I think it should go like this:
1) Hazards that fall into a low severity risk, are considered generally
acceptable and will not require further analysis.
2) The one with the medium severity should be looked over and find the problem and mitigate it.
3) Hazards that fall into a high severity risk, are generally unacceptable. If
hazards at these level cannot be further mitigated to the point of
falling into an acceptance zone (low or medium), a formal risk/ benefit analysis
shall be performed and documented.