Emission Control Areas (ECAs)

CANADIAN ARCTIC ECA (MEPC 82)

Adopted by IMO Resolution MEPC.392(82), the Canadian Arctic ECA entered into force on March 1, 2026.

Figure 2: Canadian Arctic ECA 

For sulfur oxides (SOₓ) and particulate matter (PM), ships operating in the area will be required to use fuel oil with a sulfur content not exceeding 0.10% by mass.  This requirement will be fully enforced starting March 1, 2027, following the one-year grace period on enforcement, set to ensure a smooth transition.

Regarding nitrogen oxides (NOₓ), the marine diesel engines with a power output of more than 130 kW installed on ships operating in the area, must be certified to the IMO Tier III emission standard. This requirement applies to ships constructed (keel laying date) on or after January 1, 2025.

NORWEGIAN SEA ECA (MEPC 82)

Adopted by IMO Resolution MEPC.392(82), the Canadian Arctic ECA entered into force on March 1, 2026.

Figure 3. Norwegian Sea ECA

For sulfur oxides (SOₓ) and particulate matter (PM), ships operating in the area will be required to use fuel oil with a sulfur content not exceeding 0.10% by mass.  This requirement will be fully enforced starting March 1, 2027, following the one-year grace period on enforcement, set to ensure a smooth transition.

Regarding nitrogen oxides (NOₓ), the marine diesel engines with a power output of more than 130 kW installed on ships operating in these areas, must be certified to the IMO Tier III emission standard. This requirement applies to:

1.    Ships for which the building contract is placed on or after March 1, 2026.

2.    In the absence of a building contract, the keels of which are laid, or which are at a similar stage of construction on or after September 1, 2026; or

3.    The delivery of which is on or after March 1, 2030.

NORTH-EAST ATLANTIC OCEAN ECA (MEPC 84)

Adopted by IMO Resolution MEPC.407(84), the North-East Atlantic Ocean ECA will enter into force on September 1, 2027.

For sulfur oxides (SOₓ) and particulate matter (PM), ships operating in the area will be required to use fuel oil with a sulfur content not exceeding 0.10% by mass.  This requirement will be fully enforced starting September 1, 2028, following a one-year grace period, in line with regulation 14.6 of MARPOL Annex VI.

Regarding nitrogen oxides (NOₓ), the marine diesel engines with a power output of more than 130 kW installed on ships operating in these areas, must comply with IMO Tier III emission limit. This requirement applies to:

1.           Ships for which the building contract is placed on or after January 1, 2027.

2.           In the absence of a building contract, the keels of which are laid, or which are at a similar stage of construction on or after July 1, 2027; or

3.           The delivery of which is on or after January 1, 2031.

Figure 4. North-East Atlantic Ocean

The Mediterranean Sea SOₓ ECA (MEPC 79)

Mediterranean Sea Emission Control Area for Sulphur Oxides (SOₓ) and Particulate Matter (PM) entered into effect on May 1, 2025, introducing the requirement for ships operating in the area to use fuel oils with a sulfur content not exceeding 0.10% by mass.

Resolution MEPC.361(79) was brought before the IMO in December 2021 and adopted December 16, 2022. The following changes to MARPOL Annex VI took place in accordance to the conclusions of the MEPC 79th session:

1. Designation of the Mediterranean Sea as an ECA entered into force on May 1, 2024, with a one-year grace period on implementation, set to ensure a smooth transition
2. SOx limit of 0.1% m/m to be fully enforced starting May 1, 2025.

Other ECAs (Regulations 13.6 and 14.3 of MARPOL Annex VI)

The North American area, the Caribbean Sea, the Baltic Sea area and the North Sea area are currently designated as both NO_x and SOₓ ECAs.

1.     North American area: It covers the area of the Pacific and Atlantic coasts of Canada and the United States, including the French territory of Saint-Pierre-et-Miquelon, as well as the Gulf of Mexico coast.               

• NO_x Emissions: Ships constructed (keel laying date) on or after January 1, 2016, operating in this area are to comply with IMO Tier III emission limit, except engines solely used for emergency applications such as engines for emergency generators, emergency fire pumps and engines installed in lifeboats.
• SO_x and PM Emissions: From August 1, 2012, the sulphur content of fuel oil used on board the ship shall not exceed 0.10% m/m.

2.     Caribbean Sea: It applies within designated waters around Puerto Rico and the U.S. Virgin Islands. 

• NO_x Emissions: Ships constructed (keel laying date) on or after January 1, 2016, operating in this area are to comply with IMO Tier III emission limit, except engines solely used for emergency application such as engines for emergency generators, emergency fire pumps and engines installed in lifeboats
• SO_x and PM Emissions: From January 1, 2014, the sulphur content of fuel oil used on board the ship shall not exceed 0.10% m/m.

3.     Baltic Sea area: It covers the Baltic Sea, including the Gulf of Bothnia, the Gulf of Finland, and the entrance to the Baltic Sea bounded by the Skaw (57°44.8′ N) in the Skagerrak. 

• NO_x Emissions: Ships constructed (keel laying date) on or after January 1, 2021, operating in this area must comply with Tier III NOₓ emission limits, except engines solely used for emergency application such as engines for emergency generators, emergency fire pumps and engines installed in lifeboats.
• SO_x Emissions: From May 19, 2006, the sulphur content of fuel oil used on board the ship shall not exceed 0.10% m/m.

4.     North Sea area: It covers the North Sea, including Skagerrak, and the English Channel and its approaches.

• NO_x Emissions: Ships constructed (keel laying date) on or after January 1, 2021, operating in this area must comply with Tier III NOₓ emission limits, except engines solely used for emergency application such as engines for emergency generators, emergency fire pumps and engines installed in lifeboats.
• SO_x Emissions: From November 22, 2007, the sulphur content of fuel oil used on board the ship shall not exceed 0.10% m/m.

