MARPOL — Marine Pollution Prevention
International Convention for the Prevention of Pollution from Ships 1973, as modified by the 1978 Protocol (MARPOL 73/78), and as amended. Six annexes covering all sources of ship-generated pollution from oil to GHG emissions.
Oil Pollution Prevention
Regulations for the prevention of pollution by oil — discharge of oil, equipment requirements (oily water separator, ORB), oil record book, and IOPP Certificate.
Noxious Liquid Substances (NLS)
Control of pollution by noxious liquid substances carried in bulk — categories X, Y, Z and OS. Stripper system requirements, prewash procedures, tank certificates.
Harmful Substances in Packaged Form
Prevention of pollution by harmful substances carried in packaged form — applies to IMDG Code substances identified as marine pollutants.
Sewage Pollution Prevention
Prevention of pollution from sewage — holding tanks, comminuting and disinfecting systems, treatment plants, and discharge limitations.
Garbage Management
Prevention of pollution from garbage — discharge prohibition of all garbage outside special areas, garbage management plan, garbage record book.
Prevention of Air Pollution from Ships
SOx, NOx, VOCs, ODS, PM emissions control. Fuel oil quality requirements (0.5% global sulphur cap, 0.1% in ECAs). CII, EEXI, EEDI ratings. 2023 GHG Strategy.
2023 IMO GHG Strategy (MEPC.377(80))
The revised 2023 IMO GHG Strategy commits to net-zero GHG emissions from international shipping by or around 2050. Key milestones under MARPOL Annex VI:
CII Rating reviews — enhanced technical/operational measures
GHG Fuel standard (mid-term measure) — MEPC 82 decisions
20–30% GHG reduction vs 2008 baseline
70–80% GHG reduction vs 2008 baseline
Net-zero GHG emissions from international shipping
EEDI, EEXI, CII and energy efficiency plan (SEEMP Part III)
Frequently Asked Questions
What is MARPOL 73/78?
MARPOL 73/78 is the International Convention for the Prevention of Pollution from Ships, combining the original 1973 convention with the 1978 Protocol. It has six annexes covering oil (Annex I), noxious liquid substances (II), packaged harmful substances (III), sewage (IV), garbage (V), and air pollution including sulphur, NOx and GHG emissions (Annex VI).
What is the global sulphur cap under MARPOL Annex VI?
Since 1 January 2020, MARPOL Annex VI Regulation 14 requires ships to use fuel oil with a sulphur content of no more than 0.50% m/m globally (down from 3.5%). In Emission Control Areas (ECAs) including the North Sea, Baltic Sea and North American waters, the limit is 0.10% m/m. Ships may also use approved exhaust gas cleaning systems (scrubbers) as an equivalent.
What is CII under MARPOL Annex VI?
The Carbon Intensity Indicator (CII) is a mandatory measure under MARPOL Annex VI Regulation 28 (in force from January 2023) that rates ships A–E based on their operational carbon intensity. Ships rated D for three consecutive years or E for one year must develop corrective action plans in their SEEMP Part III. CII is calculated annually as CO₂ emissions per transport work.
What is an Emission Control Area (ECA)?
An Emission Control Area (ECA) is a sea area where stricter controls apply to reduce SOx, NOx, and PM emissions from ships. Designated ECAs include the Baltic Sea, North Sea, North American ECA, and US Caribbean ECA. In ECAs, the sulphur limit is 0.10% m/m and NOx Tier III limits apply to new engines.
About This Page
Information compiled by the HeyMariner maritime intelligence team with expertise in IMO regulations, NAVAREA coordination, and maritime safety. Data sourced from official IMO publications, NGA MSI, and flag state administrations. Last reviewed: 2026.