Maritime Compliance: IMO Revised Recommendations on Enclosed Space Entry

(www.MaritimeCyprus.com) The objective of the IMO’s Revised Recommendations is to enhance safety during enclosed space entry, reduce persistent fatalities, and strengthen the process of hazard identification, risk assessment, and crew empowerment.

These Recommendations may be applied to all ship types and provide guidance for ship operators, crew, port workers, and other shore personnel involved in operations on board.

The IMO recognizes that many enclosed space accidents stem from a failure to systematically identify hazards, assess risks, and implement appropriate entry procedures. Investigations further highlight that the complex structural arrangements of certain spaces can hinder ventilation, illumination, and safe movement. Organizational leadership ashore and on board plays a critical role, particularly in empowering personnel to stop unsafe operations and make informed decisions to prevent accidents. Recent casualty trends underscore the ongoing need for improved risk assessment practices and increased awareness of CO₂-related hazards.

The IMO Sub-Committee on Carriage of Cargoes and Containers (CCC 10) developed amendments to Resolution A.1050(27) in 2024 to combat the continued loss of life resultant from the hazards of enclosed space entry. These revisions were adopted by the 110th session of the Maritime Safety Committee on 27 June 2025 through Resolution MSC.581(110), and finally endorsed by the 34th Assembly on 3 December 2025, which formally revoked A.1050(27). The new resolution introduces a more comprehensive and structured approach to enclosed space entry, including new definitions, strengthened atmospheric testing requirements, enhanced responsibilities toward shore personnel, and updated emergency preparedness measures.

ENCLOSED SPACE REGISTER, PROCEDURES, FORMS AND PLANS

The example of the Enclosed Space Register was removed from the revised recommendation, leaving it to the company to develop its own registry, along with the risk assessment, forming the basis for the development of the enclosed space contingency plan.

The revised recommendations also contain an updated example of an Enclosed Space Entry Permit, and an Enclosed Space Emergency Response Plan.

KEY POINTS TO CONSIDER

The hazards from lack of Oxygen (O₂) and the build-up of gases such as Carbon Dioxide (CO₂) and Carbon Monoxide (CO) are well known, but their relationships are not always fully understood. More recent studies show that, as well as Oxygen levels, the levels of Carbon Dioxide and Carbon Monoxide should be checked before entry is made to any enclosed space or adjacent connected space. To emphasize this, CO₂ is now explicitly included in the revised Recommendation.

CO₂ is a potent asphyxiant and can cause rapid loss of consciousness and death. Its behavior in cargo spaces justifies CO₂ monitoring before and during enclosed space entry, in addition to CO and other toxic gases.

The following points provide additional clarification on specific elements of the revised Recommendations and address common questions regarding atmospheric monitoring, cargo-related hazards and gas detection equipment.

Risk Assessment

A risk assessment should be conducted by the competent person prior to opening an enclosed space. The competent person should be appropriately trained. This training should include adequate theoretical knowledge and practical experience; allowing them to make an informed judgement of the space to be opened/entered. The risk assessment should assess the likelihood of a dangerous atmosphere being present or subsequently developing within the space along with any other potential hazards in the space as identified in the vessel’s Enclosed Space Register, and the need to ventilate adjacent spaces.

CARGO-RELATED GAS EMISSION RISKS

There is no general published list of cargoes that may produce flammable, toxic, corrosive or asphyxiant gases (such as CO₂). Instead, hazard information should be derived from:

• the shipper’s declaration
• Safety Data Sheets (SDS)
• the IMDG Code
• the IMSBC Code (including individual cargo schedules)
• the IBC Code
• the IGC Code

The revised Recommendations (para. 10.3.3) highlight several cargoes that have caused fatalities due to fire, explosion or asphyxiation. These include coal; wood products; wood chips/pellets; metal sulfide concentrates; ferrous materials; seed cake cargoes; scrap metal; and certain grain/timber cargoes. It should be noted that these cargoes may be classified as group A or group C by the IMSBC Code.

NUMBER OF PORTABLE GAS DETECTORS

MSC.581(110) does not change existing SOLAS or IGC Code requirements regarding the quantity of portable gas detectors. However, Paragraph 7.3 reinforces that all ships must carry at least two sets of gas detection equipment as per SOLAS XI-1/7. Ships carrying cargoes capable of generating hazardous vapor and requiring regular entry must carry two additional sets. Moreover, detectors must be supplied with sufficient spares and calibration means and may use flexible hoses or fixed sampling lines to test remote areas safely. Gas detection capabilities of portable gas detectors The requirements remain consistent with previous minimum requirements as detailed in MSC.1/Circ.1477. Paragraph 8.2 details that personal detectors should measure:

• oxygen (O₂)
• any other gases identified in the risk assessment o carbon dioxide (CO₂)
• toxic gases, including carbon monoxide (CO)
• flammable gases or vapors (LEL).

For more details, click below to download a summary of these recommendations:

Source: IMO