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Maritime Insights and Knowledge-hub Understanding MARPOL

Understanding MARPOL

IMO & MARPOL Sep. 17, 2024
Understanding MARPOL

MARPOL is one of the International Maritime Organisation’s (IMO) three core conventions, supporting its efforts to improve the safety and security of international shipping and to prevent pollution from ships.

The International Convention for the Prevention of Pollution from Ships (MARPOL) was adopted by the United Nations agency IMO in 1973. Five years later, the Protocol of 1978 was adopted by IMO, and the combined instrument entered into force in 1983.

The Convention includes regulations aiming at preventing and minimising different types of impact to the marine environment from ships operating around the world. IMO regulations only apply to ships flying the flag of one of its 176 Member States.

MARPOL has been updated through amendments over the years and currently includes six technical Annexes, each addressing different pollutants.

In a series of articles featured on this page, we will take a deep dive into MARPOL Annex VI, which originally aimed at reducing air pollution from shipping, and in recent years has been updated significantly to include the reduction of GHG emissions from shipping.

Learn more:

• International Maritime Organisation (IMO)

• International Convention for the Prevention of Pollution from Ships (IMO)

FAQ MARPOL

  • What is MARPOL Annex VI?

    Annex VI, titled ‘Prevention of Air Pollution from Ships,’ is a part of the International Convention for the Prevention of Pollution from Ships (MARPOL). Adopted in 1997 and enforced from 2005, it sets limits on sulphur oxide (SOx) and nitrogen oxide (NOx) emissions from ship exhausts to minimize air pollution.

  • Why are SOx and NOx emissions specifically targeted in MARPOL Annex VI?

    SOx and NOx are identified as the two main pollutants from ship emissions, significantly impacting air quality. Limiting these emissions is crucial for reducing air pollution and protecting environmental and human health, especially in densely populated coastal areas.

  • What are the emission control areas (ECAs) mentioned in MARPOL Annex VI?

    ECAs are specific sea areas near coastlines under MARPOL Annex VI where stricter emission standards are applied to further decrease SOx and NOx emissions from ships. These areas include the Baltic Sea, North Sea, North American areas (West and East), the Hawaii Area, and the U.S. Caribbean Area.

  • How do ships comply with the SOx content limits set by MARPOL Annex VI?

    Ships can comply with the SOx content limits by using fuels with lower sulphur content, such as ultra-low sulphur fuel oil or LNG, or by installing exhaust gas cleaning systems, known as scrubbers, that remove pollutants from exhaust gases.

  • What measures are in place to reduce NOx emissions under MARPOL Annex VI?

    MARPOL Annex VI imposes NOx limits through Tier I, II, and III standards, which can be met through various technologies such as combustion optimisation and dedicated emission control technologies like selective catalytic reduction.

  • How is compliance with MARPOL Annex VI monitored and enforced?

    Compliance is monitored through certificates like the Engine International Air Pollution Prevention (EIAPP) certificate for NOx, and the International Air Pollution Prevention (IAPP) Certificate for SOx. Enforcement and penalties for non-compliance are determined by individual Parties to MARPOL, such as flag and port States.

  • How does MARPOL Annex VI relate to decarbonisation?

    A 2021 amendment to MARPOL Annex VI requires ships to calculate their Energy Efficiency Existing Ship Index (EEXI) and begin data collection for reporting their annual operational carbon intensity indicator (CII) and CII rating (A to E). These measures aim to promote energy efficiency and the use of low-carbon fuels in the shipping industry.

  • How do ships improve their carbon intensity (CII) rating under the new amendment?

    Ships can improve their carbon intensity rating (A to E) by reducing GHG emissions through various methods such as using low-carbon fuels, optimising speed, and installing solar/wind auxiliary power. High-rated ships may receive incentives to further motivate emissions reduction.

  • What impact does MARPOL Annex VI have on the shipping industry?

    MARPOL Annex VI mandates significant changes in ship operations, including the use of cleaner fuels, installation of emission reduction technologies, and compliance with stringent emission standards. It also pushes the industry towards decarbonisation and energy efficiency improvements.

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