One or two research groups have published work on carbon dioxide and cognition. The state of the published literature is confusing.
Here is one paper on the topic. The authors investigate a proprietary cognitive benchmark, and experimentally manipulate carbon dioxide levels (without affecting other measures of air quality). They find implausibly large effects from increased carbon dioxide concentrations.
If the reported effects are real and the suggested interpretation is correct, I think it would be a big deal. To put this in perspective, carbon dioxide concentrations in my room vary between 500 and 1500 ppm depending on whether I open the windows. The experiment reports cognitive effects for moving from 600 and 1000 ppm, and they are relatively large compared to interindividual differences.
I haven't spent much time looking into this (maybe 30 minutes, and another 30 minutes to write this post). I expect that if we spent some time looking into indoor CO2 we could have a much better sense of what was going on, by some combination of better literature review, discussion with experts, looking into the benchmark they used, and just generally thinking about it.
So, here's a proposal:
- If someone looks into this and writes a post that improves our collective understanding of the issue, I will be willing to buy part of an associated certificate of impact, at a price of around $100*N, where N is my own totally made up estimate of how many hours of my own time it would take to produce a similarly useful writeup. I'd buy up to 50% of the certificate at that price.
- Whether or not they want to sell me some of the certificate, on May 1 I'll give a $500 prize to the author of the best publicly-available analysis of the issue. If the best analysis draws heavily on someone else's work, I'll use my discretion: I may split the prize arbitrarily, and may give it to the earlier post even if it is not quite as excellent.
Some clarifications:
- I reserve the right to call off the whole thing at any time during the next week (April 5 - April 11), if there is a simple reason why indoor CO2 is not practically relevant / these results are grossly misleading and someone brings it up in the comments.
- The metric for quality is "how useful it is to Paul." I hope that's a useful proxy for how useful it is in general, but no guarantees. I am generally a pretty skeptical person. I would care a lot about even a modest but well-established effect on performance.
- These don't need to be new analyses, either for the prize or the purchase.
- I reserve the right to resolve all ambiguities arbitrarily, and in the end to do whatever I feel like. But I promise I am generally a nice guy.
(Thanks to Andrew Critch for mentioning these results to me and Jessica Taylor for lending me a CO2 monitor so that I could see variability in indoor CO2 levels. I apologize for deliberately not doing my homework on this post.)
CO2 has been used a marker for acceptable ventilation since the 1920s. Commercial building ventilation systems are often linked to CO2 sensors in the return air, and increase or decrease outdoor ventilation air to meet a set target. Typically 800-1000ppm. This is known as "demand control ventilation", and is pretty common, especially in newer buildings. A tricky thing with this is that the sensors are notorious for drifting out of calibration over time, so many system have minimum damper positions built in to make sure enough fresh air is getting to the space.
Residential and commercial ventilation is regulated under ASHRAE standard 62.1 and 62.2 https://www.ashrae.org/resources--publications/bookstore/standards-62-1--62-2 The standards are set by committee, and are a big battle/tradeoff between (1) energy cost from heating, cooling, and moving all that ventilation air (2) odor, (3) air quality risks (like NOx, particulates, VOCs), and (4) impairment from CO2.
In the most recent update, ASHRAE finally removed the infiltration allowance for residential buildings. Before, residential buildings could be built with just exhaust fans, with the fresh air being made up through infiltration, meaning air coming through cracks around walls, windows, doors, etc. But there was disagreement as to whether this air is really fresh. Insulation tends to "filter" the air and remove particulates, but it can also pick up bad stuff like mold spores, VOCs, etc. The decision was to no longer count infiltration, largely because buildings are getting tighter and shouldn't be leaking that much. Plus infiltration can pull in warm, moist air which can condense in walls if the building is air conditioned, causing mold and water damage. Now, residential must match commercial buildings in supplying fresh, filtered dedicated supply air. That will be BIG change in residential construction practice if/when states adopt it. (1/3 of states don't follow it, 1/3 are keyed to old 2004,2007,2010 standards, 1/3 are recent). For now I recommend cracking open windows, running bath fans occasionally, and ESPECIALLY installing and using a cooking range hood exhaust fan while cooking. Can't emphasize the kitchen range hood enough - thats probably #1 most important thing to do to improve air quality. Well, I'm assuming you're not smoking indoors and not having campfires in your backyard. Those are worse.
