An air ionization monitoring device 200 and method is disclosed herein. In a described embodiment, the air ionization monitoring device 200 comprises an ion source 202 adapted to emit ions 204 and a capacitor 208 including a first conductor 210 arranged to be exposed to the ions 204 emitted by the ion source 202, and a second conductor 212 arranged to be shielded from the ions 204 emitted by the ion source 202. The monitoring device 200 further includes a commutation circuit 234 operable between a first configuration for charging the capacitor 208 to a first predefined voltage, and a second configuration for using the ions 204 emitted by the ion source 202 to discharge the capacitor 208 for a predefined time resulting in the capacitor 208 having a second voltage. The device 200 is configured to use the first and second voltages to determine an ionic current of the emitted ions.