MARPOL
The IMO convention preventing pollution from ships — oil, chemicals, sewage, garbage and air emissions across six annexes.
MARPOL — the International Convention for the Prevention of Pollution from Ships — is the principal global treaty on ship-source pollution. Its six annexes cover oil (I), noxious liquids (II), packaged harmful substances (III), sewage (IV), garbage (V) and air pollution (VI).
Annex VI is the one driving the energy-transition rules: it caps sulphur in marine fuel (the 0.50% global limit and tighter ECA limits), restricts NOx, and houses the EEDI, EEXI and CII framework.
On TheMaritime
Also known as: MARPOL, marpol annex vi, marpol convention.
Related terms
International Maritime OrganizationIMO
The United Nations agency that sets global rules for ship safety, security and pollution prevention.
Very Low Sulphur Fuel OilVLSFO
Marine fuel with no more than 0.50% sulphur, the compliant fuel for most waters under the IMO 2020 sulphur cap.
Scrubber
An exhaust gas cleaning system that removes sulphur oxides from a ship’s emissions, letting her burn cheaper high-sulphur fuel.
Carbon Intensity IndicatorCII
An IMO operational measure of how much CO₂ a ship emits per unit of transport work, graded A–E each year.
Energy Efficiency Existing Ship IndexEEXI
A one-time IMO design-efficiency standard that existing ships must meet, the in-service counterpart of the EEDI for new ships.
Plain-English reference definition — our own explanation of a standard shipping concept, not a licensed source or legal advice. See the full glossary or the broader maritime dictionary.
Last reviewed: June 2026.