Lowering the sulphur content of fuel used in shipping could prevent upwards of 45,000 premature deaths a year by reducing exposure to fine particles.
Lowering the sulphur content of fuel used in shipping could prevent upwards of 45,000 premature deaths a year by reducing exposure to fine particles, according to a study published recently.
Ship emissions of sulphur oxides are directly related to the sulphur content of the fuel oil. For ocean-going vessels, fuel sulphur content averages around 2.7% with an upper limit as high as 4.5%.
Once emitted, sulphur oxides react with other pollutants in the air, such as nitrates or ammonium, to form very small particles. Moreover, the burning of high-sulphur heavy fuel oils also results in higher emissions of so-called primary particles (particulate organic matter and black carbon), as compared to using lower-sulphur distillate fuels, i.e. diesel oil and gas oil. Fine particles, which are less than 2.5 micrometres across, are thought to be the most hazardous group of particles, and have been linked to cardiopulmonary disease and lung cancer.
In an earlier research paper, two of the co-authors of the current study concluded that pollution from international marine shipping in 2002 caused approximately 64,000 premature cardiopulmonary and lung cancer deaths around the world each year (see AN 4, 2007). In that paper, they estimated that the annual mortalities from ship emissions could increase by 40 per cent by 2012, to nearly 90,000 deaths.
In this new study, a 2012 “No Control” scenario (assuming 2.7% fuel sulphur content) was compared with three emission control scenarios. Two of these represent cases where marine fuel sulphur content is limited to 0.5% and 0.1% content, respectively, within 200 nautical miles (370 kilometres) of coastal areas. A third emission control scenario represents a global limit of 0.5% sulphur content.
Requiring ships either to use marine fuel with a maximum of 0.5% sulphur globally or alternatively 0.1% sulphur content within 200 nautical miles (nm) of coastal areas, could reduce annual premature deaths by around 45,000 by 2012, i.e. approximately 50 per cent of the 87,000 deaths estimated to occur in the no control scenario. A limit of 0.5% sulphur within 200 nm could reduce the number of premature deaths by about 34,000.
According to the authors, these results confirm that meaningful benefits are achieved from either a 0.5% or a 0.1% sulphur control strategy. The study demonstrates the clear benefits of reducing sulphur emissions globally, not just in coastal regions, as particles can be carried long distances in the atmosphere. It also shows that stricter limits within Emission Control Areas (see box) will bring additional health benefits.
The premature mortality impacts demonstrated by the study are only two of many impacts that are related to shipping emissions and fuel quality, the authors point out. Climate change, acidification, visibility, eutrophication, and other envir-onmental effects are also closely related to the type of fuel used in ships.
Christer Ågren
International ship emission regulations The International Maritime Organization (IMO), under ANNEX VI of MARPOL 73/78 (the International Convention for the Prevention of Pollution from Ships), has adopted controls on sulphur in marine fuels.The global fuel sulphur limit is currently 4.5%, and will be reduced to 3.5% in 2012 and then further lowered to 0.5%, but not until 2020. In specially designated sulphur emission control areas (SOx-ECAs), the current limit is set at 1.5% sulphur. It will be tightened to 1% by July 2010 and to 0.1% by 2015.
There are currently only two existing SOx ECAs, the North Sea and the Baltic Sea. Earlier this year, the USA and Canada proposed that IMO should designate most areas of their coastal waters (within 200 nautical miles of coastal areas) as an ECA. The proposal is expected to be approved by IMO in March 2010.
Note that exhaust gas cleaning systems (e.g. scrubbers) that achieve equivalent sulphur emission reductions may be used as an alternative to low-sulphur fuels.
Source: Mitigating the Health Impacts of Pollution from Oceangoing Shipping: An Assessment of Low-Sulfur Fuel Mandates. By J. Winebrake, J. Corbett, E. Green, A. Lauer and V. Eyring. Published online in the American Chemical Society journal Environmental Science & Technology on 3 June 2009. Volume 43, No. 13, pp 4776–4782.