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CO2 is a good proxy for airborne infectious disease risk. Outdoor air is 400 ppm or so, best practice in modern building going into the pandemic was 600 ppm. Ge
by Syzygies 6y ago
CO2 is a good proxy for airborne infectious disease risk. Outdoor air is 400 ppm or so, best practice in modern building going into the pandemic was 600 ppm. Get CO2 down to 450 ppm and airborne infectious disease transmission plummets.
We have varied reactions to parts of the world that still suffer the consequences of human waste in irrigation water. In the far future people will view our current indoor spaces with similar varied reactions.
- bambax 6y agoYes. Or, spend less time inside. That we spend so much time inside is a unique feature of our time, and a very bad one. Regardless of air or sunshine (which are both extremely important to our physical health), not being outside makes us unhappy. People who work outside often sing while working; when was the last time you heard someone sing in an office.
- CleaveIt2Beaver 6y agoThere's also a vast difference in the types of work being done outside vs in an office; when was the last time you heard someone sing while documenting code?
- comice 6y agoI've been wondering about this for a while, do you have a reference? Do you know how humidity affects transmission? Pre-pandemic I used to go indoor bouldering where there tends to be a lot of chalk in the air and I was curious how that affects transmission. Couldn't decide if the dryer air meant less transmission, or the larger particles meant more maybe. Couldn't find anything about it.
- karmelapple 6y agohttps://onlinelibrary.wiley.com/doi/full/10.1111/ina.12639 https://onlinelibrary.wiley.com/doi/full/10.1111/ina.12639
- a_f 6y agoAny evidence for this?
- JshWright 6y agoThe point here isn't that CO2 matters. The CO2 is just a marker for adequate ventilation (and there is plenty of evidence that ventilation is very important in reducing transmission).
- karmelapple 6y agohttps://onlinelibrary.wiley.com/doi/full/10.1111/ina.12639 https://onlinelibrary.wiley.com/doi/full/10.1111/ina.12639
- jgilias 6y agoPeople in not too distant future will likely view with envy the readily available fresh air we currently have. Given that in a century or two the CO2 concentration in outside air may reach the 'stuffy classroom' level[1]. Imagine that, having to live and work in oxygenated habitats on our home planet. https://www.acer-acre.ca/resources/climate-change-in-context/introduction-2/global/scientific-projections/projections-for-carbon-dioxide https://www.acer-acre.ca/resources/climate-change-in-context...
- cbm-vic-20 6y agoThis is a plot element of the movie "Spaceballs".
- Breza 5y agoI was thinking about that the other day when reading about shortages of medical oxygen in India due to the COVID-19 crisis. That movie picked the plot device because it was so ridiculous and now it could be a real problem in some cases.
- karmelapple 6y agoIn case anyone is looking for a citation, here’s a recent peer reviewed study of a Taiwan university and how increasing ventilation greatly reduced tuberculosis infections. https://onlinelibrary.wiley.com/doi/full/10.1111/ina.12639 https://onlinelibrary.wiley.com/doi/full/10.1111/ina.12639
- simonebrunozzi 6y agoAny source for this claim? (I kind of trust you, just wondering if you have a specific source to offer)
- thepete2 6y agoThat's cool and makes total sense as a measure of how "ventilated" a room is, though I'm sure it has its limits.
- jeremyjh 6y agoI assume just installing CO2 scrubbers would have no benefit though, since the CO2 level is just a proxy for how much the air is recirculating.
- Syzygies 6y agoExactly. A proxy.
- Robotbeat 6y agoUnless you use high quality HEPA filtration (and/or UV sterilization?) as well.
- nibsfive 6y agoYes that increases air quality but it would not add oxygen back into the air in place of CO2.
- Robotbeat 6y agoI’ve thought a lot about CO2 scrubbing of indoor air. Oxygen concentrators are cheaper than air scrubbing and much easier to do regeneratively. The simplest and cheapest scrubber is to just use sodalime, but that’s disposable and single-use. A regenerative system that heats up the lime (and vents the CO2 elsewhere) is more complicated and expensive and very energy intensive. Other solutions using amines or other chemicals to remove the oxygen can be more efficient, but many of them don’t work efficiently except at higher CO2 concentrations. We are, of course, talking about miniaturizing a Direct Air CO2 capture system, which usually operates at large scale to get efficiency. Replaceable cartridges that are regenerated at a central location may be a better option. But oxygen concentrators are small and cheap and portable and don’t require much energy to operate.
- gpm 6y agoOxygen depletion doesn't seem to be the issue though, CO2 toxicity does. At 1400ppm CO2, we've turned what, 1000ppm O2 into CO2 (is it 1-1?), or 1% of the atmosphere. Dropping O2 from (Edit: Fixed numbers) 21% to 20%. Or about a 5% reduction in O2 density. Equivalent to approximately 1500 feet of elevation... That's just not that much. (There's also a long list of papers showing issues with CO2 toxicity at low levels of CO2... I keep intending to write a blog post summarizing them)
- quercusa 6y ago> Get CO2 down to 450 ppm And buildings will be much more pleasant. It's possible that people would be smarter, too (as opposed to being shut up in a badly ventilated conference room for an hour or two). There are costs, as heat or/AC will have to run more to keep the temperature in the right range.
- danans 6y ago> There are costs, as heat or/AC will have to run more to keep the temperature in the right range. Heat recovery ventilators can largely solve this problem, while also reducing particulate pollution indoors.
- melling 6y agoInteresting, with climate change CO2 will be increasing to over 450 ppm at some point. Will we have an issue with airborne diseases?
- graeme 6y agoNo the co2 is a proxy for air exchange with the outside. It is the air exchange that prevents disease, not low CO2.
- philwelch 6y agoSubmarines tend to operate at CO2 levels around 3500 ppm, and there doesn’t seem to be strong evidence of any cognitive effects. Infectious disease would be more of a concern, but the submarine itself is a pretty effective quarantine.
- pfdietz 6y agoCounterflow air-to-air heat exchangers mitigate much of that cost.
- quercusa 6y agoI knew about residential ones but it looks like there are commercial ERVs as well: https://www.york.com/commercial-equipment/air-systems/energy-recovery-ventilators https://www.york.com/commercial-equipment/air-systems/energy...