Prevention of Air Pollution from Ships

Regulations for the Prevention of Air Pollution from Ships were adopted in the 1997 Protocol to MARPOL 73/78 and are 

included in Annex VI of the Convention.

Revised Anned VI adopted October 2008: MEPC.176(58) Amendments to the Annex of the Protocol of 1997 to amend the International 

Convention for the Prevention of Pollution from Ships, 1973, as modified by the Protocol of 1978 relating thereto (Revised MARPOL Annex 

VI) 

Marine Environment Protection Committee (MEPC) - 58th session: 6 to 10 October 2008 

The Marine Environment Protection Committee (MEPC) of the International Maritime Organization (IMO) unanimously 

adopted amendments to the MARPOL Annex VI regulations to reduce harmful emissions from ships even further, when it 

met for its 58th session at IMO's London headquarters.

The main changes to MARPOL Annex VI will see a progressive reduction in sulphur oxide (SOx) emissions from ships, with 

the global sulphur cap reduced initially to 3.50% (from the current 4.50%), effective from 1 January 2012; then 

progressively to 0.50 %, effective from 1 January 2020, subject to a feasibility review to be completed no later than 2018.

The limits applicable in Sulphur Emission Control Areas (SECAs) will be reduced to 1.00%, beginning on 1 July 2010 (from 

the current 1.50 %); being further reduced to 0.10 %, effective from 1 January 2015.

Progressive reductions in nitrogen oxide (NOx) emissions from marine engines were also agreed, with the most stringent 

controls on so-called "Tier III" engines, i.e. those installed on ships constructed on or after 1 January 2016, operating in 

Emission Control Areas.

The revised Annex VI will allow for an Emission Control Area to be designated for SOx and particulate matter, or NOx, or 

all three types of emissions from ships, subject to a proposal from a Party or Parties to the Annex, which would be 

considered for adoption by the Organization, if supported by a demonstrated need to prevent, reduce and control one or all 

three of those emissions from ships. 

The revised Annex VI will enter into force on 1 July 2010, under the tacit acceptance amendment procedure.

MARPOL Annex VI Regulations for the Prevention of Air Pollution from Ships entered into force in May 2005 and has, so far, 

been ratified by 53 countries, representing approximately 81.88 % of the gross tonnage of the world's merchant shipping 

fleet. 

The MEPC also adopted amendments to the associated NOx Technical Code, to give a revised NOx Technical Code 2008. 

The amended Code includes a new chapter based on the agreed approach for NOx regulation of existing (pre-2000) 

engines established in MARPOL Annex VI, and provisions for direct measurement and monitoring methods, a certification 

procedure for existing engines, and test cycles to be applied to Tier II and Tier III engines. 

Revised Guidelines for Exhaust Gas Cleaning Systems and Guidelines for the development of a VOC management plan 

were also adopted. 

Speaking following the adoption of the MARPOL Annex VI amendments, IMO Secretary-General Efthimios Mitropoulos 

hailed the landmark achievement as "a monumental decision in IMO's history, a decision that proves, once again, that the 

Organization is focused, united and relevant as the international body capable of dealing with all items on its agenda, an 

organization that sets global standards in a global environment". 

The revised measures are expected to have a significant beneficial impact on the atmospheric environment and on human 

health, particularly that of people living in port cities and coastal communities. 

Tacit amendment procedure: The amendments enter into force six months after the deemed acceptance date, 1 

January 2010, unless within the acceptance period an objection is communicated to the Organization by not less than one 

third of the Parties or by the Parties the combined merchant fleets of which constitute not less than 50 per cent of the 

gross tonnage of the world's merchant fleet. 

Background: 
The Protocol of 1997 (MARPOL Annex VI)

July 2005 amendments

Review of Annex VI

Greenhouse gases

Background on air pollution and development of the MARPOL regulations

Information resources on prevention of air pollution from ships

The Protocol of 1997 (MARPOL Annex VI)

The Protocol adopted in 1997 included the new Annex VI of MARPOL 73/78, which 

entered into force on 19 May 2005.

