I build a combined real CO2/ppm monitor 3 years ago and I leaned quite a bit about indoor CO2 accumulates in practice and how to actually prevent it building up

I build a combined real CO2/ppm monitor 3 years ago and I leaned quite a bit about indoor CO2 accumulates in practice and how to actually prevent it building up at all. This is from a single sensor I moved around over months so I might have drawn the wrong conclusions but CO2 seems to "pool" at lover heights and "fall" over surfaces such as tables from a "source" such as a human breathing. So don't put it on your desk surface but somewhere else in the room. Also it seems to take a long time for a well ventilated space to build up to high CO2 levels - days for my apartment. I could entirely prevent any buildup at measuring heights of it by not quite closing a window furthest from my apartment door. My theory is that movent in the hallways of my apartment building slowly pushed air out that window thus replacing the air in my apartment fully over days. By not quite closed I mean closed but the lever that presses the window into its the seals only slightly engaged. A Year after I started my Measurements there was some maintenance done on the windows to make them more airtight. Since then I do not need to keep the window half closed anymore because I can't get the CO2 meter to show anything but baseline except when sitting right in front of me on my desk.