Logistic of surveys of retrospective radon concentrations by home-stored CDs/DVDs.

Recently, a method for rather precise retrospective (222)Rn measurements, based on home-stored compact disks (CDs)/DVDs, has demonstrated a promising potential for wide application. In Bulgaria, pilot surveys have been initiated based on voluntarily provided CDs/DVDs. The results showed that large-scale surveys could be efficiently organised. However, several problems were identified and are discussed in the report. The first is the relatively small proportion of participants (30-50 %) that actually provided disks. Other addressed topics include the compatibility between results of different disks from one place, the accuracy of dating CDs/DVDs and the possibility for individual a posteriori calibration of each disk. The possibility to follow year-to-year variations by disks of different age is also discussed.