This milestone was achieved along with other key outcomes at the 12th session of the Sub-Committee on Pollution Prevention and Response, which was held at IMO Headquarters in London from 27 to 31 January 2025. The meeting was chaired by Dr. Anita Mäkinen of Finland.

A summary of the meeting is included below:

Revised Action plan to address marine plastic litter from ships agreed 

The Sub-Committee agreed on the draft 2025 Action Plan to Address Marine Plastic Litter from Ships, with a view to its approval by the Marine Environment Protection Committee at its upcoming session (MEPC 83) on 7 to 11 April 2025.

The 2025 Action Plan was prepared following a revision of the initial Action Plan approved in 2018, taking into account actions that had been completed since its approval. The actions included in the draft 2025 Action Plan are set for completion by 2030 and aim at the following main outcomes:

• Reduction of the contribution from fishing vessels to marine plastic litter
• Reduction of shipping’s contribution to marine plastic litter
• Enhanced public awareness, education and seafarer training
• Improvement of the effectiveness of port reception facilities and treatment in reducing marine plastic litter
• Improved understanding of the contribution of ships to marine plastic litter
• Strengthened international cooperation

The Sub-Committee updated the timeframes for the expected completion of the actions, grouping them according to short-, mid-, long-term and continuous actions.

Carriage of plastic pellets by sea 

The draft 2025 Action Plan to Address Marine Plastic Litter from Ships includes a dedicated action for the development of mandatory measures to reduce the environmental risks of plastic pellets transported by sea in freight containers.

To inform future discussions on the legal framework for introducing such measures, the Sub-Committee developed a table outlining various considerations, including advantages, limitations and impacts relating to possible amendments to mandatory instruments linked to the carriage of plastic pellets by sea.

Reporting lost or discharged fishing gear 

The Sub-Committee continued discussions around setting up a database hosted by IMO, to be used for reporting abandoned or lost fishing gear. The accidental loss or other exceptional discharges or losses of fishing gear from ships are a significant contributor to plastic pollution in the ocean.

The Sub-Committee endorsed the recommendation that data to be reported to IMO to fulfil Objectives 1 to 3 of the IMO database (as agreed at PPR 11) should include: ship particulars (such as name, length and type of vessel), event particulars (such as the position where the fishing gear was lost or discharged, date and time of the incident) and details about the fishing gear in question, noting whether it is mandatory or voluntary information.

Member States and international organizations were invited to submit written proposals on the specifics of the agreed data to be reported to IMO to a future session of the Sub-Committee.

Guidance on in-water cleaning of ships’ biofouling agreed 

The Sub-Committee agreed to draft Guidance on in-water cleaning of ships’ biofouling, together with an associated draft MEPC circular, for approval by MEPC 83.

In-water cleaning is the removal of biofouling from a ship’s hull and niche areas while in the water. The draft guidance supports the 2023 Guidelines for the control and management of ships’ biofouling to minimize the transfer of invasive aquatic species (2023 Biofouling Guidelines). It provides guidance for the safe planning and execution of in-water cleaning operations, as well as the design and performance of in-water cleaning systems, while addressing risks to the environment and ship coatings.

2023 Guidelines for the development of the Inventory of Hazardous Materials – amendments approved 

The Sub-Committee approved draft amendments to the 2023 Guidelines for the development of the Inventory of Hazardous Materials and the associated draft MEPC resolution, with a view to adoption by MEPC 83 and implementation prior to the entry into force of the Hong Kong Convention on 26 June 2025.

The draft amendments to the 2023 Guidelines clarify the relevant threshold values in respect to cybutryne when samples are directly taken from the hull or when samples are taken from wet paint containers.

Black Carbon emissions in the Arctic 

The Sub-Committee discussed the concept of “polar fuels” as a category of fuels aimed at contributing to a reduction of the impact on the Arctic of Black Carbon emissions from international shipping. A proposal for including characteristics that would address challenges faced during oil spill response in cold water conditions was also considered.

