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Radiation exposure accounts of aircrews

Monitoring the exposure rate at exposed working places

15.03.2000

[jes] Passengers flying from Frankfurt to Fairbanks, Alaska, get more of it than those heading for Johannesburg, South Africa. The natural cosmic radiation falling on the earth differs according to flight route, flight altitude and flight duration. Within the framework of a European project, the Physikalisch-Technische Bundesanstalt (PTB) investigated new measuring methods and collected data of the radiation burden at flight altitudes. Using these data and computer calculations as a basis, airline companies can in future predict the burden of their flying personnel and minimize it by suitably planning the routes and duty rosters. The PTB will present some of its radiation meters at the Hannover Fair, not only meters for measurements at flight altitudes but also meters for measurements on the ground.

Radiation is omnipresent. It emerges from the ground, hits us from the space, comes from the materials used to build our houses or assists the physicians in diagnosis and therapy. On an average, each citizen of the Federal Republic takes up an annual dose of 4 millisievert (mSv), medical applications such as X-raying, computer tomography or iodine treatment making up about one third of this sum. This annual value may, however, be quite different for the individual citizen: the radiation burden at exposed working places, for example in radiation medicine, in nuclear plants or in mines, or just the burden of flying personnel, can also reach some millisievert and must be added to the annual basic burden. New European laws prescribe that all working places at which the limiting value of 1 mSv per annum is exceeded must be specially monitored.

On numerous intercontinental flights, during a total of about 200 flying hours, PTB experts - in cooperation with colleagues from the Austrian research centre in Seibersdorf (near Vienna) and the Deutsche Lufthansa - precisely measured the radiation burden as a function of flight altitude and geographical location using specially developed detectors. The measurement curve exactly shows the increase of the dose rate between equator and the poles and as a function of the flight altitude. From the measurement results it follows that pilots and stewardesses who spend several hundred hours per year in airplanes easily take up an additional dose of more than 1 mSv/year. Computer programs which were tested using, among other things, the data measured by PTB, can now predict the radiation dose for any desired route with an uncertainty of only 10 to 15%. The airline companies thus have a tool at their disposal which enables them to take precautionary measures in order to protect their personnel from radiation hazards: they can keep "radiation exposure accounts" for the individual staff member and correct the duty schedules of members with especially high radiation burden, if necessary.

Additional information:
At the Hannover Fair (March 20 to 25, 2000)
PTB stand (Hall 18, stand B 020, telephone at the Fair: +49 (0)511 89-438 04)

Dr. Ulrich Schrewe, telephone: +49 (0)531 592-7311; e-mail:ulrich.schrewe(at)ptb.de
"Dosimetry of Cosmic Radiation" project
Physikalisch-Technische Bundesanstalt (PTB)