Methodology for such administrative units that require additional investigation of radon risk was accomplished at the Geological Survey in November. The requisition for a methodology for assessing radon risk is based on the Council of European Union directive 2013/59/Euratom, which Estonia brought into use in August. It sets the reference level for guarding the health of employees, or the highest activity concentration of radon at working places.
As environmental circumstances may affect health in the long run, it is necessary to develop politics for protecting people against harmful effects of ionizing radiation. Radon investigations are essential, as WHO studies indicate that high level of indoor radon is the second most important cause of lung cancer.
In the basis of the mentioned directive, the Ministry of the Environment and the Geological Survey of Estonia rated jointly in 2016–2017 municipalities in three categories: the ones with highly likely radon risk in buildings, the ones with unlikely radon risk and such ones that do not have enough data. The directive sets 300 Bq/m3 as the reference level of activity concentration of radon in indoor air. This means that if the average concentration of indoor radon is higher than the reference level, measures for reducing it have to be taken into use.
The classification of municipalities:
I priority administrative units. It is very likely that radon risk in buildings is high. The municipalities are obliged to require that companies measure indoor radon concentration.
II priority administrative units. These areas do not have enough data for assessing radon risk.
III priority administrative units. It is very likely that radon risk is either moderate or low. These municipalities do not need to require radon measurements in company buildings.
This classification is made in the basis of the Atlas of Radon Risk and Natural Radiation in Estonian Soil, published in 2017 and basing on 15 years of collected and analysed data.
The task of the endeavour accomplished in November is to define the extent and methodology of additional radon investigations for the II priority administrative units. Such are the municipalities of Anija, Antsla, Elva, Järva, Kanepi, Kihnu, Mulgi, Ruhnu, Rõuge, Setomaa, Tõrva, Valga, Vinni and Võru, and the towns of Haapsalu, Keila, Paide, Viljandi and Võru.
The plan is to make some two hundred measuring points of soil air in 19 municipalities during the preliminary analysis. When compiling the radon atlas, the emphasis of selecting study points was in characterizing natural soil types. However, the current work focuses principally on human requirements. The majority of measuring points are planned to be located in towns and villages. One third of soil air study points will be located in the immediate vicinity of buildings, with the aim to measure radon concentration also inside these buildings. So far there are very few cases of radon measurements in soil air together with measurements of nearby buildings.
It is hoped that the planned investigations contribute in finding laws in emission of soil air radon into indoor air of buildings.
The methodology is compiled by the senior geologist Krista Täht-Kok and the maps made by the hydrogeologist Siim Tarros, both from the Department of Hydrogeology and Environmental Geology of the Geological Survey of Estonia.