MARPOL Annex VI sets limits on sulphur oxide and nitrogen oxide emissions from 

ship exhausts and prohibits deliberate emissions of ozone depleting substances. The 

annex includes a global cap of 4.5% m/m on the sulphur content of fuel oil and calls 

on IMO to monitor the worldwide average sulphur content of fuel. 

Annex VI contains provisions allowing for special SOx Emission Control Areas 

(SECAS) to be established with more stringent controls on sulphur emissions. In 

these areas, the sulphur content of fuel oil used onboard ships must not exceed 

1.5% m/m. Alternatively, ships must fit an exhaust gas cleaning system or use any 

other technological method to limit SOx emissions. The Baltic Sea Area is designated 

as a SOx Emission Control area in the Protocol. 

The North Sea was adopted as SOx Emission Control Area in July 2005. 

Annex VI prohibits deliberate emissions of ozone depleting substances, which include halons and chlorofluorocarbons 

(CFCs). New installations containing ozone-depleting substances are prohibited on all ships. But new installations 

containing hydro-chlorofluorocarbons (HCFCs) are permitted until 1 January 2020. 

Annex VI also sets limits on emissions of nitrogen oxides (NOx) from diesel engines. A mandatory NOx Technical Code, 

which defines how this shall be done, was adopted by the Conference under the cover of Resolution 2.

The Annex also prohibits the incineration onboard ship of certain products, such as contaminated packaging materials and 

polychlorinated biphenyls (PCBs).

July 2005 amendments

The Marine Environment Protection Committee (MEPC) at its 53rd session in July 2005 adopted amendments to MARPOL 

Annex VI, including one on the new North Sea SOx Emission Control Area (SECA). The entry into force date for the North 

Sea SECA amendment is expected to be 22 November 2006, with its full implementation 12 months later. 

The Committee noted information gained from monitoring the worldwide sulphur content in fuel oils for 2004 which gave a 

three-year (2002-2004) rolling average of sulphur content in fuel oil worldwide of 2.67% m/m.

The MEPC adopted Guidelines on on-board exhaust gas-SOx cleaning systems; Survey Guidelines under the Harmonized 

System for Survey and Certification for MARPOL Annex VI; Unified interpretations of MARPOL Annex VI; and Guidelines for 

Port State Control under MARPOL Annex VI. 

The MEPC also adopted amendments to update the NOx Technical Code. 

The MEPC approved Interim Guidelines for Voluntary Ship CO2 Emission Indexing for Use in Trials.

Review of Annex VI

Revised Anned VI adopted October 2008: MEPC.176(58) Amendments to the Annex of the Protocol of 1997 to amend the International 

Convention for the Prevention of Pollution from Ships, 1973, as modified by the Protocol of 1978 relating thereto (Revised MARPOL Annex 

VI) 
At its 53rd session in July 2005, the MEPC agreed on the need to undertake a review of Annex VI and the NOx Technical 

Code with a view to revising the regulations to take account of current technology and the need to further reduce 

emissions from ships. MEPC instructed the Sub-Committee on Bulk Liquids and Gases (BLG) to carry out the review by 

2007, and specifically to:

- examine available and developing techniques for the reduction of emissions of air pollutants; review the relevant 

technologies and the potential for a reduction of NOx emissions and recommend future limits for NOx emissions;

- review technology and the need for a reduction of SOx emissions and justify and recommend future limits for SOx 

emissions;

- consider the need, justification and possibility of controlling volatile organic compounds emissions from cargoes;

- with a view to controlling emissions of particulate matter (PM), study current emission levels of PM from marine 

engines, including their size distribution and quantity, and recommend actions to be taken for the reduction of PM 

from ships. Since reduction of NOx and SOx emission is expected to also reduce PM emission, estimate the level of 

PM emission reduction through this route;

- consider reducing NOx and PM emission limits for existing engines;

- consider whether Annex VI emission reductions or limitations should be extended to include diesel engines that use 

alternative fuels and engine systems/power plants other than diesel engines; and

- review the texts of Annex VI, NOx Technical Code and related guidelines and recommend necessary amendments.

