The International Maritime Organisation (IMO) has published Resolution MSC.581(110), which provides revised recommendations for entering enclosed spaces aboard ships. The IMO’s 34th Assembly meeting in December 2025, revoked resolution A.1050(27), as of the date of adoption of resolution MSC.581(110).

SOLAS Regulations

Mandatory SOLAS regulations are already in place to protect seafarers who need to enter enclosed spaces. They include:

• SOLAS Regulation III/19.3.6: This requires enclosed space entry and rescue drills to be planned and conducted in a safe manner, taking into account, as appropriate, the guidance provided in the recommendations developed by the IMO.
• SOLAS Regulation XI-1/7: This requires the carrying of atmosphere testing instruments for enclosed spaces.
• SOLAS Chapter IX and International Safety Management Code: These require safety management systems for the safe operation of ships.

Significant Changes for Enclosed Spaces Safety

The measures in Resolution MSC.581(110) include clarifying the responsibilities for crew safety and training, reinforcing the use of portable gas detection equipment, updating enclosed space rescue procedures and maintaining a ship-specific enclosed spaces register on board.

The guidelines include significant changes to the following sections:

Section 2: Definitions
This includes new definitions for ‘Connected Space’, ‘Adjacent Space’, ‘Trapped Hazardous Atmosphere’ and ‘Enclosed Space Register’.

Section 3: Safety Management for Entry into Enclosed Spaces
This is substantially revised and includes a new requirement to carry an ‘Enclosed Space Register’.

Section 4: Identification of the Hazards and Assessment of Risk
This is revised to include further information on assessing risk, including a new requirement for an ‘Enclosed Space Emergency Response Plan’.

Section 5: Authorisation of Entry
This includes new requirements relating to permits for entry.

Section 6: General Precautions
This includes new requirements related to accessing enclosed spaces and training of personnel.

Section 7: Testing the Atmosphere
This includes new requirements related to gas detection equipment required on board, including devices for testing CO₂. It states that the gas detection equipment should be appropriate for the cargo that the ship has carried and is carrying.

Section 10: Hazards Related to Specific Types of Cargo
This includes new requirements for carriage of solid bulk cargo, hazards related to steel, specific dangers associated with CO₂ and information on acceptable and unacceptable levels of gases.

Section 11: Action to be Taken in the Event of an Emergency
This section is substantially revised.

Appendices
New appendices have been added:

• Example of Enclosed Space Emergency Response Plan
• Example of an Enclosed Space Warning Sign
• Example of a Simplified Ship Space Diagram to be Placed at the Ship’s Access Point
• Information on Acceptable and Unacceptable Levels of Gases

What shipowners and ship operators should do now

Review and amend shipboard procedures and equipment to ensure compliance with the revised recommendations of IMO Resolution MSC.581(110), taking into account the requirements of the vessel’s flag Administration.