Cleaner, low-sulphur fuels for ships could reduce the number of deaths linked will air pollution by around a third, according to new analysis.
Such fuels also have the capacity to halve the number of ship pollution-related childhood asthma cases.
Ships are major contributors to global air pollution owing to the low-grade, dirty fossil fuels used to power them, which produce 3,500 times more sulphur than the diesel fuel used by road vehicles.
High levels of air pollution from shipping have raised concerns about health impacts, particularly in ports and coastal regions. Recent Government figures revealed levels of some shipping pollutants were four times higher than previous figures had suggested.
Laurie Laybourn-Langton, director of the UK Health Alliance on Climate Change has described air pollution as having “a major effect on public health in the UK”.
He said: “Air pollutants damage our health, causing cancer, asthma, stroke and heart disease, among others.”
The new research suggested some of these health problems could be alleviated by switching to cleaner fuels, a strategy put forward by the International Maritime Organisation (IMO).
“Cleaner marine fuels will reduce ship-related premature mortality and morbidity by 34 and 54 per cent, respectively,” wrote the authors of the new study, published in the journal Nature Communications.
This amounts of a 137,000 fewer deaths due to air pollution every year, and around eight million fewer cases of childhood asthma.
By examining measures of emissions levels from around the world in combination with estimates of health impacts, the researchers were able to deduce the potential effects of different future fuel scenarios.
The IMO, which regulates shipping emissions, has proposed a reduction in the sulphur content of fuel oils used in shipping to 0.5 per cent, from the current 3.5 per cent, by 2020.
“The reduction in the limit for sulphur in fuel oil used on board ships will have tangible health benefits, particularly for populations living close to ports and major shipping routes,” said IMO's spokesperson, Natasha Brown.
However, the researchers who conducted the study, led by Dr James Corbett of the University of Delaware, said low-sulphur fuels were far from a fix-all solution.
“Despite these reductions, low-sulphur marine fuels will still account for around 250,000 deaths and around 6.4 million childhood asthma cases annually, and more stringent standards beyond 2020 may provide additional health benefits,” they wrote.
To make a significant impact on air pollution from shipping, some experts say there is a need to move beyond fossil fuels in the sector altogether.
“This is a sector with huge potential and growing commercial appetite to move to become zero-emitting both of pollutants and greenhouse gases,” Dr Tristan Smith, a shipping researcher at University College London, told The Independent.
In the Nature Communications study, the scientists noted that due to the cooling effect of sulphate aerosols – pollutants emitted by ships using fuels with high levels of sulphur – there is also a climate change angle to consider.
These aerosols have a “radiative cooling effect” that helps to reduce the planet’s temperature. This means a reduction in sulphur content would diminish this cooling effect and potentially lead to warming temperatures.
As such, they recommend an approach to air pollution that considers both climate change and human health, and pursues a reduction in greenhouse gas emissions as well as harmful pollutants such as sulphur gases.
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