the effects generally seem to be small
I don't know about that. Anecdotally, I know some people who say that how well they think/work/feel is noticeably -- to them -- affected by weather, mostly a combination of pressure and humidity. Also anecdotally, the older you get, the more sensitive to weather your body becomes.
Myself, I feel more energetic in high-pressure low-humidity weather than in low-pressure high-humidity, but I haven't tried to quantify it or be rigorous about it.
Anecdotally, I know some people who say that how well they think/work/feel is noticeably -- to them -- affected by weather, mostly a combination of pressure and humidity. Also anecdotally, the older you get, the more sensitive to weather your body becomes.
People think a lot of mistaken things about their personal psychology. But the weather correlations are still small: 'Does Life Seem Better on a Sunny Day? Examining the Association Between Daily Weather Conditions and Life Satisfaction Judgments', Lucas & Lawless 2013; 'Subjective wellbeing: why w...
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 on cognitive effects for moving from 600 and 1000 ppm, and finds significant effects 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:
Some clarifications:
(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.)