Disclosed herein are methods for measuring the concentration of volatile air treatment chemicals in the air. These methods can be used to evaluate the effectiveness of, and/or optimize, dispensers that dispenses a volatile air treatment chemical into a test area. One runs side by side sampling of air using both sorbent tube and solid phase micro extraction fiber collectors to develop a correlationcurve between air treatment chemical concentration results from the sorbent tube sampling and amount readings from the SPME sampling. One then uses SPME collectors to measure in a passive manner theperformance of the volatile dispensers.