Existing general explicit mass transfer models for volatile organic compound emissions have been validated against experimental results from small test chambers. This study compared emission rates predicted by such models to observations from homes, large test chambers and full scale experiments. The comparison revealed that the examined explicit emission models could not simulate behaviour observed under real world conditions for the cases studied. It is hypothesised that the reasons for the observed discrepancies include that: (1) There is a shortage of detailed information on the actual physical conditions at the emitting surfaces under real world conditions. (2) The mathematics behind the explicit emission models does not allow such models to fully capture the dynamic behaviour of a system with varying temperature and relative humidity. (3) The assumption that change in the concentration in an emitting material is determined by diffusion alone, implicitly implying that generation is negligible, may not be valid outside small test chambers.