Some aspects of a number of different techniques for environmental decision support, in particular risk assessment (RA) and life-cycle assessment (LCA), are briefly discussed. The importance of a coherent framework, the use of common data sets, and harmonization of methods is emphasized. The latter leads to a discussion of a fundamental difference between techniques that assess continuous emission fluxes, like RA, and techniques that assess discrete emission pulses, like LCA. The question whether it is possible to apply the same types of impact assessment models is positively answered for most models. The implications are threefold: It is allowed to employ the much easier steady-state models in pulse-oriented techniques, there exist often postulated but not yet rigidly proven equivalency factors for use in e.g. life-cycle assessment, and it is possible to harmonize the models as used in pulse-oriented and in flux-oriented models.