The environmental sustainability of technological plants, which is a fundamental requirement for territorial planning, needs the development of different widening moments. First, of all it is necessary to consider the plant as a potential source of pollutant emissions and to verify that the best technologies have been used to limit these fluxes, taking into account economic restraints. Second, the effect of the release on air quality modification should be established, with reference to air quality in particular, in order to be able to make suitable comparisons with recognized standards. Finally, it is necessary to evaluate the pollutant dose that has an impact on the exposed subjects, and the risk that arises from this impact, taking into account both toxicological and epidemiological considerations. The description of this path, with reference to some real cases of substantial impact and public concern, can be considered a methodological outline for the required compatibility assessment.