Key Change - Recommendation to Mandatory CO₂ Measurement

We are reaching out to bring an important recent regulatory development to your attention that directly impacts enclosed space entry procedures and gas detection equipment onboard vessels.

The IMO has recently published Resolution MSC.581(110), introducing revised recommendations for enclosed space entry, with a particular focus on atmospheric testing and gas measurement.

🔍 Key Change: Carbon Dioxide (CO₂) Percentage Volume Measurement, also applicable in measurement within inert conditions (without background of oxygen or air)

Paragraph 7, “Testing the atmosphere”, introduces new expectations regarding carbon dioxide (CO₂) detection in enclosed spaces:

  • Gas detection equipment must be suitable for the cargo carried and capable of operating correctly even in oxygen-depleted atmospheres, including the ability to measure CO₂.

  • Prior to entry, steady readings must confirm CO₂ levels below 0.5% by volume (5,000 ppm).

  • Personnel entering enclosed spaces should be equipped with calibrated personal gas detectors capable of monitoring:

    • Oxygen (O₂)

    • Carbon dioxide (CO₂)

    • Flammable gases/vapours

    • Toxic gases (including CO)

    • Any additional gases identified in the risk assessment

⚠️ What This Means for Your Fleet

Most vessels currently operate with standard 4-gas detectors (e.g. LEL, O₂, CO, H₂S). These devices do not include CO₂ sensors and therefore do not fully meet the new recommendations outlined in MSC.581(110).

While this Resolution is voluntary at present, it is widely expected that the IMO will formally adopt these requirements at the next MEPC meeting in early 2026, at which point compliance will become mandatory.

📥 Free Downloads to Support Your Compliance Planning

To help you prepare, we are offering free downloadable resources, including:

  • A summary of MSC.581(110) and the enclosed space CO₂ requirements

  • A comparison guide showing current 4-gas vs. CO₂-enabled multi-gas detectors

  • A practical checklist to assess your fleet’s readiness

👉 [Download your free resources here]

ABS Regulatory News Confined Space Entry Download

If you would like to discuss how these changes affect your vessels, or explore CO₂-capable personal gas detection solutions, our team would be happy to assist.

Back to blog
1 3
View all