How sea air may not be good for you after all...and in fact leave you breathing in noxious chemicals

The Lincolnshire seaside resort of Skegness attracted many visitors in the first half of the century thanks to a 1908 poster celebrating the quality of its sea air.

But scientists have warned that a coastal stroll could mean breathing in noxious chemicals.

Lure: The iconic Skegness poster

Smoke from vessels at sea or in port is affecting the air quality of coastal cities, they said.

Researchers identified 'primary sulphate' in ship emissions, consisting of tiny sulphur particles less than 1.5 microns across.

Breathed in, they can lodge deep inside the lungs and pose a serious health hazard.

Some scientists believe they may cause lung cancer.

Primary sulphate, or S04, is produced when ships burn a cheap sulphur-rich fuel called 'bunker oil'.

The particles are believed to be especially harmful to human health because of their small size.

Dr Gerardo Dominguez, a member of the UCSD team, said the research showed that the potential risk from ship emissions was important and should not be ignored in the future.

It is estimated that ship pollution may be responsible for up to 60,000 deaths a year worldwide.

U.S. scientists from the University of California at San Diego found ships emitted far more sulphate than previously realised.

Their analysis, published in the journal Proceedings of the National Academy of Sciences, separated primary sulphate from ship smoke and other sources.

Air samples showed 44 per cent of the sulphate polluting coastal California could be traced to ships.

Britons also have cause to be concerned as the English Channel is the world's busiest shipping corridor, with hundreds of ships passing the South coast every day.

Professor Mark Thiemens, who led the study, said the findings were a surprise: 'This is the first study that shows the contribution of ships to fine particulates in the atmosphere.

'Ships are really unregulated when it comes to air pollution standards. What we wanted to find out was the contribution of ships to the air pollution in San Diego.

'And what we found was a surprise, because no one expected that the contribution from ships of solid sulphur-rich particles called primary sulphate would be so high.'

From July next year, all tankers, cargo and cruise ships sailing into Californian ports will have to switch to more expensive, cleaner fuels when they come within 24 miles of the coast.

Similar international rules are due to take effect in 2015.