The study objectives were to improve the understanding of the long-term variation of VOC emission
chromatograms of building materials and to develop a method to account for this variation in the
identification of individual sources of VOC emissions. This is of importance for the application of the
source identification method since materials age over time in real indoor environments. The method is
based on the mixed air sample measurements containing pollutants from multiple aged materials and the
emission signatures of individual new materials determined by PTR-MS. Three emission decay source
models were employed and evaluated for their ability to track the change of individual material emission
signatures by PTR-MS over a nine-month period. Nine building material specimens were studied in
a ventilated 50-L small-size chamber for their emissions individually for nine months, and also in
combination later. Chamber exhaust air was sampled by PTR-MS to construct a temporal profile of
emission signature unique to individual product type. The similar process was taken to measure mixture
emissions from multiple materials, which is for applying and validating the developed method for source
identification enhancement, considering the variation in long-term emission rates of individual VOCs.
Results showed that the proposed approach could predict the emission signatures of individual building
materials at a later time (9-month) with less than 6% difference variance, and hence indicated the
potential of the source identification method for aged materials in real indoor environments.