The SECA zones (SECA for Sulphur Emission Control Area) are maritime areas in which strict controls of merchant ships have been established by the International Maritime Organization (IMO) to minimize emissions of sulfur oxides (SOx), nitrogen oxides (NOx) and Prohibit any deliberate release of ozone-depleting substances. It also governs waste incineration on board and emissions of volatile organic compounds (VOCs) from tankers.
Adopted in 1997, Annex VI Rules for the Prevention of Air Pollution by Ships of the Marpol Convention establishes:
- emission control areas subject to more stringent controls on SOx emissions;
- NOx emission control areas for Level III NOx emission standards.
This regulation that came into force in 2005 is the contribution of the maritime industry to the overall reduction of greenhouse gas emissions. Annex VI was revised in July 2010 and introduced more stringent emission limits.
Since 2011, four ECAs exist around the world:
- Baltic Sea and North Sea for sulfur emissions;
-North America and United States Caribbean Sea Area for emissions of sulfur and nitrogen oxides and particulates.
Since 1 January 2015, the ECA zones have seen the sulfur content of fuels used on board merchant ships reduced to 0.1% against 1% previously. The limit of 0.1% was previously limited to vessels that spend more than two hours in ports in SECA zones that had to meet these standards during their port stay.