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! 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

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.”

https://twitter.com/who/status/1243972193169616898

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…

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…
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…

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 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.

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…

1/ Measuring CO2 indoors in a 10 day trip from US to Europe & back

Bus @RideRTD to Denver airport, poorly ventilated as usual.

We have not left town yet! In previous trips it kept increasing, we'll see this time. 2/ For background on what CO2 indoors indicates and more details, see

TLDR:
- We exhale 40000 ppm CO2
- Outdoors: 420
- Each 400 extra ppm indoors = 1% extra rebreathed air
- CO2 makes us dumber, indicator of virus & pollutants. Does not capture filteringdocs.google.com/document/d/e/2…

1/ Webinar from @PsrColorado on mixing hydrogen (H2) with fossil (aka "natural") gas

- NOT a good idea
- Subsidized by Inflation Reduction Act in US

- Creates problems, but less at the point of combustion, more elsewhere 2/ "Brown hydrogen" is made from coal

HUGE CO2 emissions, unacceptable

1/ The Model State Indoor Air Quality Act #MSIAQA has been released today. Developed by the Johns Hopkins Center for Health Security @JHSPH_CHS, with advice from an extensive group of experts, led by @polsiewski et al.

centerforhealthsecurity.org/our-work/resea… 2/ The background is that the US Federal Govt. has not, and likely will not, regulate air quality.

This text, from the intro of the #MSIAQA, explains why:

"Enhanced Ventilation and Cleaner Air in Buildings"

A Webcast from the US National Academies of Sciences, Engineering, and Medicine @theNASEM

STARTS in 10 min, can watch online

W/ @WBahnfleth, V. Loftness, B. Gilligan, K. Keene

nationalacademies.org/event/40066_07… Workers were only satisfied with their air quality when CO2 < 600 ppm. Sobering.

1/ My upcoming Webinar on HEALTH BENEFITS vs DISBENEFITS of AIR CLEANERS

On Wed. 2-Aug. 11 am Colorado time, 1 pm US East Coast, 9 pm Central Europe

Link to register:

TLDW:

- some air cleaners: benefit >> harm
- For others harm > benefit (or at times)register.gotowebinar.com/register/71654… 2/ The webinar will be pretty technical, at the level of a typical scientific seminar. I'll do my best to explain the material, but it may be hard to follow for people without sci/tech background.

I'll eventually do a Twitter thread or Substack post on it.

1/ IMPORTANT: (esp. scientists & health care workers, but open to anyone) please SIGN (by 17-Jul) this letter to the @CDCgov to support open scientific discussion of airborne precautions in health care

At present @CDCgov is planning to WEAKEN them! (Can't make this stuff up!)

https://twitter.com/brosseau_lisa/status/1678777060196745217

2/ Mirroring the early pandemic, and obviously not having learned much from it, @CDCgov has a committee (HICPAC) comprised ONLY of Infection Control Folks (Yes, those that told us to wash our hands and clean surfaces early on, and took forever to accept airborne) & HC industry

1/ How Safe Is Your Office Air? There’s One Way to Find Out.

"Some companies are turning to technology to illuminate potential hazards in indoor air."



By @EmilyAnthes in the @NYTimesnytimes.com/2023/06/29/hea… 2/ "In the United States, there is little regulation of indoor air quality, and once a building is up and running, occupants typically have little insight into whether the air they are breathing is safe.

Indoor air-quality sensors make the invisible visible."

"Using a single gas-stove burner can raise indoor concentrations of benzene, which is linked to cancer risk, to above what’s found in secondhand tobacco smoke and even to levels that have prompted local investigations when detected outdoors"

nytimes.com/2023/06/17/cli… "Dr. Janice L. Kirsch, an oncologist and former investigator on a large-scale study of childhood leukemia who was not involved in the Stanford research, said the levels of benzene the researchers found coming off gas stoves in peoples’ homes were alarming."

1/ Travelling from Colorado to New York City for #ICFUST conference with low-cost air quality sensors.

New: @2b_technologies POM portable ozone monitor.

Semi-outdoors waiting for the bus:

-CO2: 588 (some exhaust)
-PM: 0 (rained yesterday *)
-VOC: 65 (low)
-O3: 15 ppb (**) 2/ Some expl:

@RideRTD Boulder bus station, like a tunnel open on both sides. Modern diesel buses running

- some CO2 from diesels
- Ultrafine PM, low-cost sensors can't see (too small for their lasers)
- Diesels emits very low VOC
- Emit NO, which destroys O3

All checks

1/ We just installed an (outdoor) volatile organic compound (VOC) real time instrument at the Denver site of @NSF @ASCENT_USA measurement network

We are very grateful to @tofwerk, who's lending it to us for a month & to @CDPHE who is our host

Here w/ the ASCENT instruments 2/ Here a close-up of the instrument, a Vocus Elf PTRMS (proton-transfer reaction mass spectrometer)

The sensitivity & resolution are lower than for the top-of-the-line research instruments, but this is still as sensitive as the quad PTRMS who were state of the art a decade ago

1/ Surveying indoor ventilation in the US as I travel to a conference

I'll use Aranet4 CO2 meter (see next tweet for details)

At the @RideRTD Bus to the airport ventilation is very poor, worse than what I measured previously (but similar to meas. by others such as @DougChem ) 2/ How to interpret indoor CO2?

- Measured in parts per million (ppm) (how many molecules of air are CO2, out of each million)
- outdoor is 420 ppm
- exhaled air is 40000 ppm
- indoor is higher than outdoor due to human accumulated exhalation
- good ventilation? 800 or better

1/ INDOOR AIR QUALITY while on travel

I'll post usual CO2 levels, but we'll measure several more pollutants w/ @airthings & see what we learn

@RideRTD bus to Denver airport: CO2 borderline (ventilation indicator), PM low, radon at outdoor levels (as expected) 2/ Two more observations:

- @airthings CO2 (NDIR) tends to be lower than Aranet4. Not sure why, but we and others have tested Aranet extensively, so I trust it more.

- @airthings complains about low humidity, but we are in Colorado and they are from Norway...

1/ Electric Vehicles Keep Defying Almost Everyone’s Predictions

"There are now almost 30 million electric vehicles on the road in total, up from just 10 million at the end of 2020. E.V. market share has also tripled since 2020."

nytimes.com/2023/01/11/opi… by @dwallacewells 2/ "In 2020, the International Energy Agency @IEA [famous for its poor predictions] projected that the global share of electric vehicle sales would not top 10% before 2030. It appears we’ve already crossed that bar 8 years early"

[We need this to go fast to #EndFossilFuels]

US federal agency considering a ban on gas stoves

"US Consumer Product Safety commissioner said gas stove usage is a “hidden hazard.” Any option is on the table. Products that can’t be made safe can be banned"

Would be great win for #IAQ #EndFossilFuels

cnn.com/2023/01/09/bus… We have to get rid of gas turbines and home furnaces as fast as possible too (for climate reasons especially). But those ony pollute outdoor air, so we breathe 1000 times less of those exhausts vs. cooking stoves. Stoves are terrible for indoor pollution.

https://twitter.com/ltsailsFL/status/1612856864563236887

1/ Germicidal UV: a tradeoff between disinfection and indoor smog

A Substack (blog) post with a first estimate of the magnitude of the tradeoff.

TLDR: still uncertain, but GUV smog is likely to be a significant concern, needs to be carefully evaluated.

jljcolorado.substack.com/p/germicidal-u… 2/ This post builds upon the results of our just-published paper, in which for the first time we evaluate the indoor air quality impacts of GUV disinfection.

pubs.acs.org/doi/10.1021/ac…