Real-time data obtained with an atmospheric pressure chemical ionization mass spectrometer were used for both qualitative and quantitative evaluation of air cleaner performance. Differences among air cleaners were evaluated by performing ANOVA followed by a Bonferroni-normalized multiple comparison test on the average concentration of each analyte when the air cleaners were on and off. A mathematical model was developed and applied which permits air cleaner efficiencies and clean air delivery rates to be determined by performing a kinetic analysis of the real-time data for each analyte. This new method for determining clean air delivery rate is broadly applicable to any steady-state concentration data and does not require real-time data for application.