Utilising a MH-Z19B CO2 sersor, CSS811 TVOC sensor and a ESP32 micro controller this monitor displays a real time graphs.
It also has a companion Bluetooth app that connects to the Air Monitor to receive live updates of the values as well as a 24 hour graph of the CO2 concentration.
I designed and printed the case, as well as programming the micro-controller firmware plus the Android app.
Build your own here: https://www.thingiverse.com/thing:4126483
Souce code is here: https://github.com/wilyarti/dustMonitor