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A research study carried out by Helmholtz Zentrum Munchen (The German Research Center for Environmental Health) has reached the conclusion that requiring ships to use exhaust gas scrubbers and particle filters would be a more effective way to protect human health than imposing a new limit on the maximum sulphur content of marine fuel.

The Munich team, led by Professor Ralf Zimmermann, in a follow-up study to one carried out in 2015, has looked at how macrophages in the lungs are affected by ship exhaust gases. Macrophages are said to be much more sensitive than lung epithelial cells and therefore react more strongly to exposure.

"Macrophages are known as scavenger cells of the immune system and respond more sensitively to particulate matter in the lungs than lung epithelial cells, since they are the 'first line of response' against foreign invaders in the lungs such as germs or even fine dust particles," said Sean Sapcariu, first author of the study and doctoral student at the University of Luxembourg, a cooperation partner of the Helmholtz Virtual Institute of Complex Molecular Systems in Environmental Health (HICE).

The scientists found that fine particles from heavy fuel oil (HFO) emissions had a stronger effect on the development of pro-inflammatory reactions than particles emitted from diesel ship engines, but the latter more strongly influence other fundamental biological processes such as DNA-, RNA- and protein-synthesis.

"We then found that the emitted particles both from the heavy fuel oil and from the diesel exhaust had similarly high toxic effects on the macrophages. Surprisingly, the toxic effects leading to cell death are even slightly lower in the heavy fuel oil emissions, although the concentrations of known toxic pollutants in the heavy oil emissions are much higher," Zimmermann added.

The study concluded, therefore, that the proposed heavy fuel oil ban is "probably less beneficial than expected for protecting the health of people in coastal areas".

"The simplest and safest way to mitigate these adverse health effects from ship engine emissions would be to introduce efficient particle reducing measures such as exhaust gas scrubbers and particle filters. These would precipitate the harmful fine particles from the emissions and thus reduce the adverse health effects, irrespective of the fuel used. Since such measures are generally not implemented on a voluntary basis, in our view there is an urgent need for action by policy makers in government and by national and European regulatory authorities," the study added.

The report comes just three months before the International Maritime Organization's (IMO) Marine Environment Protection Committee (MEPC) is scheduled to meet between 24th and 28th October to determine whether the global 0.5% cap on sulphur in marine fuel is to be implemented in 2020 or delayed until 2025.