1. Member States shall take the necessary measures to ensure that competent authorities periodically reconsider and, where necessary, update permit conditions.
2. The reconsideration shall be undertaken in any event where:
((a))
the pollution caused by the installation is of such significance that the existing emission limit values of the permit need to be revised or new such values need to be included in the permit;
((b))
substantial changes in the best available techniques make it possible to reduce emissions significantly without imposing excessive costs;
((c))
the operational safety of the process or activity requires other techniques to be used;
((d))
new provisions of Community or national legislation so dictate.