IMO Amendment For MARPOL ANNEX VI Aims To Reduce Air Pollution From Ships

By February 14, 2023 No Comments

At the MEPC 76 (Marine Environment Protection Committee) in June 2021 the adoption of Amendments to MARPOL Annex VI was agreed upon. The amendments came into force in November 2022 and from January 2023 it is now mandatory for all ships to calculate their Energy Efficiency Ship Index EEXI (see below) and evidence of carbon intensity reduction must be recorded in a new section of the vessel’s existing management system for carbon intensity.

The International Maritime Organization (IMO) amendment for MARPOL Annex VI is a regulation that sets out new requirements for reducing the emissions of sulfur oxides (SOx) from ships. This includes a reduction of the global limit for sulfur content in marine fuels from 3.5% to 0.5%, the limit of which applies to all ships operating outside designated emission control areas (ECAs). The ECAs already have lower sulfur limits, with the limit set at 0.1%.  

 The overall IMO target for 2030 is to reduce Co2 emissions per unit of ‘transport-work’ as an average across international shipping, by at least 40% (compared to 2008 levels).

Ship owners must now take steps to reduce emissions from their vessels


The EEXI sets out mandatory carbon intensity reduction targets for ships that are already in operation, and it aims to help reduce the carbon footprint of the shipping industry by lowering emissions from existing vessels.

The EEXI is calculated based on a ship’s technical characteristics, such as its size, age, and engine power, and it takes into account the ship’s fuel consumption and CO2 emissions. The EEXI will be used to determine whether a ship is compliant with the required carbon intensity reduction targets.

By setting mandatory carbon intensity reduction targets for existing ships, the EEXI is expected to encourage ship owners to take measures to improve the energy efficiency of their vessels. This could include implementing measures such as engine upgrades, hull coatings, and exhaust gas cleaning systems.

The EEXI can also help to improve the competitiveness of the shipping industry. More energy-efficient vessels are likely to have lower operating costs, which can help to reduce shipping rates and improve profitability for ship owners.


The CII is a measurement of a ship’s carbon emissions per unit of transport work, such as the amount of cargo or passengers carried. It is intended to provide a standardised and comparable way to assess the carbon intensity of ships and their operations.

The CII will be used to determine a ship’s compliance with the IMO’s mandatory carbon reduction targets, which aim to reduce the carbon intensity of international shipping by at least 40% by 2030 compared to 2008 levels. The CII will also be used to develop a rating system for ships, similar to the Energy Efficiency Design Index (EEDI) for new ships.

The CII is expected to help reduce carbon emissions from ships in several ways. First, it will provide a transparent and comparable way to measure and compare the carbon intensity of different ships and their operations. This will help to identify the most carbon-efficient ships and encourage ship owners to improve the energy efficiency of their vessels.

Second, the CII will provide a clear and measurable target for ship owners to achieve in order to comply with the IMO’s carbon reduction targets. This will encourage the adoption of measures to improve the energy efficiency of ships, such as engine upgrades, hull coatings, and exhaust gas cleaning systems, which can reduce fuel consumption and emissions.

Third, the CII will encourage the use of low-carbon or zero-carbon fuels, such as biofuels, hydrogen, or ammonia. By using these fuels, ships can significantly reduce their carbon emissions, helping to achieve the IMO’s carbon reduction targets.

How Ship Owners Can Meet The Requirements

Ship owners can address pollution prevention by implementing best practices for environmental management. This includes implementing an environmental management system (EMS) that outlines procedures for reducing waste, conserving energy, and minimizing pollution. An EMS can help a ship owner identify potential environmental risks and put in place measures to prevent and mitigate those risks. In addition, ship owners can invest in technology and equipment that can reduce emissions and improve energy efficiency, such as exhaust gas cleaning systems, low sulfur fuel, and energy-efficient engines. Alternatively, they can use alternative fuels such as liquefied natural gas (LNG), which has a lower sulfur content

Another key aspect of pollution prevention from ships is crew training and awareness. Ship owners should provide their crew with training on environmental protection and pollution prevention, as well as safety procedures for handling hazardous materials. Crew members should be aware of the proper handling and disposal of waste materials and understand the importance of preventing pollution. Additionally, ship owners should encourage crew members to report any incidents of pollution or potential environmental hazards so that corrective action can be taken.

Effective communication with port authorities and other stakeholders is also important for pollution prevention. Ship owners should inform port authorities of their vessels’ environmental management practices and procedures, as well as any potential environmental risks. By working collaboratively with port authorities and other stakeholders, ship owners can develop effective strategies for pollution prevention that benefit both the environment and the shipping industry.

Here is a summary of 10 actions ship owners can take to prevent or reduce air pollution from ships:

1. Switch to low-sulfur fuel: This can significantly reduce sulfur oxide emissions, which are a major contributor to air pollution.

2. Install exhaust gas cleaning systems: These systems can reduce emissions of sulfur oxides, nitrogen oxides, and particulate matter.

3. Optimize engine performance: Proper maintenance and tuning of engines can improve fuel efficiency and reduce emissions.

4. Use shore power: When in port, ships can use shore power instead of running their engines, which can significantly reduce emissions.

5. Implement speed reduction measures: Reducing ship speed can reduce fuel consumption and emissions.

6. Improve aerodynamics: Design modifications such as bulbous bows and hull coatings can improve fuel efficiency and reduce emissions.

7. Retrofit existing vessels: Installing new equipment such as scrubbers or upgrading engines can reduce emissions from older vessels.

8. Use alternative fuels: Renewable fuels such as biofuels or hydrogen can be used as an alternative to fossil fuels, reducing emissions.

9. Adopt best practices for energy management: This can include measures such as optimising ventilation, lighting, and HVAC systems to improve energy efficiency and reduce emissions.

10. Train crew members: Proper training can help crew members understand the importance of air pollution prevention and reduce the likelihood of accidental emissions.

The implementation of the IMO amendment for MARPOL Annex VI is expected to have significant benefits for the environment and overall human health. By reducing the emissions of sulfur oxides and other harmful pollutants from ships, it will help to improve air quality and help to address the contribution of the shipping industry to global greenhouse gas emissions.

Vassallo Associates can advise on all aspects of the environmental management of your vessel. Contact us today for a no-obligation consultation.

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