The Sub-Committee invited Member States and international organizations to submit concrete proposals on the “polar fuels” concept to its next session (PPR 13), which could be supported by scientific studies and findings from Black Carbon measurement campaigns using the measurement reporting protocol set out in the Guidelines on recommendatory Black Carbon emission measurement, monitoring and reporting (resolution MEPC.394(82)).

Development of regulatory measures and instruments concerning the discharge of discharge water from Exhaust Cleaning Gas Systems (EGCS) 

The Sub-Committee continued discussions on developing possible regulatory provisions on limitations/restrictions of the discharge of discharge water from EGCS, also known as scrubbers, having noted that the consideration of a global total ban on the use of EGCS was outside the scope of this output.

The Sub-Committee invited interested Member States and international organization to submit new concrete proposals on regulatory measures addressing discharges of EGCS discharge water to PPR 13, reflecting latest available data and taking into account work conducted so far.

Emission factors for use in the environmental risk assessment of the discharge water from EGCS 

The Sub-Committee finalized terms of reference for the GESAMP Task Team on Exhaust Gas Cleaning Systems (EGCS), for approval by MEPC 83, and invited MEPC 83 to reestablish the GESAMP Task Team to carry out the following activities:

• Compare various methods for achieving a representative set of emission factors with universal geographic application. Emission factors enable ports and port States to complete a key step in developing EGCS-related environmental risk assessments.
• Evaluate best practices for developing the data sets and methods.
• Evaluate considerations for calculating emission factors.
• Propose a standard methodology for development of the data sets and calculation of the emission factors for a representative and universal set of emission factors, including best practices.
• Report on any sets of emission factors determined using the methodology developed by the GESAMP Task Team on EGCS.
• Submit a report on its findings to PPR 13.

The Sub-Committee requested MEPC 83 to extend the target completion year of this output (1.23) to 2026.

Guidelines on Selective Catalytic Reduction (SCR) systems approved 

The Sub-Committee approved the draft 2025 Guidelines on Selective Catalytic Reduction (SCR) Systems and the associated draft MEPC resolution, for adoption by MEPC 83. SCR systems are a type of device used to reduce NOx emissions, in line with section 2.2.5 of the NOx Technical Code 2008 (NTC 2008).

The draft 2025 SCR Guidelines update the 2017 SCR Guidelines to remove ambiguities and ensure consistent application, while reflecting the latest developments in the industry.

The approved draft MEPC resolution further states that the Guidelines will be kept under review in light of experience gained with their application, with a view to incorporating them into the NOx Technical Code 2008.

Interim guidance on the carriage of blends of biofuels and MARPOL Annex I cargoes by conventional bunker ships agreed 

The Sub-Committee agreed to draft Interim guidance on the carriage of blends of biofuels and MARPOL Annex I cargoes by conventional bunker ships, along with the accompanying draft MEPC circular. These will be submitted to MEPC 83, with a view to approval.

The guidance allows conventional bunker ships certified for carriage of oil fuels under MARPOL Annex I to transport blends of not more than 30% by volume of biofuel, as long as all residues or tank washings are discharged ashore, unless the oil discharge monitoring equipment (ODME) is approved for the biofuel blend(s) being shipped.

Revision of MARPOL Annex IV to improve the lifetime performance of sewage treatment plants  

The Sub-Committee re-established the Correspondence Group on Revision of MARPOL Annex IV and Associated Guidelines, to progress the work intersessionally and report back to PPR 13.

Key tasks in the Correspondence Group’s terms of reference include:

• further develop the draft revised MARPOL Annex IV with regard to the Sewage Record Book (SRB) and Sewage Management Plan (SMP), with a view to finalization at PPR 13;
• continue the development of the draft revised MARPOL Annex IV apart from the work above, as appropriate;
• further develop draft amendments to the 2012 Guidelines on implementation of effluent standards and performance tests for sewage treatment plants (Type Approval Guidelines);
• further develop the draft guidelines on the implementation of MARPOL Annex IV for sewage treatment plants (Implementation Guidelines);
• develop draft guidance on obtaining data with regard to the quality of treated sewage effluent.