MARPOL Annex VI: Prevention of Air Pollution from Ships

The International Convention for the Prevention of Pollution from Ships (MARPOL) is the cornerstone of global efforts to reduce pollution from maritime activities. Among its six technical annexes, MARPOL Annex VI – Prevention of Air Pollution from Ships—plays a critical role in limiting harmful airborne emissions from vessels and promoting cleaner, more sustainable shipping practices.

First adopted in 1997 and entering into force in 2005, Annex VI sets international standards to control emissions of sulfur oxides (SOx), nitrogen oxides (NOx), volatile organic compounds (VOCs), and ozone-depleting substances (ODS). These pollutants contribute to acid rain, respiratory problems, global warming, and the degradation of marine ecosystems.

In response to the growing challenges of climate change and maritime air pollution, Annex VI has undergone several amendments to incorporate advanced emission controls and energy efficiency measures. Notable additions include the Energy Efficiency Design Index (EEDI) for new ships and the Ship Energy Efficiency Management Plan (SEEMP), both aimed at reducing greenhouse gas emissions and fuel consumption.

Through the leadership of the International Maritime Organization (IMO) and its member states, Annex VI has become a powerful regulatory tool to curb ship-based air pollution and advance environmental protection. With over 50,000 commercial ships operating globally, compliance with Annex VI is now essential for ensuring cleaner air, healthier coastal communities, and a sustainable future for international shipping.

As of December 2024, the IMO has introduced several significant updates to strengthen Annex VI, including stricter fuel standards, expanded Emission Control Areas (ECAs), and enhanced carbon intensity reporting requirements. The updated structure of MARPOL Annex VI reflects the shipping industry’s accelerating shift toward low-emission, energy-efficient operations in line with international climate goals.

Annex VI

Chapter 1 – General

Regulation 1: Application
Regulation 2: Definitions
Regulation 3: Exceptions and Exemptions
Regulation 4: Equivalents

Chapter 2 – Survey, Certification, and Means of Control

Regulation 5: Surveys
Regulation 6: Issue or Endorsement of a Certificate
Regulation 7: Issue or Endorsement of a Certificate by Another Party
Regulation 8: Form of Certificate
Regulation 9: Duration and Validity of Certificate
Regulation 10: Port State Control on Operational Requirements
Regulation 11: Detection of Violations and Enforcement
Regulation 12: Requirements for Platforms and Drilling Rigs

Chapter 3 – Requirements for Control of Emissions from Ships

Regulation 13: Nitrogen Oxides (NOₓ)
Regulation 14: Sulphur Oxides (SOₓ) and Particulate Matter
Regulation 15: Volatile Organic Compounds (VOCs)
Regulation 16: Shipboard Incineration
Regulation 17: Reception Facilities
Regulation 18: Fuel Oil Availability and Quality

Chapter 4 – Regulations on Energy Efficiency for Ships

Regulation 19: Application
Regulation 20: Attained Energy Efficiency Design Index (Attained EEDI)
Regulation 21: Required Energy Efficiency Design Index (Required EEDI)
Regulation 22: Ship Energy Efficiency Management Plan (SEEMP)
Regulation 22A: Collection and Reporting of Ship Fuel Oil Consumption Data
Regulation 23: Attained Energy Efficiency Existing Ship Index (Attained EEXI)
Regulation 24: Required Annual Operational Carbon Intensity Indicator (Required Annual Operational CII)
Regulation 25: Operational Carbon Intensity Rating
Regulation 26: Ship Operational Carbon Intensity Plan
Regulation 27: Verification of Ship Fuel Oil Consumption Data and Operational Carbon Intensity
Regulation 28: Annual Reporting to the Organization and Record Requirements

Chapter 5 – Verification of Compliance with the Provisions of This Annex

Regulation 29: Verification of Compliance

Notable Amendments:

Mediterranean Sea Emission Control Area (ECA): Effective 1 May 2025, the Mediterranean Sea is designated as an ECA for sulphur oxides (SOₓ) and particulate matter, requiring ships to use fuel oil with a sulphur content not exceeding 0.10% m/m or to employ equivalent methods to reduce emissions.

Bunker Delivery Note (BDN) Requirements: From 1 May 2024, the BDN must include the flashpoint of the fuel oil or a statement confirming that the flashpoint has been measured at or above 70°C, enhancing safety and compliance verification.

