Paris famous pollutant is NO2 gas so this Raspberry Pi monitor was born to keep track of concentration change. The idea was to make portable sensor box so it is powered from 8Ah battery backpack used to recharge other devices like iPhone. But most time it stays connected to power source like wall adapter. Since RasPI doesn’t have analog input there is a small custom ADC board attached to I/O which takes readings from AlphaSense B4-series analog sensor.
Raspberry PI simply reads sensor data and sends it via GPRS dongle. Using only NO2 sensor would be too much of overkill, so there are intentions to add more sensors including O3 and SO2. And there is still plenty of room for upgrades.