[shashurup]

> The remainder of my day was spent alone in my home office with the door open. My CO2 levels at home varied between 750 and 800 ppm.

This made me think about my device accuracy. With open door it is usually well below 400ppm (which seems to be an artificial lower limit of the device).

Finally, I think my device is ok - with door and window closed it gets to 800ppm in about 2-3 hours which seems quite reasonable.