MEPC 55 outcome

The Marine Environment Protection Committee (MEPC) at its 55th session in October 2006 agreed a work plan, with a 

timetable, to identify and develop the mechanisms needed to achieve the limitation or reduction of carbon dioxide (CO2) 

emissions from ships, noting that climate change caused by greenhouse gas emissions from the burning of fossil fuel is a 

steadily growing concern for most countries. The MEPC noted that shipping, although an environmentally friendly and fuelefficient mode of transport, nevertheless, needs to take action on greenhouse gases (GHG). 

The work plan provides for the further development of the CO2 Emission Indexing Scheme, with Member States and the 

industry asked to continue to carry out trials in accordance with the Interim Guidelines for Voluntary Ship CO2 Emission 

Indexing for Use in Trials (MEPC/Circ.471, issued in 2005); the consideration and evaluation of methodology for CO2

emission baseline(s); and the consideration of technical, operational and market-based methods for dealing with GHG 

emissions. The aim is to complete the work by 2008/2009. 

Following discussions in the Working Group on Air Pollution, the MEPC moved forward with other issues relating to air 

pollution as follows: 

• it agreed eight unified interpretations relating to the implementation and enforcement of MARPOL Annex VI, the 

NOx Technical Code and related guidelines; 

• it approved the standard form of the Sulphur Emissions Control Area (SECA) Compliance Certificate to facilitate 

uniform enforcement and port State control;

• it approved the establishment of a correspondence group to develop washwater discharge criteria for exhaust gas 

SOx cleaning systems;

• regarding standardization of on-shore power supply connections with ships, it agreed that a global standard would 

benefit the shipping industry but agreed to await the finalization of such a standard before taking any decision on 

its possible inclusion in the revised MARPOL Annex VI, noting that the International Organization for 

Standardization (ISO) and the International Electrotechnical Commission (EIC) have established a working group 

on standardization of on-shore power supply for ships at berth; and 

• it agreed that that co-operation between the secretariats of the International Civil Aviation Organization (ICAO) 

and IMO should be strengthened and that developments related to GHG emissions in both Organizations should be 

communicated to each other.

The Sub-Committee on Bulk Liquids and Gases (BLG) is currently undertaking a comprehensive review of MARPOL Annex 

VI and the NOx Technical Code and an intersessional meeting of the BLG Air Pollution Working Group was held from 13 to 

17 November 2006 in Oslo, Norway, to progress the work further.

Sulphur monitoring

The MEPC noted the results of monitoring of the worldwide average of sulphur content of residual fuel oils, which indicated 

that in 2005, almost 90% of the samples had sulphur contents between 1.5 and 4% m/m. Almost 50% was between 2 and 

3% m/m. 219 out of 79,592 (0.3%) of the samples were over 4.5% m/m sulphur, and 5 samples contained more than 5% 

sulphur (compared to 7 samples in 2004). The sulphur content of residual fuel measured for 2003, 2004 and 2005 gave a 

three year rolling average for the period of 2.7%. The rolling average for 2002-2004 was 2.67%. 

MEPC 54 outcome
At its 54th session in March 2006, a working group was established to consider issues relating to the prevention of air 

pollution from ships, including follow-up action to the IMO Policies and practices related to the reduction of greenhouse gas 

emissions from ships (resolution A.963(23)). 

Following the work by the group, the MEPC approved two circulars aimed at assisting implementation of MARPOL Annex VI: 

1. The MEPC Circular on Bunker Delivery Note and Fuel Oil Sampling, to clarify how to comply with regulation 18, which 

places requirements on ship owners and fuel oil suppliers in respect of bunker delivery notes and representative samples of 

the fuel oil received and on Parties to the 1997 Protocol to regulate the bunker suppliers in their ports. The circular urges

all Member States, both Parties and non-Parties to the 1997 Protocol, to require fuel oil suppliers in their ports to comply 

with the requirements and to raise awareness of the necessity to enhance implementation and enforcement of regulation 

18 of Annex VI.

