Air crews `the most exposed to radiation' of any occupation

Air crews working on transatlantic flights receive more exposure to radiation than the typical nuclear power-plant worker, according to new research, and twice the exposure of ground-based staff.

The exposures come from naturally occurring cosmic ray radiation which reaches us from deep space, explained Prof Denis O'Sullivan, of the Dublin Institute for Advanced Studies, who was in charge of the EU-funded research effort. "I was asked to co-ordinate the research because I have a background in cosmic rays."

The project involved scientists in Britain, Germany, Sweden, Austria and at CERN, Europe's high energy physics research centre. Special equipment was placed on short- and long-haul flights by participating airlines including Aer Lingus, and radiation levels were measured. Prof O'Sullivan presented his research yesterday at the 11th International Congress of Radiation Research, which was organised by the Dublin Institute of Technology.

"Cosmic rays originate outside our solar system and they envelop the whole solar system," Prof O'Sullivan said. They are "very high energy particles" which break up when they strike the atmosphere or other materials and cause a cascade of particles which together cause the ionising radiation exposure.

We are all bombarded by cosmic rays all the time but the thicker sea level atmosphere mops up more of them than is the case for high-flying aircraft. Radiation is measured in thousandths of Sieverts (mSv) and an average ground exposure from all natural radiation sources might reach 2mSv a year.

Transatlantic pilots and attendants flying 600 hours a year would be exposed to double this amount and staff working longhaul flights to South America or South Africa might reach three times this amount, Prof O'Sullivan said. Short flights to London or the Continent would add about one mSv to the natural background levels over the course of a year.

"Air crews are the most exposed to radiation of any occupation, even more than radiation workers," he said. "There is obviously concern for pregnant aircrew."

It was still not considered a major problem, he added, although the European Commission had put together regulations to be introduced next year which would limit the exposures for air crews. It proposes an exposure ceiling of six mSv a year, reduced to half this amount for pregnant staff.

Prof O'Sullivan said the research could not have been done without the involvement of CERN, which provided baseline measurements which were then compared with the data collected during flights.

Conference delegates heard a presentation on the naturally occurring radioactive gas, radon. Dr Evan Douple of the US National Academy of Sciences said research indicted that 10 per cent of all lung cancer deaths were caused by exposure to radon, making it the second most important cause of lung cancers after smoking.

About 1,500 people die of lung cancer each year in Ireland and so about 150 deaths could be attributed to radon exposure.