Lessons Learned from the Surveillance: General Procedure for Controlling Occupational Exposure to Radon T. Beck, E. Ettenhuber Federal Office for Radiation Protection Germany

History - Radon in old mines 1898 Discovery of radium and the radium emanation by M. and P. Curie 1901 First radon measurements by Elster and Geitel in mines of Schneeberg 1920 More precise radon measurements in mines of Schneeberg and Jachymov by Lorenser and Ludewig 1936 Comprehensive investigations in mines of Schneeberg by Rajewsky et al.  1944 Average level: 100 kBq.m-3 Maximum: 500 kBq.m-3

History - Radon in uranium mines

History - Radon at workplaces other than uranium mines Since 1970 in the Ore Mountains underground mines shaft construction works works in abandoned mines show caves waterworks radon spas Since 1980 in other parts of Germany Several underground workplaces, coal mines Workplace monitoring, PAEC and radon measurements

Lessons learned from the surveillance Workplaces of concern Mines in operation including tourist mines and caves (exceptions: coal mines, salt mines) Waterworks drawing ground water Spas (small number of workplaces) Normal buildings Protection measures Limitation of the time staying in workplaces Intensive airing before start of work Systematic ventilation Engineering control Sealing of radon sources

Conception of investigations There‘s no universal panacea ! The goal of investigation governs the approach General overview on the situation Identifying workplaces of concern Decision on protective or remedial measures Planning of protective or remedial measures Success control Monitoring of workers exposure Individual measurements should be made if workers have to be systematically monitored

Action level International BSS: 1000 Bq/m³ Annual average value F: 0,4 Annual effective dose of 6 mSv Recommendations: A time-integrated radon concentrations should be specified explicitly as action level 2 . 106 Bq h m³ complies with the annual effective dose of 6 mSv (criterion for category A workers)

Optimized approach to include workplaces in the institutional control Guideline: Directive 96/29 EURATOM Identification of work activities of concern (Article 40, clause 1) Implementation of corrective measures (Article 41 a) Application of radiation protection measures pursuant to all or parts of Titles III, IV, V, VI and VIII (Article 41 b) Individual monitoring shall be systematic for exposed category A workers (Article 25, clause 1) More simple monitoring for category B workers (Article 25, clause 2)