2. The MEPC circular on Notification to the Organization on ports or terminals where volatile organic compounds (VOCs) 

emissions are to be regulated, which notes that regulation 15 of Annex VI requires Parties to inform the Organization of 

their intention to introduce requirements for the use of vapour emission control systems and to notify the Organization of 

ports and terminals under their jurisdiction where such requirements are already in force. However, many terminals are 

implementing or operating such practices without notification to the Organization. The Committee shared the concern that, 

since there is no circulation of such information, it is difficult for owners and operators to prepare for these changes at 

ports and terminals. The circular reiterates that Parties to the 1997 Protocol are required to notify the Organization without 

delay with information on ports and terminals under their jurisdiction at which VOCs emissions are or will be regulated, and 

on requirements imposed on ships calling at these ports and terminals. Any information received by the Organization on 

the availability of vapour emission control systems will be circulated through MEPC circulars so that owners and operators 

will have up to-date information on current and future requirements for the utilization of such systems.

As instructed by MEPC 53, the Sub-Committee on Bulk Liquids and Gases (BLG) will undertake a review of MARPOL Annex 

VI and the NOx Technical Code with a view to revising the regulations to take account of current technology and the need 

to further reduce air pollution from ships. The progress of this work will be reported to the next session of the MEPC.

The Committee and its Working Group on Air Pollution had long and extensive debates on how to follow up resolution 

A.963(23) on IMO Policies and Practices related to the Reduction of Greenhouse Gas Emissions from Ships. By the 

resolution, the Assembly urged MEPC to identify and develop the necessary mechanisms needed to achieve the limitation 

or reduction of GHG emissions from international shipping. Among the items considered was whether only emission of CO2

or of all six greenhouse gases identified by the Kyoto Protocol should be included. The MEPC agreed to consider the followup actions to resolution A.963(23) in a technical and methodological perspective and to concentrate the work on CO2

emissions. The Committee also agreed to continue the work at the next session and, in particular, to consider further a 

draft work plan to identify and develop the mechanisms needed to achieve the goal set by the Assembly.

Greenhouse gases

In November 2003, IMO adopted resolution A.963(23) IMO Policies and practices related to the reduction of 

greenhouse gas emissions from ships. 

At its 52nd session in October 2004, the Marine Environment Protection Committee (MEPC) made progress on developing 

draft Guidelines on the CO2 Indexing Scheme and urged Members to carry out trials using the scheme and to report to the 

next session. One purpose of developing guidelines on CO2emission indexing is to develop a simple system that could be 

used voluntarily by ship operators during a trial period. 

The Committee agreed that a CO2 indexing scheme should be simple and easy to apply and take into consideration matters 

related to construction and operation of the ship, and market based incentives. At its 53rd session in July 2005, the MEPC 

approved Interim Guidelines for Voluntary Ship CO2 Emission Indexing for Use in Trials.

Meanwhile, the Committee recognized that IMO guidelines on greenhouse gas emissions have to address all six 

greenhouse gases covered by the Kyoto Protocol (Carbon dioxide (CO2); Methane (CH4); Nitrous oxide (N2O); 

Hydrofluorocarbons (HFCs); Perfluorocarbons (PFCs); and Sulphur hexafluoride (SF6). 

Background on air pollution 

The issue of controlling air pollution form ships - in particular, noxious gases from ships' exhausts - was discussed in the 

lead up to the adoption of the 1973 MARPOL Convention. However, it was decided not to include regulations concerning air 

pollution at the time.

Meanwhile, air pollution was being discussed in other arenas. The 1972 United Nations Conference on the Human 

Environment in Stockholm marked the start of active international cooperation in combating acidification, or acid rain. 

Between 1972 and 1977, several studies confirmed the hypothesis that air pollutants could travel several thousand 

kilometres before deposition and damage occurred. This damage includes effects on crops and forests.
Most acid rain is caused by airborne deposits of sulphur dioxides and nitrogen oxides. Coal and oil-burning power plants 

are the biggest source of sulphur dioxides while nitrogen oxides come from car, truck - and ship - exhausts.

