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Proceedings of the 5th Conference on Protection against Radon at Home and at Work. September 9-15, 2007. Prague, Czech Republic.

Although the chronicles of radon history go back several centuries and many new technologies and findings have emerged, especially in the past hundred years, we are still far from a satisfactory finale. Naturally occurring radioactivity is a topic that has evoked interest and concern among scientists in recent years because of a shift in the focus from highlevel radiation originating from nuclear bomb testing to a commonly found phenomenon in our environment which is, on average, responsible for 50% of the effective dose received by ordinary people. The issue of assessing the effective dose of radon and its progeny was taken as the main topic of the 5th Conference on Protection against Radon at Home and at Work. This Conference already has a 10-y tradition. The first in the series was organised by Prof. Julien Garsou and Prof. H. W. Vanderschueren in Brussels in 1995. Prague has continued the tradition, and two International Conferences dedicated to radon problems have now been held at the Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague (the first in 2004). The International Workshop on the Geological Aspects of Radon Risk Mapping, which takes place regularly at 2-y intervals in Prague, is well known in the international radon scientific community. The Conference was truly international, with 80 participants from 25 countries. The participants represented a wide range works related to radon issues: scientists who have dedicated most of their professional life to radon measurement and/or theory, geologists, civil engineers, epidemiologists and, of course, some young people who will, we hope, expand our ‘radon family’. This assortment of interested parties contributed to a fruitful exchange of experience, confronting different types of opinions and viewpoints throughout the conference week. Our concept for the Conference encompassed not only lectures and poster sessions but also panel discussions, an opportunity to compare devices in a modern radon chamber, and the comprehensive final workshops. The main topic of the workshop held in the Bozkov dolomite cave was ‘Measurement of radon and radon progeny in caves’. The other workshop, held in the Bohemian Forest, was dedicated to ‘Indoor measurement and radon diagnostic methods’ and ‘Radon risk classification of building sites’. The Conference provided an opportunity for participants to familiarise themselves with the latest developments in instrumentation and to see presentations from exhibitors and sponsors. The scientific programme of the conference comprised seven invited lectures, one special lecture, two workshops, one panel discussion, 38 oral lectures, 22 poster presentations and a video conference with the 17th National Radon Conference in Jacksonville (AARST). The implementation of the ‘telebridge’ with Jacksonville was a memorable experience for us. Communication between two lecture halls, one in Europe and the other in the USA, via an Internet connection was the result of strenuous efforts by both organising committees. Both sides presented up-to-date information on the status of the radon programme in their own countries. Many thanks to Jiri Hulka for representing Europe so well, and to Harry Friedmann for being an inspiring host. Our sincere thanks to Steve Couch and Bill Angell. We hope to repeat this link next time, and to establish a tradition. The organisers would like to express their thanks to all the participants who worked hard to perfect their presentations, the best of which are published in this special issue. Thanks are due to all members of the ‘superb technical team’ that supported the Conference and created the well thought-out and efficiently functioning ‘invisible’ machinery of the Conference. The organisers hope that the following pages will serve the reader as a useful and welcome review of the topics and as helpful reference materials for the future study of radon issues. The 5th Conference on Protection against Radon at Home and at Work was faultlessly organised by