Scrubbers have long had a dubious reputation given the water pollution resulting from toxic scrubber discharge on the marine environment. Opportunity Green’s latest legal analysis shows that the approval of scrubbers also appears to be in conflict with IMO air pollution rules, MARPOL Annex VI.

In 2020, the IMO set emission requirements for the sector by limiting the sulphur content of fuel oil. To comply with this sulphur cap, ships can either switch to cleaner fuels or use equivalent compliance methods. In practice, this means that ships often use scrubbers as an alternative to low sulphur fuels, which remove sulphur oxide emissions from a ship’s exhaust while allowing them to run on cheaper heavy fuel oil.

However, while scrubbers are effective in reducing sulphur oxide emissions, emissions of other types of air pollution such as particulate matter (including black carbon) and carbon dioxide are higher, compared to using lower sulphur fuels. This trade-off appears to contradict the very objective of MARPOL Annex VI which is to prevent air pollution from ships.

Further, the use of other compliance methods is balanced by the requirement that the use of such mechanisms may not impair or damage the environment and human health.

Given the severe health impacts that particulate matter and black carbon cause, and the dire effects of black carbon and carbon dioxide on the climate and the environment, further doubt is cast on the legality of scrubbers under MARPOL Annex VI.

This legal analysis was submitted to the IMO by FOEI, WWF, CSC and Pacific Environment.