Abstract: An apparatus and method for monitoring the output of an ionizing blower. A measuring channel captures a portion of the air ion stream, and measures balance plus air ion current. Since the measurement channel is isolated from extraneous electrostatic fields, measurements contain less analytical noise. Air flow through the measurement chamber is created by the inherent pressure difference between the high pressure and low pressure sides of an air mover. Two electrodes inside the measurement chamber are combined with a power supply, a low current amplifier, and a controller. The controller also makes adjustments to the ionizing blower.