The Unites States Coast Guard have issued a Marine Safety alert 04-19 Confined Spaces: Silent & Invisible Killers. “This is a reminder that despite decades of work by to improve confined space entry by maritime safety organizations, training institutions, and vessel owners/operators, the risks have not been eliminated. This is illustrated by a recent casualty where three persons were asphyxiated while working onboard a laid-up Mobile Offshore Drilling Unit (MODU).  The full report can be read here  USCG Marine Safety Alert 04-19