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The University of Southampton
Southampton Marine and Maritime Institute

New paper questions impact of new IMO fuel regulations on shipping emissions and their health effects

Published: 25 February 2020
Matt Loxham

This new paper authored by SMMI member Matt Loxham and Prof Kate Lewins, from Murdoch University, Perth discusses the past, present, and future of regulations on shipping fuel sulphur content, centring around Annex VI of the IMO’s MARPOL (International Convention for the Prevention of Pollution from Ships, 1973 as modified by the Protocol of 1978), with a particular focus on regulation and enforcement around the world. In particular, it focuses on new regulations to be introduced in 2020, tightening sulphur limits in much of the worlds’ oceans and seas (although still less stringent than regulations in EU ports and in the English Channel, North Sea, and Baltic Sea).

The paper also focuses on particulate emissions from ships, and the analysis of evidence on the effects of reduced fuel sulphur on particulate emissions, with a special focus on the potential health effects of those emissions. Matt and Kate suggest that, while the overall mass of PM emissions from ships, and the concentrations of certain metallic elements and organic carbon species, is likely to be diminished by use of lower sulphur fuel, there is some evidence that, under certain conditions, the number of particles released may increase, and that this may especially apply when engines are running as they might in port, rather than on the open seas. These increased numbers of particles are almost exclusively in the ultrafine fraction of PM, particles smaller than 100 nm in diameter, which are hypothesised to pose a particular risk to health because of their huge surface area and ability to enter the circulation through the lungs. Furthermore, exhaust cleaning technology which may be used instead of lower sulphur fuel is of doubtful efficacy in removing these ultrafine particles.

Therefore, the new sulphur regulations may have mixed effects on components of PM thought to be associated with adverse health effects, meaning that overall health benefits cannot be assured.

The paper casts doubt on the IMO premise that regulating shipping fuel for sulphur content would also adequately regulate PM. The decision to regulate PM ‘by proxy’ in this way appears to be a lost opportunity. There are no PM reduction targets for shipping and therefore little incentive to invest in technologies or mechanisms to reduce PM. 


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