Opening the windows is a solid choice. I keep a CO2 monitor in my office. So long as I keep the door open, levels usually stay below 800ppm, but if I close the door they can climb rapidly within an hour or two. I have a CO2 meter tied to an alarm to remind me to open the window if they get too high. I probably should have it set to 800, but I found that to trigger too often so I upped it to 1200.

I use a RAD-0301, which works fine as a monitor and an alarm by itself, but which I connect to a Raspberry Pi for dashboard purposes using the code shared here: https://news.ycombinator.com/item?id=22764488

Anything that moves the air is fine. And yes, opening windows would be a sensible thing to do in that context.

That said, I'm not sure I buy the thesis as a whole. As far as I am aware, last time this came up, the Navy has done pretty detailed tests on CO2 concentration as a result of submarine warfare and found no significant impairments up to 1200ppm.

I wish there was a freeway down the street. Then the cars would be here and gone instead of idling in our local streets for fifteen minutes waiting to merge. Here's a real-world study of before and after they tore down two exits of the Central Fwy and built the horrible Octavia Blvd that necessitated a bunch of sidewalk closures and keeps killing cyclists: https://archive.sfcta.org/sites/default/files/content/Planni...

If you have central heat/ac your thermostat might have a switch to convert it from 'auto' to 'on'. You can combine that with turning off the heat/cooling such that it's just a house/apartment-wide fan. I do that at night before going to bed to deal with poor airflow in my bedroom and according to my CO2 sensor, it works. It works correctly even if I leave it set to cool or heat, the thermostat still controls whether it's actually heating or circulating air. Likely what you have is the same.