On 3 December 2025, IMO Resolution MSC.581(110) replaced the former A.1050(27), tightening the requirements for entering enclosed spaces on board ships, one of the leading causes of fatal accidents at sea.
The most important change is that CO₂ is now treated as a primary hazard and must be measured separately, staying below 0.5% (5,000 ppm) before entry. Oxygen must be at least 20.9%, toxic and flammable gases must stay within strict limits, and every person entering must carry a calibrated personal gas detector for continuous monitoring. Single-person entry is prohibited, and ships must keep a register of enclosed spaces.
In practice this means many vessels still relying on standard 4-gas detectors without CO₂ need to upgrade. At least two sets of portable gas detection equipment are required on board, and four for high-risk cargoes such as coal and wood pellets.
De Wolf helps you comply. We supply MSC.581(110)-ready multi-gas detectors that measure O₂, CO₂, flammable and toxic gases, delivered with the relevant certificates such as IMO, MED, SOLAS and Classification Society approval. We also support calibration, bump testing and fleet-readiness advice so your crew stays safe and your documentation stays inspection-ready.
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Official source: IMO Resolution MSC.581(110) · Full resolution text (overheid.nl)