Centre for Radon

Head: Doc. Dr. Janja Vaupotič

The radioactive noble gas radon with its short half-life decay products contributes on average more than half to the annual effective radiation dose that we receive from natural sources. The decay products of radon are a greater threat than radon itself. Gaseous radon is exhaled, but its decay products are metals that in air mostly take the form of aerosols. These are filtered from air in the lung and deposited on the epithelia of the respiratory tract. The energy released from the alpha, beta and gamma decay of these particles is absorbed by the surrounding tissues, damaging them. This may lead to cancer.

Radon (Rn-222) is formed in the Earth’s crust by radioactive decay of radium in the uranium 238 decay chain. Its half-life is 3.86 days, which makes it possible for radon to enter the atmosphere either by diffusion or convection. In the ground its concentration is usually from 50 to several 100 kBqm−3, depending on ground composition (the concentration of radionuclides of the uranium decay chain) and ground structure (porosity). In the air radon is rapidly dispersed and the concentrations rarely exceed 50 Bq m−3. The situation is different, however, in closed spaces like houses, apartments and other buildings. If the floors and walls of buildings are not adequately built and insulated, radon enters enclosed spaces. In inside air the concentrations of radon are several 100 Bq m−3 and in some cases they may reach several 1000 Bq m−3.

Based on the recommendations of some international health organisations, many countries have set the maximum allowed concentrations of radon in air. These are usually in the range of 200-600 Bq m−3 for homes and 500-1500 Bq m−3 for workplaces. In Slovenia the average annual concentrations of radon in air are 400 Bq m−3 in homes and 1000 Bq m−3 in workplaces.

Research areas

• Research on radon and its short lived decay products in the air of living and workplaces (homes, kindergartens, schools, spas, underground caves, mines…)
• Identification of radon sources
• Dosimetry of radon
• Temporal and spatial distribution of radon in different media (air, surface and ground waters, sea water)
• Research on anomalies in radon concentrations and changes in geochemical and geophysical parameters in ground air and thermal waters in connection with seismic activity
• Development of methods for measuring low concentrations of radon in air and water

We also collaborate in the educational process as post-graduate lecturers and supervisors for master’s and doctoral theses in the following institutions:

• The Jožef Stefan International Postgraduate School
  • Ecotechnology
• The University of Nova Gorica
  • School of Environmental Sciences
  • Graduate School
• Medical Faculty of the University of Ljubljana
• Faculty of Civil Engineering of the University of Maribor

Important research

• 1990-1994 The Slovenian National Programme of Radon Measurements:
  • 730 kindergartens
  • 890 schools
• 1000 apartments
• 1995-2004 Radiological Monitoring of Postojna Cave
• 1996-2002 Research on radon at specific workplaces:
  • 5 of the largest Slovenian spas
  • 10 plumbing companies
  • 7 commercial wine cellars
• 1997-2004 Additional research in kindergartens and schools:
  • sources of radon, doses received by children and employees (123 buildings) and remediation work (35 buildings)
• 1998 Radon anomalies in connection to earthquakes:
  • measurements in ground air and thermal waters
• 2003 Distribution of radon in sea water
• 2004 Measurements of radon in open spaces (60 sampling points throughout Slovenia)

Staff:

• Dr. Janja Vaupotič
• Asta Gregorič, PhD student