# MARPOL Annex VI | Navatom Maritime Glossary
MARPOL Annex VI is the part of the MARPOL convention that limits air pollution from ships. It was adopted in 1997 and has been in force since 2005. It limits sulphur oxide, nitrogen oxide and ozone-depleting emissions. Its energy efficiency rules include the EEXI, the CII and the SEEMP.

URL: https://navatom.com/glossary/marpol-annex-vi

## Synonyms
- MARPOL Annex 6
- Air Pollution Regulations

## Definition
## What Is MARPOL Annex VI?
MARPOL Annex VI is the annex to the International Convention for the Prevention of Pollution from Ships that specifically addresses the prevention of air pollution from ships. Adopted in 1997 and entering into force in 2005, Annex VI sets limits on the emissions of sulphur oxides (SOx), nitrogen oxides (NOx), particulate matter (PM), and ozone-depleting substances (ODS) from ship exhausts.
It also establishes requirements for shipboard incineration and the quality of fuel oil used on board. Over the past decade, Annex VI has become the primary regulatory vehicle for the IMO's greenhouse gas reduction strategy, incorporating requirements for energy efficiency and carbon intensity that affect every commercial vessel.
## Emission Control Areas and the 2020 Sulphur Cap
Annex VI designates specific Emission Control Areas (ECAs) where stricter emission limits apply. Currently, ECAs include the Baltic Sea, the North Sea, the North American coastline, and the United States Caribbean Sea.
Within ECAs, the sulphur content of fuel must not exceed 0.10 percent. Outside ECAs, the global sulphur cap was reduced to 0.50 percent effective January 1, 2020, a landmark regulation known as IMO 2020.
Ships can comply by using compliant low-sulphur fuel, installing exhaust gas cleaning systems (scrubbers), or using alternative fuels such as LNG. For NOx, Annex VI establishes three tiers of increasingly stringent limits based on engine construction date, with Tier III engines required in NOx ECAs.
## EEXI and CII — The Decarbonization Amendments
Amendments to Annex VI that took effect in January 2023 introduced two major greenhouse gas measures. The Energy Efficiency Existing Ship Index (EEXI) is a one-time technical measure requiring existing ships to meet a minimum energy efficiency standard based on their design.
The Carbon Intensity Indicator (CII) is an annual operational measure that rates each ship's carbon intensity on a scale from A to E, with ships rated D or E for consecutive years required to submit corrective action plans. These measures represent the IMO's short-term strategy for reducing GHG emissions from international shipping and have placed carbon performance tracking at the center of ship management.
## How Software Supports Annex VI Compliance
Managing compliance with MARPOL Annex VI requires continuous monitoring of fuel consumption, emissions data, and energy efficiency metrics across the fleet. Ship management software automates fuel oil data collection from noon reports, calculates running CII ratings, tracks bunker delivery notes for sulphur content verification, and generates the reports required for IMO Data Collection System (DCS) submissions.
Voyage optimization tools help operators plan routes and speeds that improve CII ratings, while certificate management modules ensure that EIAPP certificates, IAPP certificates, and SEEMP Part III documentation are always current. By integrating these functions, software transforms Annex VI compliance from a fragmented manual process into a streamlined, data-driven operation.

## Related Terms
- [MARPOL](https://navatom.com/glossary/marpol) — MARPOL is the International Convention for the Prevention of Pollution from Ships. It is the main international convention on preventing pollution of the sea by ships, from operational or accidental causes. It was adopted in 1973 and modified by the 1978 Protocol. Its six annexes cover oil, chemicals, harmful packaged substances, sewage, garbage and air emissions.
- [SEEMP](https://navatom.com/glossary/seemp) — The Ship Energy Efficiency Management Plan (SEEMP) is a mandatory operational plan under MARPOL Annex VI. Shipping companies use it to manage and improve the energy efficiency of their vessels over their whole working life.
- [CII Rating](https://navatom.com/glossary/cii-rating) — The Carbon Intensity Indicator (CII) is an IMO operational measure of how efficiently a ship carries cargo for the CO2 it emits. Each ship gets a rating from A to E, on a scale that tightens every year.