Air ion behavior in ventilated rooms

Air ionizers have seen increasing use as devices for improving indoor air quality, including applications designed to reduce the transmission of infection in healthcare environments. However, little attention has been given to understanding and quantifying the physical behavior of ions in indoor air. This study presents experimental data and a theoretical model to examine the factors that influence the concentration of ions in a ventilated room. The results demonstrate how, with an ionizer in operation, the ion concentration is governed by ion-ion interactions and electrical deposition at the walls, with the ventilation rate having a minimal influence. The results also demonstrate that an ion concentration > 10(10) ions.m(-3) is necessary for these electrical effects to be significant, which has implications for the suitability of an ionizer for a particular location.