2024 Yes https://www.sciencedirect.com/science/article/pii/S0969804323005079?via%3Dihub Dosh, Rukia Jaber Europe Exposure Study Elementary (K-5) Radon Thoron Thoron Pin-hole dosimeter method CR-39 detector Annual effective dose Primary schools Al-Najaf city The results of the average value of thoron concentration detector, the annual effective dose (AED), Excessive Lifetime Cancer Risk (ELCR) x 10-3, and Lung Cancer Case (LCC) x 10-9 measured in the building of the schools were 7.47 +/- 2.85 Bq/m3, 0.03 +/- 0.01 mSv/y, 0.11 +/- 0.04, and 0.54 +/- 0.20, respectively. All the results of indoor thoron were below the global average limit. The results of the radiological survey due to thoron concentrations for studied primary schools suggest that the radionuclides and their radiological hazard indexes in all studied schools in AL Najaf city, Iraq, do not impose a health hazard.