COSMIC-RADIATION DOSES RECEIVED BY AUSTRALIAN COMMERCIAL FLIGHT CREWS AND THE IMPLICATIONS OF ICRP-60

In response to concerns expressed in the aviation industry, surveys of the cosmic radiation doses received by Australian commercial flight crews were carried out in 1982-1983 and in 1991. Dose rate measurements were made by use of thermoluminescent dosimeter personal monitors, CR-39 disks, and portable monitoring equipment. The results indicated that the average annual doses to domestic crew members were between 1.0 and 1.8 mSv. They further indicated that an increase in annual doses had occurred since 1983. A method of estimating doses from flight records was developed and the results compared favorably with the measurements from both surveys. By use of this method, annual doses up to 3.8 mSv were estimated for international crew members. This represented a significant increase since 1983. It is doubtful that the average doses received by either group would comply with the ICRP Publication 60 public limit of 1 mSv y(-1) averaged over 5 y. ICRP Publication 60 recommended that the new occupational annual dose limit of 20 mSv should now apply to flight crews. This represented a dose limit of at least four times that which was previously permitted. In view of the general trend to lower dose limits, the nature of the occupation, and given that annual doses were found to be < 5 mSv, the use of an annual dose limit of 5 mSv is suggested for Australian commercial flight crews.