Carbon Intensity Indicator (CII) Reporting: Amendments to Appendix IX require the inclusion of attained and required CII values, the CII rating, and the attained Energy Efficiency Existing Ship Index (EEXI) in data submitted to the IMO Ship Fuel Oil Consumption Database, effective 1 May 2024.

These amendments reflect the IMO’s ongoing commitment to reducing air pollution and greenhouse gas emissions from international shipping, promoting environmental protection and energy efficiency.

Chapter 1 – General (MARPOL Annex VI)

Regulation 1 – Application
Specifies the scope of Annex VI, outlining its applicability to all ships, fixed and floating platforms, and drilling rigs, except where specific exemptions are granted.

Regulation 2 – Definitions
Provides clear definitions for key terms used throughout Annex VI, including “Emission Control Areas (ECAs),” “Nitrogen Oxides (NOx),” “Sulphur Oxides (SOx),” and “Energy Efficiency Design Index (EEDI).”

Regulation 3 – Exceptions and Exemptions
Details scenarios where the requirements of Annex VI do not apply, such as emergencies or cases where compliance is impracticable, along with exemptions for specific ship types or operations under agreed conditions.

Regulation 4 – Equivalents
Allows for the use of alternative methods or technologies that achieve equivalent emission reductions, provided they are approved by the Administration.

This chapter establishes the foundation for interpreting and applying the provisions of Annex VI.

Chapter 2 – Survey, Certification, and Means of Control (MARPOL Annex VI)

Regulation 5 – Surveys
Requires ships to undergo specific surveys (initial, renewal, annual, intermediate) to ensure compliance with Annex VI provisions regarding emissions and energy efficiency.

Regulation 6 – Issue or Endorsement of a Certificate
Details the process for issuing the International Air Pollution Prevention (IAPP) Certificate after successful completion of required surveys.

Regulation 7 – Issue or Endorsement of a Certificate by Another Party
Allows certificates to be issued or endorsed by a Party to MARPOL other than the ship’s flag state, with mutual agreement.

Regulation 8 – Form of Certificate
Specifies the format and information required for the IAPP Certificate to ensure consistency and uniformity.

Regulation 9 – Duration and Validity of Certificate
Defines the validity period of certificates and the conditions under which they remain valid or are invalidated (e.g., modifications, survey failures).

Regulation 10 – Port State Control on Operational Requirements
Grants authorities the right to inspect ships in ports to verify compliance with operational requirements of Annex VI.

Regulation 11 – Detection of Violations and Enforcement
Establishes mechanisms for identifying, reporting, and enforcing penalties for violations of air pollution prevention measures.

Regulation 12 – Requirements for Platforms and Drilling Rigs
Extends Annex VI requirements to cover emissions from fixed and floating platforms and drilling rigs, ensuring they meet compliance standards.

This chapter ensures robust systems for monitoring, verifying, and enforcing compliance with Annex VI regulations.

Chapter 3 – Requirements for Control of Emissions from Ships (MARPOL Annex VI)

Regulation 13 – Nitrogen Oxides (NOx)
Sets limits on NOx emissions based on engine type and installation date, categorized into Tiers (Tier I, II, III) with increasingly stringent limits for Emission Control Areas (ECAs).

As of the end of 2022, four established NECAs exist: the Baltic Sea, the North Sea, the North American ECA, and the United States Caribbean Sea ECA. By implementing more stringent NOx emission standards within these areas, Regulation 13 contributes to improving air quality and protecting sensitive marine ecosystems.

Regulation 14 – Sulphur Oxides (SOx) and Particulate Matter
Imposes limits on the sulphur content in fuel oil used onboard ships to reduce SOx emissions and associated particulate matter. Tighter limits apply in ECAs (0.10% sulphur) compared to the global limit (0.50% sulphur).

Regulation 15 – Volatile Organic Compounds (VOCs)
Requires controls to minimize VOC emissions from tankers during loading, storing, and transportation of crude oil. Ports and terminals are also encouraged to provide VOC management plans.

Regulation 16 – Shipboard Incineration
Prohibits incineration of certain substances (e.g., polychlorinated biphenyls, cargo residues) onboard ships and requires incinerators to meet specified performance standards. MARPOL Annex VI regulates shipboard incineration to reduce harmful emissions, including SOx, NOx, dioxins, and particulate matter. It prohibits incineration of specific materials, such as cargo residues, PCBs, heavy metal-laden garbage, halogenated petroleum products, sewage sludge, and sludge oil. Incineration is also banned in ports, harbours, estuaries, and Emission Control Areas (ECAs). Ship incinerators must meet approved design and operational standards to minimize environmental impact.

