The International Maritime Organisation (IMO) considers exhaust gas scrubbers to be an acceptable means of reducing vessels’ sulphur emissions and ensuring compliance with MARPOL Annex VI. A separate guideline, Resolution MEPC.259(68), specifies the requirements for the verification, testing, survey and certification of scrubber systems and sets out the criteria for discharging scrubber wash water into the sea.
However, some coastal states and ports have implemented local regulations with more stringent requirements that restrict or completely prohibit the discharge of wash water from open loop scrubbers or prohibit the use of scrubbers.