A special thing we do at work because I asked for it is that we have CO2 monitors in the meeting rooms. These measure the levels of CO2 levels in the air. In modern times the usual level outdoors is around 440 ppm. You will have some discomfort at 700, 800 ppm and solid amounts of drowsiness at 1000 ppm. The OSHA limit is 5000 ppm for a day, but you will have significant reduction in cognitive capacity at 1000 ppm. Usually in a crowded meeting with the windows closed we can get to 1300, 1400 ppm, and when we crack the windows we get down to about 700 ppm.
You definitely notice the levels. We had to close the window the other day during a planning meeting because fleet week was starting in SF and there were loud planes outside. One of the other devs was attentive at 700 ppm but practically conked out at 1400 ppm. My attention was also wavering.
This is a surprisingly high ROI thing we did. The monitors are pretty expensive for an individual (like $100, $150 on Amazon) but not at all for a corporation, because there will be multiple people getting paid to be in a meeting, all of them possibly impaired, possibly making important decisions, possibly talking to clients, possibly handling emotional situations.
One of the law firms we work with actually ended up getting it for their own meeting rooms, when they asked about it (we sell a GDPR and CCPA thing that handles third-party integrations and other stuff for you, so we talk to lawyers all the time).
If you don’t read the above linked paper, it’s worth it to note that their measure of personal initiative was one of the ones highest impacted by high CO2 levels.