Thread by @jljcolorado

1/ NEW CAMPAIGN: I'M HELPING @zerocovidthai (with generous support from @AranetloT) to DONATE CO2 METERS to SOUTHEAST ASIA

COVID-19 is mostly transmitted through the air, by breathing in infectious aerosols, in close proximity or in shared room air (thelancet.com/journals/lance…)

2/ For that reason, this is an indoor-dominated pandemic. It is much easier to be infected indoors than outdoors (academic.oup.com/jid/article/22…).

The best infection prevention strategy is do everything that you can outdoors

3/ But we have to go indoors at times.

Measuring the virus in the air is difficult, slow, and expensive.

CO2 indoors marks the presence of exhaled air, and serves as a proxy for the virus (cartoon from @numeroteca)

#covidCO2

4/ This article in @elpaisinenglish provides a good overview of how measuring CO2 works and what we can learn from it:

english.elpais.com/usa/2021-03-29…

5/ There are multiple research papers on this, e.g. ours: pubs.acs.org/doi/10.1021/ac…
onlinelibrary.wiley.com/doi/abs/10.103…
medrxiv.org/content/10.110…

We explain this also in Section 9 of our Scientist’s FAQs: tinyurl.com/faqs-aerosol

6/ So how does it work?

Outdoors there are ~ 400 parts-per-million (ppm) of CO2. Humans exhale ~40000.

So CO2 in indoor air increases, especially with poor ventilation. Often it reaches 2000, 3000, 5000, and we have seen up to 7000 ppm.

7/ If CO2 indoors is 800 ppm, 1% of the air is “second-hand” and has been in someone’s lungs before. If it is 2400, that’s 5%. That is quite risky, if an infected person is present.

8/ We recommend keeping CO2 indoors below 700 ppm at all times during pandemic, & below 1000 if the location has good filtration (filters remove virus but not CO2)

Measuring CO2 --> are we ventilating enough? (or too much?. Especially useful for natural ventilation (windows)

9/ CO2 serves as indicator of RELATIVE risk anywhere (e.g. a choir rehearsal with half the CO2 enhancement is twice as safe as original; same for library)

- ABSOLUTE risk at the same CO2 is much higher at choir rehearsal than library

(More details: pubs.acs.org/doi/10.1021/ac…)

10/ Which factors increase risk? (for same CO2)

- Strong vocalization (more virus out)
- No masking (more virus out & in)
- Breathed volume (e.g. exercise, more virus inhaled)
- Event duration (more inhaled)
- Infection rate in population (higher chance of infected present)

11/ You can estimate the amount of CO2 present in a given activity with our COVID Aerosol Transmission Estimator:

tinyurl.com/covid-estimator

If you do the measurements for an activity, adjust ventilation rate till you match observed CO2 *average*

12/ Many national and international bodies recognize the usefulness of CO2 and have issued recommendations for indoor levels. For example the US CDC recommends portable CO2 meters to monitor natural ventilation:
cdc.gov/coronavirus/20…

13/ The Belgian government recently required CO2 meters in high-risk locations (bars, restaurants, gyms):

14/ The Science Task Force in Switzerland has published similar recommendations, as have multiple other countries:

15/ The Spanish Minister of Science tweeted that "the most important thing to do now is to ventilate and measure CO2":

16/ Measuring CO2 is not just useful during pandemic. After, it should be kept below 1000 ppm at all times. Because there is significant cognitive decline above that level, and there are other health issues due to indoor contaminants.

17/ This was already a law in some countries before the pandemic (mdpi.com/2073-4433/9/5/…)

ncbi.nlm.nih.gov/pmc/articles/P…

18/ Fortunately, there are now affordable, fast, and reliable CO2 monitors.

They are based on non-dispersive infrared (NDIR).

AVOID other CO2 meters (even though they can be cheaper), they don’t work well or at all.

19/ @EJimenez_UCLM has led the testing of many NDIR meters and has some recommendations of those that work well, as well as the features we recommend.

bit.ly/monitorsCO2

(Testing is done in Spain, but many of those are available globally)

20/ And it should always be displayed publicly in all spaces where we share the air

21/ This is part of a paradigm shift in the importance of indoor ventilation for reducing respiratory infections, which has been ignored everywhere for a century:

science.sciencemag.org/content/372/65…

22/ For example, shared cars are especially dangerous (if we don't pay attention), because they have a small volume, and if windows are not open and outdoor ventilation is off, exhaled breath accumulates very quickly.

23/ And this is an explanation of the dynamics of shared cars from @elpaisinenglish, but it is applicable to other indoor spaces.

24/ We have previously donated 120 CO2 meters to Spain and Latin America (with donations from many of you through GoFundMe, @citlanx, @AranetIoT @EspanaAranet, and myself).

25/ Thanks to the initiative of @zerocovidthai, and with gracious support and donation from @AranetIoT / @SAFTehnika, we are starting a new campaign for Southeast Asia.

26/ We can accept requests from Thailand, Philippines, Indonesia, Malaysia, Vietnam, Singapore.

Not sure whether we can send donations to Cambodia, Myanmar, Laos, East Timor, Brunei. (You can apply from those countries, but we’ll have to see whether shipping there is feasible)

27/ We will distribute #Aranet4 meters, which work well, as verified in multiple tests by scientists, e.g. by @EJimenez_UCLM (tweet above), or this testing by @HuffmanLab_DU:

28/ The Aranet4 meters are small and discrete, and they save the data for several days. So you can just have them in a pocket or purse, and look at the data at the end of the day or after several days. This is an example of my visit to a dental office:

29/ We would like to donate the CO2 meters to scientists, health care workers, activist, journalists & others who can measure in multiple places and make the information public, e.g. in Twitter or Instagram using the #covidCO2 tag.

30/ We normally have 5-10 times more requests than available meters to donate, so a commitment to share the information (and the meter) is important.

31/ 35 of the meters are donated by @AranetIoT, but we are raising funds to extend the campaign to another 35 meters (purchased w/ large discount). If you can, please donate at: gofund.me/2e169c20

All the funds will be used to buy CO2 meters (minus a ~1% fee from GoFundMe)

32/ If you want to request a meter, please enter your information in English in this form. We will select & announce the winners in Twitter/Instagram. There are ++ more requests than meters, so pls explain well how you would use and share the meter.

forms.gle/ukBuNcM5Xbjmoo…