MARPOL Annex VI is the IMO regulation that controls air pollution from ships — sulphur oxides, nitrogen oxides, particulate matter, ozone-depleting substances, VOCs and now GHG. This guide explains the sulphur cap, NOx tiers, EEDI/EEXI/CII, ECAs, and the reporting chain.
MARPOL Annex VI is the sixth annex of the International Convention for the Prevention of Pollution from Ships (MARPOL 73/78). It sets limits on sulphur oxides (SOx) and nitrogen oxides (NOx) emissions, prohibits deliberate emissions of ozone-depleting substances, regulates volatile organic compounds from tankers, and from 2013 introduced energy efficiency and subsequently carbon intensity measures for ships.
From 1 January 2020, the global fuel oil sulphur limit dropped from 3.50% to 0.50% m/m outside Emission Control Areas (ECAs). Inside ECAs, the limit remains 0.10%. Ships comply by (a) using compliant low-sulphur fuel oil (VLSFO/ULSFO), (b) fitting an Exhaust Gas Cleaning System (scrubber) or (c) using an alternative fuel such as LNG, methanol or ammonia.
Designated sea areas with stricter SOx (0.10% sulphur) and, separately, stricter NOx rules:
Ships ≥ 5,000 GT report annual fuel oil consumption to IMO via the flag state — this is the IMO Data Collection System (DCS). DCS data already feeds the CII rating and will feed the emerging IMO Fuel Standard under the IMO Net-Zero Framework.
Run a 3-minute readiness scorecard or book a 30-minute call with our compliance specialists to map this to your fleet.
Take the Readiness Scorecard Contact the Compliance TeamBook a 30-minute call with our maritime compliance specialists. We will review your fleet’s obligations and map a continuous-compliance workflow using the VS Solutions stack (VSIMS, VSMPS, LCA, ESG Portal, CBT, Live Reporting).