Air Ion Counter
The Air Ion Counter is a handheld meter designed to measure ion density-- the number of ions per cubic centimeter (ions/cc) in air. It measures this number separately for positive and negative ions (+ and - ions are usually present simultaneously). This instrument is a true ion density meter, based on a Gerdien Tube (Gerdien Condenser) design, and it contains a fan which pulls air through the meter at a calibrated rate. The standard model measures up to 2 million ions/cc (for comparison, outdoor air typically has 100 to 1000 ions/cc, both + and -). The 2 million range is sufficient for almost all situations except for measuring very close to electric ionizers or strong radioactive sources.