Ships pollute half as much as world’s cars

Since most shipping traffic takes place close to the coastline, ship emissions are a significant health concern.

Globally, commercial ships emit almost half as much particulate pollution into the air as the total amount released by cars, according to a new study1. Ship pollutants affect the Earth’s climate, ecosystems, and the health of people.
Based on direct measurements of emissions, it is estimated that worldwide, ships emit 900,000 tonnes of particulate matter (PM) pollution each year. Shipping also contributes up to 30 per cent of smogforming nitrogen oxides (NOx), and 5-8 per cent of global man-made sulphur dioxide (SO2) emissions.
“Since more than 70 percent of shipping traffic takes place within 250 miles (400 kilometres) of the coastline, this is a significant health concern,” says lead author Daniel Lack, a researcher at the National Oceanic and Atmospheric Administration (NOAA) in Boulder, Colorado.
Lack and colleagues have analyzed the exhaust from over 200 commercial vessels, including cargo ships, tankers and cruise ships. They have also examined the chemistry of particles in ship exhaust gases.

Ships emit sulphates − the same polluting particles associated with diesel-engine cars and trucks that prompted improvements in on-road vehicle fuel standards. Sulphate emissions from ships vary with the concentration of sulphur in ship fuel. Globally, ship fuel sulphur content is regulated under the International Maritime Organisation (IMO). Some ships use cleaner low-sulphur fuel oils, while most others continue to use high-sulphur heavy fuel oils.
   According to the new study, sulphates make up just under half (46%) of shipping’s total particle emissions. The other half is composed of organic particles (39%) and sooty, black carbon particles (15%).
   Both the sulphate particles and the organic particles appear to be linearly correlated with fuel sulphur content, Ships pollute half as much as world’s cars Jeff Clow /Fotol ia and fuels with higher sulphur contents produce more small particles than fuels containing less sulphur.
   An earlier study by Lack’s team found that emissions of the non-sulphate particles depend on the operating speed of the engine and the amount of lubricating oil needed to deal with wear and tear from burning less-refined fuels.

One surprising result of switching to low-sulphur fuels is that, although total particle emissions diminish significantly, the time that remaining emitted particles spend in the air appears to increase. The organic and black carbon particles are less likely to form cloud droplets. As a result, these particles remain suspended for longer periods of time before being washed to the ground through precipitation.

1 Particulate emissions from commercial shipping: Chemical, physical, and optical properties. By Lack, D. A., et al. (February 2009). Journal of Geophysical Research, 114, D00F04, doi:10.1029/2008JD011300

In this issue

Reduced pollution from petrol stations

New legislation will require service stations in the EU to be equipped with petrol vapour recovery, resulting in improved protection of the environment and public health.

EU states postpone air quality compliance

Nineteen member states have so far notified the Commission that they will need time extensions to comply with EU air quality standards.

Top of the dirty thirty list

Having spewn out 31 million tonnes of carbon dioxide (CO₂) in 2008, the Polish Belchatow plant is listed as EU’s most polluting power station in terms of its greenhouse gas emissions. The German Niederaussem power plant was the second dirtiest and emitted nearly 25 million tonnes.

A push for cleaner industry

The new Industrial Emissions directive received its first reading in the European Parliament in March, and the Council position is expected at the end of June.

Transport emissions still on the increase

Greenhouse gas emissions from the European transport sector rose 26 per cent between 1990 and 2006, while all other sectors show a declining trend.

Particles cost billions

Health damage in Sweden from fine particle pollution costs SEK 26 billion (€ 2.4 billion) every year, according to a recent study prepared for the Swedish Environmental Protection Agency.

Small but dangerous - new facts on particles

Fine particles cause 546,000 premature deaths each year in Europe, of which 39,000 are due to emissions from international shipping.

Worse than worst case...

Carbon dioxide emissions from fossilfuel burning and industrial processes is accelerating not only in industrialized countires, but at a global scale. The emissions growth rate has been over 3 per cent for the present decade, compared to 1.1 per cent during the 1990s.

Greenhouse gas emissions from rich countries still increasing

Almost half of the signatory states to the Kyoto protocol have reached their emission targets. Still overall grenhouse gas emissions is increasing. The USA alone was responsible for over two thirds of the increase in 2007.

Shipping would profit by cutting CO2 emissions

Greenhouse gas emissions from the global shipping industry could be cut by at least one fifth without any cost or even at a profit.

Environmental ship index underway

On request from several leading ports in northwestern Europe, including Le Havre, Antwerp, Rotterdam, Bremen and Hamburg, the Dutch research institute CE Delft has developed an environmental ship index to be implemented voluntarily from 2010 to promote greener shipping.