I want to thank, representatively for all non-named,
@dagl.bsky.social
@protectthekids.bsky.social
@igoe.at
@winslowsp.bsky.social
@associationarra.bsky.social
@ruthbrooker.bsky.social (@CleanAir4KidsUK)
@cleanairie.bsky.social
@nousaerons.bsky.social
for all their amazing work.

Which CO2-sensor do you use (guess that's the component in the left of the image?)

Ja genau, aber (deutlich) langsamer.

Und noch viel trivialer einfach das mit China ein Land das 15 so groß ist wie Deutschland inzwischen eine eigene Industrie aufgebaut hat und sowohl in China als auch dem Weltmarkt als Konkurrent auftritt. Bei Verbrennern hätte es vllt. paar Jahre länger gedauert, bis die Auswirkungen so groß sind.

And I guess for academic research there is always a strong bias towards innovative methods to get published (and get funding) rather than doing the same experiment in 10000s of variants (not blaming the scientists for that ... it's a systemic issue).

Having more experimental data for many viruses and variants, more fine grained (maybe in 100ppm steps) would be useful to understand better how ventilation changes impact different Viruses - but I guess instead of funding stuff like this, Billionaires prefer to invest in Powerpoint-Fusion-Reactors.

Even if this is just one Example and the influence a change in the decay rate has varies most likely widely for different viruses and different CO2-concentration changes, in this case at least the change in the decay rate nearly has the same effect size as the ventilation itself.

For this example you can see that the change in ventilation would reduce the particle count by a factor of 2,5 but because the decay rate also changes it is reduced by a factor of 5. Now for Omicron this is less pronounced but as there is no decay time series for Omicron I used Delta values.

Investing into powerplants which takes 10+ years to complete does not make sense if you assume that there are massive AI-innovations withing the next 3-5 years which would make your investment completely obsolete even before the powerplant is finished, let alone over the lifetime of the powerplant.

While Experiments where the CO2 came from the participants do reliably find results. If it is CO2 directly then it's one more totally neglected neglacted impact of climate change. (Even the uncertainty should be enough to consider the risks...). We'd not only boiling the planet, but also our brains.

Yep there already effects shown at 800ppm and below ... now the fun question is, does CO2 directly cause it or is it something which correlates with exhaled air), which too my knowledge is still an area of dispute, some experiments adding additional CO2 to rooms didn't find effects.

But from a practical viewpoint. A Building owner cant do much about the outdoor air concentration, but can impact value above baseline with Ventilation. (PS: post about exhaled air above assumes no other relevant CO2 source aside from people is in the room)

So for this absolute value is relevant. Higher CO2 Levels also seem to have negative Cognitive effects ( although there is still uncertainty if it is CO2 directly causing it or again just correlation with exhaled air. So neither total nor relative values are Perfect.

Value above outdoor Correlates with amount of concentration of exhaled air (each ~400ppm above Baseline = 1% exhaled air), so from that Perspective it makes Sense to use this as baseline. However for some viruses higher absolute CO concentration also increases time Virus particles stay infectious.

To think that a higher R0 means its necessarily easier to combat is obviously also not sound - it depends on how strongly R0 of a virus can be changed by changes to the environment and I think that's currently especially for airborne diseases a field where large knowledge gaps exist.

Which shows that simplistic arguments like "Virus A has a higher R0 than Virus B so its harder to combat" are unsound, wrongly treating R0 as somthing intrinsic to the Virus rather than the virus+environment (which is the proper definition) or treat the environment wrongly as unchangeable.

Lets assume everything else about these Viruses is identical, then in a low-ventilation environment, Virus A would be more infectious; with high-ventilation Virus B would be more infectious. So depending on the environment either Virus A or B could have a higher Basic Reproduction Number (R0).

In the above example there are 2 theoretical viruses which only differ in emission rate of the host and the half-life. At low ventilation rates Virus A with lower emission rate but longer half-life ends up at a higher equlibrium level of particles, at high ventilation its Virus B which is higher.

Which is totally intuitive when thinking about the extreme cases: if you had instant decay, even without any ventilation the virus particle count wouldnt build up, if you had no decay at all then without ventilation the virus particle count would grow "forever".