Numerical analysis for evaluating the “Exposure Reduction Effectiveness” of room air cleaners

An “Exposure Reduction Effectiveness” index is proposed to quantify the performance of room air cleaners based on their capability of reducing occupants' exposure to pollutants of interest. The index has advantages over existing index such as CADR. It is applicable to both room average and local breathing zones, and can be used to compare air cleaning with the other two IAQ strategies: ventilation and source reduction. A computational fluid dynamics model is developed and used to assess the effectiveness of a room air cleaner for VOCs and particles of different sizes. The simulation results show: (1) species transport model and drift-flux Eulerian model can be used to predict concentration distributions of gaseous pollutants and particulate matters when there's an air cleaner operating and CFD simulation is an efficient tool to analyze personal ventilation; (2) the Exposure Reduction Effectiveness (ERE) index is effective for describing the removal effectiveness of room air cleaners in local zones as well as the room average.