By Roger Harrabin BBC environment correspondent

Ships use fuel with a high sulphur content

European environment ministers are facing calls to reduce the amount of air pollution from ships.

A conference on marine protection - taking place in Germany on Wednesday - is being told that ships give off as much sulphur as all the cars, lorries and factories in Europe put together.

By 2010, up to 40% of air pollution over land could come from ships.

Airborne sulphur is a major cause of acid rain that harms crops and buildings.

It also forms particles which are breathed deep into people's lungs and shown to increase the risk of heart attacks and respiratory problems.

Governments have made laws to achieve huge cuts in sulphur from cars, buses, lorries, factories and power stations.

But ships have evaded legislation, partly because they appeared to be a relatively minor source and partly because of the complexity of addressing an international industry based across many countries, some of them outside of Europe.

Emission cuts

Ships now fill up with bunker fuel which is very cheap but high in sulphur.

"They use the waste products from the refinery, so the refineries make clean fuel for cars, for inland boats, and the rest they simply dump into the tanks of ships going to sea," says Irene Blooming, a spokeswoman for the European environmental coalition Seas at Risk.

A ship lets out around 50 times more sulphur than a lorry per metric ton of cargo carried.

Countries like the UK promised six years ago that they would cut emissions from shipping by ratifying a clause in a marine treaty but they have not done it yet.

Now the European Parliament is demanding that the EU insists that ships make emission cuts of 80% to protect people living near the coasts.

Ms Blooming welcomed the move.

"I'm very confident that we can realise this," she said.