Assessment of İndoor Radon Levels and Annual Effective Dose Across University Campus: A Case Study from Kırşehir Province, Turkiye

Abstract

This study presents a campus-wide assessment of indoor 222Rn at Kırşehir Ahi Evran University (Central Anatolia, Türkiye), providing a measurement-based baseline for both the main campus and affiliated off-campus facilities. Indoor radon was monitored using CR-39 passive solid-state nuclear track detectors deployed across the main campus and the university's facilities in Kaman, Mucur, and Çiçekdağ, covering 46 measurement points within 17 buildings for at least three months. Radon activity concentrations ranged from 13 to 99 Bq/m3 (overall mean: 32.46 Bq/m3; median: 26.5 Bq/m3); 58.7% of measurement points were below 30 Bq/m3, and none exceeded 100 Bq/m3. Substantial spatial heterogeneity was observed between buildings and across floor levels. Basements exhibited the highest mean concentration (∼52.1 Bq/m3), yet several buildings showed non-monotonic vertical profiles, indicating that ventilation practices and room-specific entry pathways may override simple height-dependent trends. Based on building-mean values, the annual effective dose ranged from 0.124 to 0.550 mSv/y (mean: 0.270 mSv/y), corresponding to an excess lifetime cancer risk (ELCR) of 0.434 - 1.925 × 10-3 (mean: 0.944 × 10-3). Overall, these findings provide an institutional baseline to support follow-up monitoring and targeted ventilation optimisation.