CanAirIO

CanAirIO is a citizen science initiative for air quality tracking, visualization and dissemination by using PM2.5 particulate material sensors paired with your smartphone via bluetooth.

Full Guide:
https://www.hackster.io/MetaKernel/canairio-citizen-network-for-air-quality-monitoring-bbf647

It is a OpenSource initiative:
https://github.com/kike-canaries/android-hpma115s0

It is a OpenHardware initiative:
https://github.com/kike-canaries/esp32-hpma115s0