The Italian national survey of aircrew exposure: I. Characterisation of advanced instrumentation.

The survey of aircrew exposure required the characterisation and/or the development of a diverse array of both passive and active instruments, which were not available at any one laboratory. To ensure the availability of the most advanced dosimetric systems and the relevant calibration facilities needed for the survey, an international collaboration was formed, which was facilitated by multinational research contracts promoted by the Commission of the European Communities. Close cooperation among scientists with long-term experience in different disciplines, such as cosmic ray measurement in space and radiation protection dosimetry, made it possible to exploit successfully damage track detectors for the accurate evaluation of very low fluences of particles with high energy and high charges. For a long time, the major concern for the assessment of aircrew exposure has been the accurate evaluation of the cosmic ray neutron dose. In this paper, four different dosimetric systems are considered, the response of which is sensitive to both low and high energy neutrons. All these dosimetric systems have provided consistent results when exposed together to the high energy beam facility at CERN, which is considered to approximate the cosmic ray field.

The Italian national survey of aircrew exposure: II. On-board measurements and results.

The Italian survey of aircrew exposure has been carried out with different advanced dosimetric systems, as described in part I of this paper. The key strategy of the survey was to obtain on-board comparison of measurements for both passive and real-time detectors flown together with passengers. The survey has been carried out in the period of solar minimum (1995-1997), in which the exposure to galactic cosmic rays reaches its maximum value. Even though carrying out the survey in the period of solar minimum was entirely coincidental, this circumstance has been used to good advantage to obtain a comprehensive set of data of the galactic cosmic radiation with little or no disturbance by the solar activity modulation. This comprehensive set of data covers flight routes between -20 degrees and 75 degrees geographic latitude at different civil aviation altitudes. The survey obtained with different advanced dosimetric systems has been supplemented by a large variety of data gathered with passive stacks on different short-range and long-range flights at supersonic and subsonic altitudes. Some of the most important conclusions which can be drawn from the survey are: (i) aircrew of civil aviation receive annual doses within the range of 1 mSv to 6 mSv; (ii) data from different periods of solar minimum agree well, since the discrepancies encountered seem mainly due to the different dosimetric systems used; (iii) repeated measurements on the same route are highly consistent.

Results of the representative Italian national survey on radon indoors.

A representative national survey on population exposure to radon in Italian dwellings was carried out from 1989 to 1994, with the co-operation of the National Health Service. The measurements were performed by 19 Regional Laboratories, all using the same techniques and protocols. A stratified, two-stage sampling procedure was used to sample families. The sampled families were approached door-to-door to maximize response. To optimize the quality of the measurements, two dosimeters, each containing two alpha track detectors, were placed together in one room (typically the bedroom) for two consecutive 6-mo periods. The distribution of annual radon concentration was derived from measurements in 4,866 dwellings. The average value is 75 Bq m(-3) and the fractions of dwellings above the reference levels of 150, 200, 400, and 600 Bq m-3 are 8.7%, 4.7%, 1.0%, and 0.2%, respectively. The geometric mean is 57 Bq m-3 while the geometric standard deviation is 2.0. The average values in the Italian Regions fall within the 20-120 Bq m-3 range. When the average radon concentration is examined vs. story, building materials seem to play a significant role. The average lifetime risk of lung cancer for chronic radon exposure of Italian population at home would be about 5 x 10(-3), using the risk factor proposed by the ICRP in 1993.

Recent results (1986-1989) on the ENEA quality assurance programme for the radioactivity surveillance network in Italy.

A programme for the Quality Assurance of the Italian network for surveillance of radioactivity in foodstuff and environmental samples was started by the ENEA in 1983. The main purpose of this programme is to establish uniform levels of accuracy and reproducibility in measurement procedures routinely used by the laboratories belonging to the network. This paper describes the technical aspects relevant to the calibration and intercomparison campaigns carried out, in Italy, in the period 1986-1989. The relevant measurements include gamma spectrometry and beta-ray counting in liquid aqueous samples.

Activity measurements of Sr-90 and Cs-137 in spiked solutions of milk. Results of a national intercomparison in Italy.

A national intercomparison was organized by ENEA for activity measurements of 90Sr and 137Cs in spiked solutions of milk. The participants in the intercomparison were the laboratories belonging to the Italian network for control of radioactivity in the environment. The purpose of these measurements was to check the reliability of measurement procedures and experimental means as routinely used by each participant. This first intercomparison showed appreciable discrepancies among the participants and this was due both to improper procedures and non correct calibrated spectrometers. Soon after a second intercomparison was carried out to check to what extent the previous results were reproducible among the various participants. Methods and results are discussed.

Feasibility study of radiation protection guidelines in the use of building materials in the Italian dwellings.

The Italian situation concerning the indoor radiation exposure is examined. A tentative comparison of the risk connected with radon and radon daughter indoor exposures and other every day life risks is made. The social economic impact of imposing possible constraints on home building industry is also discussed.