Regulation 17 – Reception Facilities
Mandates that ports and terminals provide adequate facilities for the reception of ship-generated waste, including residues from exhaust gas cleaning systems (scrubbers).

Regulation 18 – Fuel Oil Availability and Quality
MARPOL Annex VI mandates the use of safe, high-quality fuel oil onboard ships to ensure efficient, environmentally responsible operations and prevent safety risks. Fuel suppliers must provide a “Bunker Delivery Note” (BDN) detailing sulfur content, density, viscosity, and other key characteristics, adhering to ISO 8217:2017 or later standards. Regulation 15 prohibits fuel oil with excess sulfur, inorganic acid, or used lubricants, ensuring compliance and minimizing environmental impact.

These regulations aim to reduce emissions from ships and mitigate their environmental impact, particularly in ECAs and sensitive regions.

Chapter 4 – Regulations on Energy Efficiency for Ships (MARPOL Annex VI)

Regulation 19 – Application
Defines the scope of energy efficiency measures, applying to specific ship types and sizes engaged in international voyages.

Regulation 20 – Attained Energy Efficiency Design Index (Attained EEDI)
Requires new ships to calculate their attained EEDI, reflecting the ship’s energy efficiency performance and adherence to regulatory standards.

Regulation 21 – Required Energy Efficiency Design Index (Required EEDI)
Sets minimum energy efficiency standards (Required EEDI) for new ships, becoming stricter over time to encourage design improvements.

Regulation 22 – Ship Energy Efficiency Management Plan (SEEMP)
Mandates ships to develop and implement a SEEMP, outlining operational measures to improve energy efficiency and reduce greenhouse gas emissions.

Regulation 22A – Collection and Reporting of Ship Fuel Oil Consumption Data
Introduces a mandatory system for collecting and reporting ship fuel oil consumption data, including information on distance traveled and cargo carried.

Regulation 23 – Attained Energy Efficiency Existing Ship Index (Attained EEXI)
Requires existing ships to calculate and comply with the Attained EEXI, an equivalent to the EEDI, to improve energy efficiency standards for older vessels.

Regulation 24 – Required Annual Operational Carbon Intensity Indicator (Required Annual Operational CII)
Establishes targets for annual carbon intensity reductions, measured as CO₂ emissions per unit of transport work (e.g., gram CO₂ per ton-mile).

Regulation 25 – Operational Carbon Intensity Rating
Assigns annual carbon intensity ratings (A to E) based on the ship’s operational CII, with poor ratings triggering corrective actions.

Regulation 26 – Ship Operational Carbon Intensity Plan
Requires ships to maintain an operational plan outlining measures to achieve and maintain compliance with CII targets and improve ratings.

Regulation 27 – Verification of Ship Fuel Oil Consumption Data and Operational Carbon Intensity
Sets guidelines for verifying the accuracy of reported fuel oil consumption and operational CII, ensuring data integrity and regulatory compliance.

Regulation 28 – Annual Reporting to the Organization and Record Requirements
Mandates the submission of verified data on fuel oil consumption and CII performance to the IMO and requires ships to keep detailed records for inspection.

This chapter focuses on improving energy efficiency and reducing carbon intensity in both new and existing ships, aligning the maritime sector with global decarbonization goals.

Chapter 5 – Verification of Compliance with the Provisions of This Annex (MARPOL Annex VI)

Regulation 29 – Verification of Compliance
Establishes the framework for verifying that ships comply with the requirements of MARPOL Annex VI. This includes inspections, audits, and reviews of ship documentation, certificates, and operational practices. Authorities are empowered to confirm compliance through port state control measures, flag state surveys, and additional monitoring mechanisms as necessary.

This regulation ensures accountability and enforces adherence to the emission reduction and energy efficiency standards outlined in the annex.

MARPOL Annex VI addresses the monitoring and reporting of energy efficiency for ships of 5,000 gross tonnage and above. This regulation aims to enhance transparency and promote data-driven decision-making in the shipping industry, ultimately leading to more energy-efficient operations and reduced GHG emissions. Under this regulation, ships are required to collect and report data on their fuel consumption, distance traveled, and hours underway, as well as other relevant information that enables the calculation of the ship’s energy efficiency. This data is used to determine the ship’s annual average carbon intensity indicator (CII), which is then reported to the ship’s flag state and the International Maritime Organization (IMO). The flag state verifies the data and issues a Statement of Compliance (SOC) to confirm that the ship has met its monitoring and reporting obligations. The collected data is also used to develop a global database on ship energy efficiency, which informs policy-making and helps track the industry’s progress towards meeting its GHG emissions reduction targets. By implementing onboard monitoring and reporting requirements, Regulation 12 of MARPOL Annex VI helps to ensure that the shipping industry is held accountable for its energy efficiency and environmental performance.

