Bought one to use as a real-time NDIR CO2 monitor and was impressed with the response-time/refresh-rate. Seems to measure just about as accurately as our Netatmo weather station indoor unit.
Portability is great, took it on a car journey with 4 people in the car; CO2 levels went from 400+ at the start of the trip, to over 3000ppm after 12 minutes with the air-con on re-circulate!
Do they have a model that detects endogenous gas ?