOMINANT mode of transmission (see our paper in @TheLancet, thelancet.com/article/S0140-…), we should recommend higher quality masks, especially for riskier situations when sharing indoor air

FFP2/3, N95, or elastomeric

#CleanAirHolidays Image
12/ How to GET RID OF VIRUS IN INDOOR AIR?

1) Get rid of air & floating virus: ventilation - BEST
2) Keep air, remove virus: filtration - GOOD
3) Keep air + floating virus, "kill" virus: disinfection - DANGEROUS, AVOID (except UV disinfection, does work)

#CleanAirHolidays Image
13/ How to know that VENTILATION IS GOOD ENOUGH?

Measure CO2 with an infrared meter (NDIR, ~$100). Keep it below 700-800 ppm (parts per million)

See section 9 of Bit.ly/FAQ-A

#CleanAirHolidays Image
14/ Install PUBLICLY-VIEWABLE CO2 meters everywhere where we share indoor air

(Can be done for low cost $200 or so per location -- much lower than pandemic economic losses)

See section 9 of Bit.ly/FAQ-A

#CleanAirHolidays Image
15/ If ventilation is not sufficient or practical, then go with FILTRATION.

- Commercial HEPA filters: work well, but they are expensive, huge variation in cost, quality, and noise (many companies selling substandard ones)

#CleanAirHolidays

Image
16/ But filters DO NOT NEED TO BE HEPA!! Cheaper filters built with a regular (Comfort) fan and HVAC filters work just as well and are much cheaper. E.g. #corsirosenthalbox

#CleanAirHolidays

en.wikipedia.org/wiki/Corsi-Ros… Image
17/ For more information on the science, the historical errors that have made it so difficult for @WHO and @CDCgov and other govs. to accept that #COVIDisAirborne etc., see this thread and the linked articles and threads:



#CleanAirHolidays
18/ Este mismo hilo en español / castellano:

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More from @jljcolorado

Prof. Jose-Luis Jimenez Profile picture
May 26
1/ Survey of CO2 indoors during trip

CO2 (above ~400 ppm outdoors) indicates the amount of exhaled air (& virus) trapped in a space

Also per recent scientific results by @ukhadds, CO2 helps SARS-CoV stay infectious in air much longer

@united flight boarding, pretty terrible! Image
2/ This is the trip so far:

-Low outdoors
-Pretty high ~2000 in @RideRTD bus to airport
- ok ~800 at @DENAirport, except restroom ~1500. Not sure why restrooms at this airport are so often poorly ventilated
- Then boarding on @united, ventilation OFF, so huge increase till ON Image
3/ For details of the recent results on how and why CO2 makes SARS-CoV-2 stay infectious much longer in the air, see this recent thread by @ukhadds

Read 9 tweets
Prof. Jose-Luis Jimenez Profile picture
May 8
1/ "After four years of fighting about it, @WHO has finally proclaimed that viruses, including the SARS-CoV-2 virus that causes COVID, can be spread through the air"



By @maggiemfoxscientificamerican.com/article/a-figh…
2/ "It took four years to get here because some leaders in public health, medicine and science clung too tightly to precision and semantics"

"One particular moment of shame came on March 28, 2020, when WHO tweeted: “FACT: #COVID19 is NOT airborne.”

3/ "Words matter. When people heard that COVID might spread on surfaces, they wasted time wiping down groceries. People who misunderstood airborne spread needlessly wore masks on outdoor walks and veered off sidewalks to avoid their neighbors."
Read 7 tweets
Prof. Jose-Luis Jimenez Profile picture
Apr 18
1/ @WHO has published a report on updated terminology for disease transmission

I've seen some debate about it. My take:

- Terminology itself is ok. Big progress
- But no recommendations of how to protect!

Report:

Press release: who.int/publications/m…
who.int/news/item/18-0…
2/ The report was likely the result of intense pressure on @WHO during the pandemic:

- They denied that #COVIDIsAirborne on March 2020
- They finally accepted it 2 years later

nature.com/articles/d4158…
@WHO 3/ To their credit, @WHO did invite some of their critics to be part of the committee.

What was the terminology before. In medical circles:

- droplet transmission: if it happened in close proximity, or if particles were > 5 microns

- airborne transmission: if it happened far
Read 34 tweets
Prof. Jose-Luis Jimenez Profile picture
Mar 28
1/ New paper in @ScienceMagazine: "Mandating Indoor Air Quality for Public Buildings"

Explaining current status of indoor air quality standards (in short: bad or non-existent), the huge health benefits that would arise from them & proposing a path forward
science.org/doi/10.1126/sc…
Image
2/ "People living in urban & industrialized societies, which are expanding globally, spend more than 90% of time indoors, breathing indoor air (IA)."

"Most countries do NOT have legislated indoor air quality (IAQ) performance standards for public spaces"

science.org/doi/10.1126/sc…
3/ "Few building codes address operation, maintenance, and retrofitting, and most do NOT focus on airborne disease transmission."

"We propose that Indoor Air Quality (IAQ) standards be mandatory for public spaces"

science.org/doi/10.1126/sc…
Read 14 tweets
Prof. Jose-Luis Jimenez Profile picture
Oct 4, 2023
1/ Checking the ventilation by measuring CO2 as I travel to the #AAAR2023 conference

@RideRTD bus to Denver airport. Bus route had started 3 min before I got in, already 1500 ppm

Typical of these @RideRTD buses, poor ventilation Image
2/ Not getting any better as time passes in the @rideRTD bus to the airport...

7% of the air is being re-breathed, it has already been in someone else lungs when each of us breathe it. Image
@RideRTD 3/ Given the often poor-to-mediocre ventilation in US transportation systems, I wear N95 masks (not KN95, less good)

In this case @3M VFlex, which I tested at 99.99% filtration for myself

It also stays sealed when I talk, doesn't distort my speech (& add to my Spanish accent) Image
Read 14 tweets
Prof. Jose-Luis Jimenez Profile picture
Oct 2, 2023
1/ Video de mi presentación sobre "Transmisión de enfermedades por el aire: cómo funciona, por qué se malentendió, y cómo reducirla"

como parte de la presentación del libro de ventilación de @aireamos

2/ Las diapositivas se pueden bajar de este enlace.

(Son de una charla más larga así que tienen más detalles, pero están todas las de la presentación de @Aireamos)

drive.google.com/file/d/1Bs0RRG…
@aireamos 3/ Miguel Ángel Campano @MA_Campano y @Aireamos han sido los motores del libro de ventilación:

Read 4 tweets

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