Radon mitigation actions in large public buildings: some review and a case study

In the last 30 years, a lot of experience in radon mitigation has been gained in many European and other countries, but even when the mitigation is not concerning single houses, it is often addressed to small buildings or to the parts of the buildings directly connected to the ground. The experience in large public buildings comes mainly in applying mitigation measures to buildings used for kindergartens and schools that are often large but not very complex: they often cover a large surface area but they generally have few floors and the structure of the building is relatively simple. Performing an adequate monitoring of radon concentration within large buildings, especially for the evaluation of mitigation effectiveness, can also be quite more difficult than for a dwelling or a small building. In Italy, several large public buildings were built more than one century ago, usually with thick walls, age-specific building details, missing or inaccurate blueprints, significant differences between blueprints and the actual situation, unknown structures (even if blueprints exist), with few information on the characteristics of building foundations and of the soil below the building. This study will present some review of remedial actions and radon concentration measurement approach in large buildings. Moreover, the mitigation system and the radon concentration monitoring system installed in one of the largest Italian public buildings (an historical building built in the 19th century) will be illustrated, together with some preliminary results.