[57north-discuss] CO2 sensor

hi folks, I have a suspicion my home office does has issues with CO2 accumulation when windows/doors are closed, which makes me sleepy. It is that, or my work is not challenging enough ;-) To rule out the latter, I would like to test the indoor air quality for a couple of days. Has anyone got perhaps an unused CO2 sensor lingering about, or Chinese rip-off of the SCD-40 sensor, that I could use for a couple of days? Cheers, Wouter (Aberdeen)