There is some question as to whether the ventilation recommendations should be stricter. CO2 is a good proxy for a lot of other air pollutants that are harder to measure. So performance or other benefits from reducing CO2 levels may be coming from getting rid of other air pollutants in the space (VOCs, NOx in particular). However, some recent work out of LBNL has found some slight differences in performance between 600 and 1000ppm.
http://newscenter.lbl.gov/2012/10/17/elevated-indoor-carbon-dioxide-impairs-decision-making-performance/ http://ehp.niehs.nih.gov/1104789/ (study) It would be very tough to stay at 600ppm for most buildings, because that would require a LOT of ventilation air. Doable with natural ventilation, but in places with cold winters? That gets really expensive.
For CO2, OSHA permissible exposure limit for workers is 5000ppm. And NIOSH's short term exposure limit is 30,000ppm, though that would be really bad to be in. There will certainly be cognitive impairment at these levels, but it probably won't cause damage.
If your concern is productivity, work in a ventilated space. Or just open windows / turn on the bath fan / range hood just before you start until after you finish working at home.
If you really want to see some elevated CO2 levels, get in a car with a few other people and go on a road trip without rolling down the windows. And then understand why everyone gets groggy and tired.
ASHRAE also sets ventilation standards for moving transport (airlines, trains, buses), but people are in charge of ventilation in their personal cars or trucks and don't ventilate as much. Or big trucks like semis, where the drivers are already impaired from driving long hours. eek.
If you want more information on air quality and ventilation, check out LBNL's indoor air group: http://indoorair.lbl.gov/ Or NIST's group: http://www.nist.gov/el/building_environment/airquality/
Happy to answer more questions about ventilation / air quality. Interesting field. the elevator "why this is important" (1)http://vizhub.healthdata.org/gbd-compare/ air pollution is a big risk factor a lot of health problems (2)humans spend most of their time indoors (90% + in developed world) (3)a lot of that time is spent sleeping. (4)lots of the world still cooks in their homes with biomass, unventilated. And this pollutes the air in the whole neighborhood. Big problem. Make sure your kitchen, bedroom, and workplace are well ventilated.
Thanks for the information about ventilation.
I linked to the LBNL study in my post. You call the differences "slight," but I'm not yet convinced. Naively, the effects look big enough to justify the expense of maintaining very low co2 levels (e.g. opening windows + running the heat in winter, changing where I work). What I want to better understand is whether those effects are real, what the actual effect size is for tasks I care about, and so on.
I looked at the study again, the reported effects from 2500ppm also just seem totally implausible. On many of the scales they report drops from e.g. 80th percentile to 30th percentile.
10,000ppm causes heavy breathing and confusion, from 50,000ppm upwards you can die in a couple of hours. I don't think going from 80th to 30th on complex cognitive tasks is totally implausible with an increase from 600 to 2500ppm.
I don't understand why you find it so surprising given that (it seems) you had no previous knowledge of the area. Where did your prior come from? I can't be surprised by the fact the Planck length is 1.61x10^-35 and not 2.5x10^-30 given that I had not idea what it was.
ETA: for reference, that's a 500/2400 point drop on the SAT.
Lots of good points here. A couple comments: 1) I don't think it is so critical to ventilate an electric oven/range. But it is important for natural gas and critical for propane or anything else. 2) it is most important to crack open windows and use bathroom fans when the outside temperature is close to the inside temperature because that is when you get the least infiltration from buoyancy (and the increase in heating/air conditioning energy use is small). 3) the increased heating/cooling energy can be mitigated with a heat recovery ventilator