The airborne contaminants cannot be eliminated by mechanical ventilation or filtering,but they can invade again into other air-conditioning zones via returning or recirculated air.This paper mainly focuses on the utilization of ionizers in ductwork for removing particulates from indoors.The selected room was separated into two rooms but served by one ductwork.The ionizers were installed at different locations inside the ductwork.A pollutant source was released in one of the two rooms.The governing transportation equations for negative ions and pollutant(Escherichia coli)were modeled and numerically solved by implementing them into FLUENT as user scalars.The simulation results show the contaminant was removed and the application of ionizer can effectively block the pollutant entering into other clean rooms.By comparing 4 ionizer installation scenarios,it is concluded that both the return and supply inlet should be mounted an ionizer to get the highest removal efficiency.