International shipping is regulated by the International Maritime Organization (IMO), a United Nations body. The scope of the regulations includes prevention of air pollution.
The most commonly used marine fuels are petroleum based and may contain varying levels of sulphur depending on the specific fuel type and the crude mix from which the fuel has been derived. Heavy Fuel Oil (HFO) is the most widely used marine fuel. The average sulphur level in HFO over the past 3 years (2015 -2017) amounted to 2.54%, as reported by IMO’s sulphur monitoring program.
When the fuel is used, the sulphur contained in the fuel will give rise to sulphur oxides in the exhaust emissions of the ship. Sulphur oxides contribute to the formation of acid rain as well as the formation of secondary aerosol particles that are of concern from a health perspective. Therefore SOx emissions are regulated by IMO with a stepwise reduction being implemented since 2008. Emission Control Areas for SOx and PM (SOx ECAs) have been established in the most sensitive areas (Baltic Sea, North Sea and Channel, USA and Canadian coastal zones). In these ECAs, maximum sulphur levels have been reduced from 1.5% initially, to 1% in 2010 and 0.10% in 2015. Outside of these areas, the maximum sulphur level has been reduced from 4.5% initially to 3.50% in 2012, and will now be reduced further to 0.50% as of January 2020, as decided in October 2016.
Appropriate fuel parameters required to ensure safe and smooth operation on board vessels have been defined in a standard from the International Organization for Standardization (ISO). The latest version of ISO’s marine fuel standard is referenced as ISO 8217:2017
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