2021 No https://www.sciencedirect.com/science/article/abs/pii/S1438463921000572 Dovjak, Mateja Europe Observational Epidemiology Study Elementary (K-5) Radon Effective dose Radon Ventilation rate School Renovation Simulations showed that the highest radon concentrations were observed in case 1 with a DVR of 79.6 m3/h (621 Bq/m3) and case 4 with a DVR of 69.4 m3/h (711 Bq/m3), both defined by national regulations. The calculated values in both cases exceeded the national reference value for radon (300 Bq/m3) by 2.1 times and 2.4 times, and the WHO guideline value (100 Bq/m3) by 6.2 times and 7.1 times, respectively. The simulations are in line with the results of radon dosimetry. Both DVRs correspond to the highest effective doses, 1.88 mSv/y (about 14-fold higher than expected effective dose) for case 1 and 2.15 mSv/y (about 17-fold higher than expected effective dose) for case 4. Case 11_Cat I with a DVR of 1999.7 m3/h defined by EN 15251: 2007 resulted in minimal Rn concentration (35 Bq/m3) and corresponds to the lowest effective dose 0.11 mSv/y and its ratio to the expected effective dose 0.8.