ACTIONS FOR COMPLIANCE

The following actions are recommended to help ensure timely compliance with the newly approved ECAs:

1. Fuel Compliance and Changeover Procedures: Shipowners should assess their fuel options and switch to low-sulfur fuels compliant with the 0.1% m/m sulfur content requirement.  Ships that utilize separate fuel oils with sulfur contents above 0.1% m/m must allow adequate time for their fuel oil service systems to be completely flushed of non-compliant fuels prior to entering the SO_x ECAs. Vessels must log details of their low-sulfur fuel oils, including tank volumes, as well as the date, time and position where any fuel changeover operation is finished.
2. Exhaust gas cleaning systems: For ships opting to continue using higher sulfur content fuel, the installation of exhaust gas cleaning systems can help reduce sulfur emissions. Shipowners should evaluate the feasibility, cost, and operational implications of installing scrubbers on their vessels.
3. NO_x Reduction Technologies: Shipowners should evaluate the most suitable NOₓ reduction technology based on their vessel’s engine type and operational needs. Common options include Selective Catalytic Reduction (SCR), Exhaust Gas Recirculation (EGR), and dual-fuel engines. 
4. Alternative Fuels: Exploring the use of alternative fuels, such as liquefied natural gas (LNG), biofuels or hydrogen, can significantly reduce emissions within the ECA. Ship owners should assess the availability, infrastructure, and compatibility of these fuels with their vessels' engines to ensure a smooth transition. 
5. Engine Compliance and Certification: Shipowners should ensure that all marine diesel engines over 130 kW comply with IMO Tier III NOₓ emission standards, particularly for vessels constructed or delivered within the applicable regulatory dates. For newbuilds, engine certification under the NOₓ Technical Code 2008 must be integrated into the design process. Additionally, verify that the Engine International Air Pollution Prevention (EIAPP) Certificate, the International Air Pollution Prevention (IAPP) Certificate, and the NOₓ Technical File are up to date and reflect compliance with Tier III standards. 
6. Logbook and Recordkeeping Requirements: Maintain a logbook to record the tier status of the engines at entry into or exit, from an ECA, or when the on/off status changes within such area, together with the date, time and position of the ship in accordance with Regulation 13/5.3 of MARPOL Annex VI.
7. Crew Training and Awareness: Shipowners should invest in crew training programs to enhance awareness of the new emission requirements, fuel handling procedures and emission control technologies.

Frequently Asked Questions

1.   Can a ship use its incinerator to burn oil sludge within an Emission Control Area (ECA)?

Yes, a ship can use its IMO type-approved incinerator, operated according to its operating manual and temperature requirements, to burn oil sludge generated from the fuel oil treatment system within an ECA.

According to IMO Resolution MEPC.244(66), this applies even if the sludge originates from fuel oil with a sulfur content higher than 0.1%, because the emissions generated from burning sludge in the incinerator represent only a small fraction of the total emissions from the ship.

2.    Are there any regional restrictions on the use of incinerators to burn waste oil sludge?

Yes, although MARPOL Annex VI allows sludge incineration in ECAs regardless of the sulfur content of the fuel oil from which it was generated, regional restrictions may apply. Examples include:

• Helsinki Convention: Prohibits incineration of ship-generated waste in the territorial waters of Baltic Sea countries.
• California regulations: Prohibit onboard incineration within 3 nautical miles of its coast.
• Certain ports or coastal states: May require prior permission or prohibit incineration altogether within their jurisdiction.

3.    Since MARPOL Tier III NOx requirements have applied to ships constructed on or after 1 January 2016, why do the new ECAs apply NOx requirements to vessels built after a later construction date?

MARPOL Annex VI Tier III NOₓ requirements have applied to ships constructed (keel laid) on or after 1 January 2016 when operating in the existing NOₓ ECAs (North American and US Caribbean).

Subsequently, the Baltic Sea and North Sea ECAs entered into force for ships constructed (keel laid) on or after 1 January 2021. Therefore, a ship with a keel laying date between 1 January 2016 and 1 January 2021 must comply with Tier III requirements when operating in the North American and US Caribbean ECAs, but not when operating in the Baltic Sea or North Sea.

For the newly designated ECAs, Norwegian Sea (effective 1 March 2026) and North-East Atlantic Ocean (effective 1 September 2027), IMO has adopted specific application dates for Tier III compliance based on the ship’s construction or contract date. This approach is intended to avoid retroactive application to vessels already built before the ECA designation was finalized.

4.    If a ship with a contract signed on 1 April 2026 and keel laying date 1 August 2026 (subject to NOx Tier III requirements for the Norwegian ECA based on the contract date) undergoes major engine conversion, in 2032, would the engine be required only to meet the NOx Tier II standard according to regulation 2.1.28 “ship constructed” term, which is based  solely on the keel-laying date?

MEPC 84 approved a new Unified Interpretation (UI) of regulation 13.2.3 of MARPOL Annex VI (major conversion of engines), that clarifies that for ships constructed on or after the relevant dates and operating in the Norwegian Sea or North-East Atlantic NOx Emission Control Areas undergoing major conversion, the three dates application criteria based on the building contract date, or in absence of a building contract the keel laying date, or the delivery date should be used to determine "the time the ship was constructed", without prejudice to the definition of "ship constructed" as set out in regulation 2.1.28.

Therefore, in this scenario, although the keel‑laying date (1 August 2026) is before 1 September 2026, the major engine conversion (in 2032) must comply with NOx Tier III requirements, according to the application of the three‑date criteria system (the contract was signed on 1 April 2026).