Question 1

A risk assessment for a particular enclosed space concludes there is negligible risk of CO2 presence. Under MSC.581(110), is the crew still obliged to measure CO2 during entry?

Accepted Answer

Not necessarily under the IMO recommendation itself — if the risk assessment shows negligible CO2 risk, CO2 measurement during entry is not required, but some flag Administrations interpret this differently and may mandate CO2 measurement regardless, so the company must check applicable flag Administration notices This is an area of genuine regulatory nuance: para. 8.2 ties CO2 measurement requirement to the outcome of the risk assessment, but the ABS guidance specifically flags that flag Administrations may take a stricter interpretation and require CO2 measurement irrespective of the risk assessment outcome — owners/managers must check flag notices rather than assume the IMO baseline applies unmodified.

Question 2

Under MSC.581(110), what is the maximum acceptable CO2 reading (by volume) before an enclosed space can be considered safe for entry?

Accepted Answer

Less than 0.5% by volume (5,000 ppm) Para. 7.4 sets the CO2 exposure limit at below 0.5% by volume (5,000 ppm) before entry; if this is not achieved, the space remains unsafe. CO2 is now explicitly addressed as a major asphyxiation hazard alongside oxygen depletion.

Question 3

Under the revised recommendations, is single-person entry into an enclosed space ever permitted?

Accepted Answer

No — the company must ensure single-person entry into an enclosed space is not permitted Para. 3.11 explicitly prohibits single-person entry into an enclosed space under any circumstances covered by the recommendation.