As a result of advances in the state of the art, industrial plants commissioned in the past no
longer meet the pertinent legal requirements. In order to comply with the new maximum values
for critical emissions, the law usually grants transition periods for existing plants that are liable
for approval. While, from a legal point of view, the duty to adapt arises as soon as the
applicable law takes effect, the literature sometimes also stipulates an economic causal
relationship in order for provisions to be formed