If a regional on-scene commander or the National On-Scene Commander decides that it is appropriate for a regional council or the Authority, as the case may be, to take action in respect of a marine oil spill, the principal objective of that on-scene commander shall be to—a) prevent further pollution from the marine oil spill; andb) contain and clean up the oil spill in accordance with the relevant regional marine oil spill contingency plan or the National Oil Spill Contingency Plan, as the case may be,—in such a way that does not cause any unreasonable danger to human life or cause an unreasonable risk of injury to any person.