I am really interested in the app, it is one of the reasons why I bought this cell, I would like to integrate a sound / text alarm when the CO2 ppm "gas" values exceed a certain threshold.
Also can I know the sensor model used?
Is it possible to have more details and maybe the source code of the app?
I would be really happy to collaborate and try to improve this feature.

Please let me know

If anyone else is interested in contributing here are some readings that I have found
Doc: 

• https://codelabs.developers.google.com/codelabs/advanced-android-training-sensor-data/index.html?index=..%2F..advanced-android-training#3
• https://developer.android.com/guide/topics/sensors/sensors_overview
• https://developer.android.com/guide/topics/sensors/sensors_environment#java