The implementation of environmental quality objectives under secondary law in Germany is fraught with difficulties. This is particularly true for the application of environmental quality objectives as a criterion for the granting of permits for installations emitting pollutants (so-called impairment prohibitions). The following essay points out the difficulties as well as their reasons and it assesses whether the application of “irrelevance thresholds“ (study area limitation, de minimis thresholds) are in conformity with EU law. The justification of irrelevance thresholds is based on the thesis that impairment prohibitions under EU law consistently have a final structure that leaves room for Member States to concretise their provisions. The difficulties – and the partly irrational results – of the implementation of European environmental quality objectives in Germany can ultimately be seen as “homemade”.