I live in an old building that has a lot of cracks and gaps for air to circulate, so it rarely comes close to 2000ppm. When I leave the house for a longer perio

I live in an old building that has a lot of cracks and gaps for air to circulate, so it rarely comes close to 2000ppm. When I leave the house for a longer period of time (hasn't happened in a while), you can see the value slowly approaching the outside baseline. And in the night, while I sleep with the windows closed, I produce much less of it, so I don't get super high values there either. But the rise is quite interesting! It differs a lot based on some factors, such as am I asleep, awake, or working out / are any doors open, i.e. how big is the volume of air I'm in?