Air pollution from ships

Illustration of a blue ship with lots of smoke

This page provides background information on the health and environmental impacts of air pollution from ships. It also highlights the measures that can be taken to significantly reduce SOx, NOx and fine particle emissions from ships with recommendations for EU action.

How much air pollution does shipping cause in Europe?

In 2000, in the seas surrounding Europe (the Baltic Sea, the North Sea, the North-Eastern part of the Atlantic, the Mediterranean and the Black Sea), sulphur dioxide (SO2) emissions from international shipping were estimated at 2.3 million tonnes a year, nitrogen dioxide (NOx) ones at 3.3 million tonnes, and particulate matter (PM) at 250,000 tonnes. In a business as usual scenario, these emissions are expected to grow by 40 to 50% by 2020.

How much and how fast can pollution from ships be cut?

Technical measures to cut air pollution from ships by 80 to 90% are easily implementable. The benefits would considerably outweigh the costs involved. These include the adoption of cleaner fuels, adding 'scrubbers' or other exhaust gas cleaning devices to ships and wider use of alternative sources of energy, including wind power and port-side electricity.

Why is it important to pay more attention to ship emissions?

Air pollution emissions from ships are continuously growing, while land-based emissions are gradually coming down. If things are left as they are, by 2020 shipping will be the biggest single emitter of air pollution in Europe, even surpassing the emissions from all land-based sources together.

How do SO2, NOx and particle emissions pose a threat to human health?

Air pollution from international shipping accounts approximately for 50,000 premature deaths per year in Europe, at an annual cost to society of more than €58 billion according to recent scientific studies. Through chemical reactions in the air, SO2 and NOx is converted into fine particles, sulphate and nitrate aerosols. In addition to the particles directly emitted by ships such as black carbon, these secondary particles increase the health impacts of shipping pollution. Tiny airborne particles are linked to premature deaths. The particles get into the lungs and are small enough to pass through tissues and enter the blood. They can then trigger inflammations which eventually cause heart and lung failures. Ship emissions may also contain carcinogenic particles.

Implementing the sulphur standards for shipping fuels that the International Maritime Organization (IMO) adopted in 2008 is expected to save 26,000 lives a year in the EU as from 2020.

How much would reducing air pollution from ships cost?

The costs for reducing pollutant emissions from shipping are estimated within a range between 0.5 and 4 euros per kg of SO2 and from 0.01 to 0.6 per kg of NOx. Reducing emissions from the same pollutants from land-based sources would cost more, as there have already been substantial reductions in this respect in the last thirty years.

In any case, reducing air pollution from ships is a very cost effective solution. Up to 34 billion Euros could be saved in health costs each year if the IMO fuel standards were transposed into the EU legislation. These savings do not take into consideration the benefits for ecosystems and the environment as a whole if acidification and other negative consequences of air pollution were reduced.

What are the new sulphur standards agreed at the IMO level and in the EU?

In 2008, the UN International Maritime Organization (IMO) revised its standards on the sulphur content of marine fuels (contained in MARPOL Annex VI). In October 2012, the standards were officially transposed in Europe. Under the current EU regulations:

  1. From 2015, ship sailing in the Sulphur Emission Control Areas (SECAs) cannot use fuel with more than 0,1% of sulphur. European SECAs currently include the Baltic Sea, the North Sea and the English Channel;
  2. Globally, ships have to cut their fuel's sulphur content to a maximum of 3.5% in 2012 and to 0.5% in 2020. While the latter limit is subject to review at the IMO, the EU decided to firmly stick to the implementation date of 2020;
  3. In Europe only, passenger ships sailing outside SECA will have to respect a limit of 1,5% sulphur fuels, which was set in 2005.
  4. Different compliance methods are offered to shipowners. Instead of using marine diesel, shipping operators can choose to switch to LNG-fuelled ships or to cut their sulphur emissions by fitting engines with scrubbers or other exhaust gas cleaning technologies. 

What standards are in place to reduce NOx emissions from ships?

The IMO MARPOL Annex VI has also strengthened the standards relating to NOx emissions, with NOx emissions to be cut by 16-22% as from 2011 compared to 2000 levels, and by 80% in 2016.

