Published: 3 March 2020


Work by the IMO on the prevention of air pollution from ships led to the adoption of the Protocol of 1997 to the MARPOL Convention.  The Protocol added a new Annex VI to the Convention containing the Regulations for the Prevention of Air Pollution from Ships.  Annex VI provides for a progressive reduction in sulphur oxide (SOx) and nitrogen oxide (NOx) emissions.

Since 1 January 2015, Regulation 14 of Annex VI has required that the sulphur content of fuel oil burned within Emission Control Areas (ECAs) shall not exceed 0.10% m/m. There are currently four ECAs designated under MARPOL, namely the Baltic Sea,  North Sea, North America and US Caribbean Sea areas.

From 1 January 2020, unless local regulations set out stricter standards, all fuel oil burned by ships outside ECAs is required to have a sulphur content not exceeding 0.50% m/m except where the ship is using an approved Exhaust Gas Cleaning System (EGCS, but commonly referred to as a scrubber) installed on board a ship to remove the SOx from the exhaust gases generated by the engines and boilers.

In order to be compliant, Members have had to decide between the  following options:

  • Use of a low sulphur fuel oil with the correct sulphur content;
  • Switching to an alternative source of fuel (e.g. LNG);
  • Installation of a scrubber on board the ship.

There are several different designs of scrubber available, with the system generally falling into one of the following types:

“Open loop” – where sea water is taken on board and used to “scrub” the exhaust gases, which are treated and discharged back to sea, with the natural chemical composition of the sea water used to neutralize the results of SOx removal.

“Closed loop” – where fresh water treated with an alkaline chemical, such as caustic soda, is used to neutralize and scrub the exhaust gases.  The wash water is re-circulated and any losses made up with additional fresh water. A small quantity of the wash water is bled off to a treatment plant before discharge to sea.

“Hybrid” systems – these can operate in either “Open” or “Closed loop” mode and depending on design may operate with either fresh water or sea water when in closed loop mode.

Resolution MEPC.259(68) specifies the IMO’s requirements for the verification, testing, survey and certification of scrubbers systems and sets out the criteria for discharging scrubber wash water into the sea.

More detailed information about scrubbers can be obtained from the Exhaust Gas Cleaning Systems Association’s (EGCSA) website.

A number of countries and port areas currently ban the discharge of wash water from scrubbers, as detailed in the following news item.


All charter parties entered into for delivery after 1 January 2020 should include terms to reflect these regulations.

In order to deal with the regulations BIMCO has published a Marine Sulphur Content Clause

The clause is intended primarily to deal with the new sulphur content regulations and should be used in conjunction with other existing time charter bunker clauses dealing with the specifications, grades and quality of fuel provided by charterers such as those in BIMCO’s Suite of Standard Bunker Clauses for Time Charter Parties.

In addition to the BIMCO clauses, INTERTANKO has issued a Bunker Compliance Clause for Time Charter Parties.  The INTERTANKO  clause is intended to be a stand-alone clause dealing not only with MARPOL Annex VI and other regulatory requirements but also fuel quality issues and industry best practice.

It should be noted that the BIMCO and INTERTANKO clauses are primarily intended to be used by ships that have not installed scrubbers which permit them to use fuel oil with a sulphur content exceeding 0.5% m/m after 1 January 2020.

From 01 March 2020, fuel oil which exceeds the 0.50% sulphur limit cannot be carried in a ship’s fuel oil tanks unless the ship is fitted with an approved exhaust gas cleaning system (EGCS) or equivalent arrangement. For further details please refer to the IMO website.

General advice on issues relating to ship emissions can be found at the following links:

US Environmental Protection Agency (EPA)

United States Coast Guard (USCG)

Frequently asked questions: North American Emission Control Area (ECA) U.S. Coast Guard Office of Commercial Vessel Compliance

US Department of Homeland Security

US Department of Homeland Security, MARPOL Annex VI webpage

European Maritime Safety Agency (EMSA)

EMSA Air Pollution


China MSA Notice-implementation 2020 global sulphur limit

IMO FAQs and guidance

Industry Guidance