Quantifying indoor radon levels and determinants in schools: a case study in the radon-prone area Galicia–Norte de Portugal Euroregion

Radon is a carcinogenic compound, and is particularly concerning in the education sector, where children and teachers may be exposed even longer than at home. Thus, this study intended to characterise radon in the indoor air of scholar environments in different provinces/districts of the Euroregion Galicia–Norte de Portugal. With a pioneering approach, this study evaluated the influence of specific factors/characteristics (location, type of management, construction material, season and floor within the building) and quantified their relative contribution to indoor radon levels. Radon was continuously monitored in 416 classrooms from school buildings located in urban and rural sites from different provinces/districts both in the regions of Galicia (A Coruña and Lugo provinces) and Portugal (Porto and Bragança districts), considering rooms for different age groups (from nursery schools to universities). Single and multivariate linear regression models were built considering the radon concentrations as the outcome variable and different room/building characteristics as predictor variables. Mean and median radon concentrations were 332 Bq·m−3 and 181 Bq·m−3, respectively. The radon concentrations observed are a public health concern, as almost 1/3 of the places monitored exceeded the reference limit value of the European legislation (300 Bq·m−3). Moreover, around 50 % of the indoor levels measured could be attributed to room/building characteristics: the building's location and the main construction material, as well as the occupants' age group, the floor within the building and the school's type of management (public/private). This study concluded that radon testing is needed in all school buildings and classrooms without exceptions. Thus, public administrations are urged to dedicate funds for testing, mitigation and public dissemination initiatives in schools. A special protocol for radon sampling in school buildings should also be developedThis work was financially supported by: LA/P/0045/2020 (ALiCE) and –(LEPABE) funded by national funds through FCT/MCTES (PIDDAC); competitive scholarship from Fundación Prevent (Beca I + D en PRL). PTBS Branco thanks the Portuguese Foundation for Science and Technology (FCT) for the financial support of his work contract through the Scientific Employment Stimulus – Individual Call – 2022.05461.CEECIND. The funding sources did not have any involvement in study design; in the collection, analysis and interpretation of data; in the writing of the report; nor in the decision to submit the article for publicationS