In 1979, a ministerial meeting on the protection of the environment, in Geneva, resulted in the signing of the Convention 

on Long-range Transboundary Air Pollution by 34 governments and the European Community. This was the first 

international legally binding instrument to deal with problems of air pollution on a broad regional basis.

Protocols to this Convention were later signed on reducing sulphur emissions (1985); controlling emissions of nitrogen 

oxides (1988); controlling emissions of volatile organic compounds (1991) and further reducing sulphur emissions (1994).

During the 1980s, concern over air pollution, such as global warming and the depleting of the ozone layer, continued to 

grow, and in 1987 the Montreal Protocol on substances that Deplete the Ozone Layer was signed.

The Montreal Protocol is an international environmental treaty, drawn up under the auspices of the United Nations, under 

which nations agreed to cut consumption and production of ozone-depleting substances including chlorofluorocarbons 

(CFCs) and halons in order to protect the ozone layer.

A Protocol was adopted in London in 1990 - amending the original protocol and setting the year 2000 as the target 

completion date for phasing out of halons and ozone-depleting CFCs. A second Protocol was adopted in Copenhagen in 

1992, introducing accelerated phase-out dates for controlled substances, cutting short the use of transitional substances 

and the introduction of phase-out dates for HCFCs and methyl bromide(a pesticidal gas which depletes the ozone layer).

CFCs have been in widespread use since the 1950s as refrigerants, aerosol propellants, solvents, foam blowing agents and 

insulants. In shipping, CFCs are used to refrigerate ship and container cargo, insulate cargo holds and containers, air 

condition crew quarters and occupied areas and refrigerate domestic food storage compartments.

Halons, manufactured from CFCs, are effective fire extinguishers used in portable fire extinguishers and fixed fire 

prevention systems. 

IMO begins work on air pollution

At IMO, the Marine Environment Protection Committee (MEPC) in the mid-1980s had been reviewing the quality of fuel oils 

in relation to discharge requirements in Annex I and the issue of air pollution had been discussed. 

In 1988, the MEPC agreed to include the issue of air pollution in its work programme following a submission from Norway 

on the scale of the problem. In addition, the Second International Conference on the Protection of the North Sea, held in 

November 1987, had issued a declaration in which the ministers of North Sea states agreed to initiate actions within 

appropriate bodies, such as IMO, "leading to improved quality standards of heavy fuels and to actively support this work 

aimed at reducing marine and atmospheric pollution." 

At the next MEPC session, in March 1989, various countries submitted papers referring to fuel oil quality and atmospheric 

pollution, and it was agreed to look at the prevention of air pollution from ships - as well as fuel oil quality - as part of the 

committee's long-term work programme, starting in March 1990. 

In 1990, Norway submitted a number of papers to the MEPC giving an overview on air pollution from ships. The papers 

noted:

Sulphur emissions from ships' exhausts were estimated at 4.5 to 6.5 million tons per year - about 4 percent of total 

global sulphur emissions. Emissions over open seas are spread out and effects moderate, but on certain routes the 

emissions create environmental problems, including English Channel, South China Sea, Strait of Malacca.

Nitrogen oxide emissions from ships were put at around 5 million tons per year - about 7 percent of total global 

emissions. Nitrogen oxide emissions cause or add to regional problems including acid rain and health problems in local 

areas such as harbours.

Emissions of CFCs from the world shipping fleet was estimated at 3,000-6,000 tons - approximately 1 to 3 percent of 

yearly global emissions. Halon emissions from shipping were put at 300 to 400 tons, or around 10 percent of world 

total. 

Adoption of resolution 
Discussions in the MEPC and drafting work by a working group, led to the adoption in 1991, of an IMO Assembly Resolution 

A.719(17) on Prevention of Air Pollution from Ships.

The Resolution called on the MEPC to prepare a new draft Annex to MARPOL 73/78 on prevention of air pollution.

The new draft Annex was developed over the next six years - and was finally adopted at a Conference in September 1997. 

It was agreed to adopt the new Annex through adding a Protocol to the MARPOL 73/78 Convention, which included the 

new Annex. This enabled specific entry into force conditions to be set out in the protocol.