NOx, SOx, & PM
International standards limiting NOx, SOx, and PM emissions from ships are established through Annex VI of the International Convention for the Prevention of Pollution from Ships, otherwise known as MARPOL. Specific engine design standards, testing protocols, and extensive technical provisions relating to testing and enforcement of these standards are stipulated under MARPOL Annex VI and the NOx Technical Code. SOx and PM emissions are also controlled under MARPOL Annex VI through limitations on the maximum sulphur content allowed in fuels used on board ships or through achievement of equal or superior levels through the use of exhaust gas cleaning systems. Also controlled under MARPOL Annex VI are emissions of ozone depleting substances such as halons and chlorofluorocarbons (CFCs), volatile organic compounds (VOCs), and incineration.
The Annex VI standards were first developed through the International Maritime Organization (IMO) in 1997 and then subject to major revision in October 2008. The October 2008 amendments will result in major reductions of NOx, SOx, and PM emissions around the world with extensive benefits to both human health and the environment.
The World Shipping Council was the first industry organization to explicitly support the adoption of stringent NOx, and SOx standards during negotiations in 2007 and issued a position paper in support of a proposal to revise the MARPOL Annex VI Vessel Air Emissions Treaty to more effectively reduce particulate matter and sulfur and nitrous oxide emissions through a combination of new fuel standards and new engine system standards. Read WSC's position paper.
In April 2008, the WSC issued a statement of support for new standards that were adopted later that year in a set of amendments to MARPOL Annex VI. These new standards form the basis for significant improvements in air emissions from ships to be realized in 2010, 2015, 2020, and later. Read the IMO's news release.
Emission Control Area (ECA)
SOx and PM emissions are controlled under MARPOL Annex VI through global standards applicable to all ships operating around the world and through emission control areas (ECAs) where more stringent limitations are applicable. The maximum sulfur content permitted in marine fuels is currently 4.5% while ships operating in designated emission control areas are subject to a 1.5% limitation. The global limitation falls to 3.5% in 2012 and then to .5% in 2020 pending the results of a review in 2018. Limits in emission control areas fall from 1.5% to 1% in July 2010 and to .1% in 2015. It should be noted that these standards may also be met through the use of exhaust gas cleaning systems often referred to as "scrubbers."
ECAs may be established under the revised Annex to give effect to more stringent standards applicable to SOx and PM, NOx, or all three. ECAs limiting SOx emissions are already established in the Baltic Sea and the North East Atlantic, including the North Sea and waters to the Northwest adjacent to Southern Norway. The IMO agreed in March 2010 to establish a new Emission Control Area addressing NOx, SOx, and PM in waters adjacent to Pacific and Atlantic coast of Canada, the continental United States, Southeastern Alaska, and Hawaii. The applicable controls for the new North American ECA will become effective in August 2012.
Other controls
Other controls applicable to marine traffic in specific geographic areas include fuel quality limitations required by the California Air Resources Board (CARB) for vessels entering California ports and the requirement established by the European Commission for all vessels to use fuel with a maximum sulfur content of 1000 ppm (0.1% sulfur) beginning in January 2010.