The revision of MARPOL Annex VI and the NOx Technical Code (Annex VI) is on track for formal adoption in October 2008 and is likely to enter into force in March 2010.

A unanimous proposal, hammered out by an International Maritime Organization (IMO) working group which met in London April 1-3, passed with flying colours on the final day of the 57th session of the IMO's Marine Environment Protection Committee (MEPC 57).

Bryan Wood-Thomas, who chaired the working group on Annex VI, stressed that the proposal was unanimous and contained no insertions or square brackets, a sign of the broad consensus behind the final document to MEPC 57.

But he warned that the agreement was vulnerable and could unravel if subject to fresh opposition at Friday's plenary meeting.

Wood-Thomas reflected the general feelings when he said the working group's arrival at a consensus proposal was 'remarkable'.

Indeed it came as quite a surprise to many after an unpromising start to the week, with the MEPC appearing deeply split during Monday's opening plenary, in particular with respect to future sulphur limits in marine fuels.

Despite that, the working group agreed this week to a series of ambitious reductions of fuel sulphur content in the coming years that it said would result in significant reduction of SOx (sulphur oxides) and PM (particulate matter) emissions from ships.

The far-reaching measures include progressively lower sulphur limits in what are now referred to as emission control areas (ECAs).

In ECAs, sulphur limits are set to drop to 1.00% in March 2010 and to 0.10% in January 2015.

The global sulphur cap will be reduced to 3.50% in January 2012, with a long-term global target of just 0.50% in 2020, subject to a review in 2018.  If the 2018 review 'fails', the 0.50% sulphur cap may be deferred until the start of 2025.

The working group also agreed that exhaust gas cleaning systems (EGCS) and other alternative technologies   or fuels to achieve the relevant emission reductions would be allowed in Annex VI.

Moreover, the working group's paper to MEPC 57 included draft revised guidelines for EGCS and interim washwater criteria for such systems, crucial elements in facilitating the use of scrubbers as an alternative to low-sulphur fuels.

Wood-Thomas noted concerns about availability of fuel, hence the 2018 review.

The working group report included a statement from the International Petroleum Industry Environmental Conservation Association (IPIECA) cautioning that the oil industry did not expect there would be sufficient availability of shipping fuel at 0.10% and 0.50% sulphur in all regions by the desired dates.

Summarising the revised sulphur standards, Wood-Thomas said they represented "a dramatic step forward" and proved that the IMO has the political will and ability to deliver a meaningful response to air quality issues.

Other key elements achieved this week included an agreement not to pursue an IMO fuel quality standard, but instead forward a list of relevant quality parameters to the International Standards Organization (ISO) with a view to revise the ISO 8217 fuel standard in line with the needs of Annex VI.

It was also agreed that the IMO Secretariat should send out a circular with Unified Interpretations relating to the verification of sulphur content in fuel oil.

There was a palpable sense of relief as the working group's proposal sailed through at Friday's plenary, meaning the revised Annex VI now goes forward to MEPC 58 in October with a view to formal adoption.

A round of applause broke out as it looked like what has been a long and arduous debate was finally reaching its conclusion.

With clear goals in place, the global shipping, refining, marine fuels and related industries can begin to plan for the future.