MULTIPLE CHOICE QUESTIONS – MARPOL ANNEX VI (Air Pollution Prevention)

What is the main focus of MARPOL Annex VI?
A. Prevention of oil pollution
B. Prevention of garbage discharge
C. Prevention of air pollution from ships
D. Prevention of ballast water contamination

Correct Answer: C. Prevention of air pollution from ships

Which of the following emissions is not directly regulated under MARPOL Annex VI?
A. Sulphur oxides (SOx)
B. Carbon monoxide (CO)
C. Nitrogen oxides (NOx)
D. Volatile Organic Compounds (VOCs)

Correct Answer: B. Carbon monoxide (CO)

What is the global sulphur limit for marine fuel as per Regulation 14 of Annex VI (as of 2020)?
A. 1.5% m/m
B. 1.0% m/m
C. 0.50% m/m
D. 0.10% m/m

Correct Answer: C. 0.50% m/m

In Emission Control Areas (ECAs), what is the maximum permitted sulphur content in fuel oil?
A. 1.0%
B. 0.5%
C. 0.1%
D. 0.05%

Correct Answer: C. 0.1%

Which certificate is issued under MARPOL Annex VI upon successful survey and compliance?
A. International Sewage Pollution Certificate (ISPC)
B. International Garbage Management Certificate
C. International Air Pollution Prevention (IAPP) Certificate
D. Ship Energy Audit Certificate

Correct Answer: C. International Air Pollution Prevention (IAPP) Certificate

What is the purpose of the EEDI (Energy Efficiency Design Index)?
A. To measure crew performance
B. To calculate ship maintenance schedules
C. To assess the energy efficiency of new ship designs
D. To monitor incinerator emissions

Correct Answer: C. To assess the energy efficiency of new ship designs

What is the function of the Ship Energy Efficiency Management Plan (SEEMP)?
A. To plan dry-dock schedules
B. To reduce noise emissions
C. To guide operational energy efficiency improvements
D. To handle oil spills

Correct Answer: C. To guide operational energy efficiency improvements

Which new Emission Control Area (ECA) becomes effective for SOx on 1 May 2025?
A. South Pacific
B. Mediterranean Sea
C. Gulf of Aden
D. Great Barrier Reef

Correct Answer: B. Mediterranean Sea

What must the Bunker Delivery Note (BDN) include as of May 2024?
A. CO₂ emission rating
B. Port of departure
C. Flashpoint of the fuel oil or a compliance statement
D. Ship’s ballast tank data

Correct Answer: C. Flashpoint of the fuel oil or a compliance statement

What rating system is used under the Carbon Intensity Indicator (CII) framework?
A. A to F
B. 1 to 10
C. A to E
D. Low, Medium, High

Correct Answer: C. A to E

TRUE/FALSE QUESTIONS – MARPOL ANNEX VI (Air Pollution and Energy Efficiency)

MARPOL Annex VI regulates both NOx and SOx emissions from ships.
True

The EEDI applies only to existing ships.
False
Explanation: The EEDI applies to new ships; EEXI applies to existing ships.

VOC controls under Annex VI are mandatory for all types of vessels.
False
Explanation: VOC controls specifically target tankers handling crude oil.

Shipboard incineration of polychlorinated biphenyls (PCBs) is prohibited under Annex VI.
True

Regulation 22A requires ships to report fuel oil consumption data to the IMO.
True

The use of alternative emission-reduction technologies is not permitted under Annex VI.
False
Explanation: Regulation 4 allows for approved equivalents like scrubbers.

Ships operating in ECAs must comply with stricter NOx and SOx limits.
True

Fuel suppliers are required to follow ISO 8217 standards under Regulation 18.
True

The Mediterranean Sea is classified as a Sulphur Emission Control Area starting in 2023.
False
Explanation: The Mediterranean Sea becomes an SOx ECA on 1 May 2025.

The Operational Carbon Intensity Indicator (CII) measures CO₂ per ton-mile and contributes to a ship’s annual carbon rating.
True

By:Dr.R.Karimpour

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