Examples of the application of k0 standardized instrumental neutron activation analysis (k0-INAA) to aerosols and biological monitors in the last 10 years at Instituto Tecnológico e Nuclear (ITN) are given. As an analytical technique, INAA, in association with the k0 method was applied to these materials in four different projects, aiming at monitoring concentrations of heavy metals and others elements in the atmosphere in the Portuguese territory. In these studies we analysed the lichen Parmelia sulcata Taylor and olive tree bark as monitors as well as aerosol samples. For each project some representative results are presented, followed by a discussion of the application of this technique to environmental studies.