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

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

3. History - Radon in uranium mines

4. 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

5. 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

6. 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

7. 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
Bq h m³ complies with the annual effective dose of 6 mSv (criterion for category A workers)

8. 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)