However, while the sulphur limit values apply to the entire fleet, the NOx emission limits only applies to new ships and the strictest limit (Tier III to be applied in 2016) only applies to new ships sailing in designated areas, the NOx Emission Control Areas (NECAs). The Helsinki Commission – grouping the nine countries with Baltic coastlines – and the EU have agreed to apply to the IMO for stricter NOx emissions limits to apply in the Baltic. The application is expected to be considered by the IMO’s marine environment protection committee (MEPC 70) in October 2016 along with a parallel application for an ECA in the North Sea and English Channel.

Shipping in the Baltic Sea causes more than 13,000 tonnes of airborne nitrogen to be deposited each year, worsening the existing problem of eutrophication.

Moves to have NOx included in the Baltic ECA were first discussed in 2007, but a series of environmental and economic studies to justify the NOx limits have taken several years to complete and in 2014 Russia failed to join its Helcom partners in agreeing to go forward with an application to the IMO. This coincided with Russian moves to delay the Tier III implementation dates for all NECAs which resulted in the fixed date in MARPOL for new ECAs to apply to North America only. As a consequence, under the forthcoming Baltic and North Sea applications, ‘Tier III’ NOx requirements for new ship engines would apply only from 2021.

The only way to effectively tackle NOx emissions in Europe will be to adopt a regulation that would also address the existing fleet, which is responsible for the bulk of emissions. A levy on nitrogen oxides (NOx) emissions with revenues earmarked to fund the uptake of NOx abatement measures is the most promising tool to reduce these ship emissions by up to 70%. .In addition to a NOx levy with a fund, mandatory slow steaming of ships (with a levy and fund as an alternative compliance option) and a stand-alone levy on emitted NOx could also deliver emission reductions. Read our briefing here.

What technological improvements will the industry have to put in place to cut air pollution from international shipping?

The industry has at its disposal a wide range of options and techniques to cut pollution, most of which are already available on a large scale and easily implementable. These include:

  • Using low sulphur fuels: it's the easiest way of reducing pollutants from ships. Shipping fuels currently have almost 3.000 times the sulphur content of fuels used in road transport in Europe. Also, low sulphur fuels make the ship's engine run smoother and with less operating problems and maintenance costs. Last, but not least, using low sulphur fuel reduces other pollutant emissions.
  • Scrubbers: a possible alternative to low sulphur fuels, they would cut emissions of SO2 by 99% and considerably reduce emissions of other polluting particles, but there are still some concerns about the by-products they produce in the cleaning process.
  • Internal engine modifications - such as water injection and exhaust gas recirculation: these are techniques to prevent NOx production during the combustion process, and can abate NOx emissions by 30 to 50%.
  • Humid air motor: by adding water vapour to the combustion air, NOx emissions could be cut by 70 to 85%.
  • Selective catalytic reduction (SCR): a system to treat exhaust gases after their production but before they are actually emitted. SCR can cut NOx by up to 95%. It's already used in some 500 ships worldwide and works better with low sulphur fuels.
  • Gas engines: Ship engines can work with liquified natural gas (LNG) which doesn't contain sulphur and therefore has SO2 emissions close to zero. Gas engines also dramatically reduce other PM emissions. Although it's easier to fit new ships with such engines, conversions have already taken place.
  • Shore-side electricity: can be used while ships are at the port and could cut SO2, NOx and other PM emissions by up to 90%.
  • Alternative energy sources: Experiments with wind and solar power, biofuels and fuel cells are ongoing and could be useful in the future.

What should the EU and Member States do to reduce air pollution from ships?

Transport & Environment has formulated a series of recommendations for the EU and its member states. These include:

  • Transposing the international standards for NOx emissions into EU law and adopt regulation in Europe to address the NOx emissions of the existing fleet.
  • Extending the SOx Emission Control Areas in the EU (e.g. in the Mediterranean, in the Black Sea, in the Irish Sea and the North East Atlantic) and designate NOx Emission Control Areas as soon as possible.
  • Monitoring that proper enforcement procedures are adopted in Europe in order to ensure compliance with the standards.
  • Adopting market-based measures to make polluters pay a fair price for the emissions the shipping sector is responsible for.