Impact of microclimatic parameters on radon concentration in preschool institutions in Sarajevo Canton

Abstract

Introduction: Radon (²²²Rn), a radioactive gas produced by uranium decay, is the second leading cause of lung cancer after smoking. Indoor environments, especially preschool institutions, present increased risks due to children’s vulnerability and extended occupancy. Microclimatic parameters such as air temperature, relative humidity, and airflow are known to affect radon dynamics, but their impact in preschool settings remains insufficiently studied. This research aimed to assess the seasonal variability of radon concentrations and their association with microclimatic conditions in preschool institutions in Sarajevo Canton.

Methods: A prospective longitudinal observational study was conducted from January to October 2025 across 38 preschool institutions. Radon concentrations were continuously measured with EcoQube dosimeters, and air temperature, relative humidity, and airflow velocity were recorded with a TSI multifunctional instrument. Measurements were conducted for seven days per institution in rooms occupied by children. Statistical analyses included Wilcoxon signed-rank tests, chi-square tests, and Spearman’s correlation.

Results: Results showed that average radon levels were notably higher during winter (166.35 Bq/m³) compared to summer (84.45 Bq/m³; z = 2.074, p = 0.038). Instances of radon concentrations exceeding 300 Bq/m³ were more common in winter (10.8%) than in summer (2.7%), although the difference in their distribution was not statistically significant (χ² = 2.173, p = 0.337). A significant inverse relationship between radon and temperature was seen in summer (ρ = −0.338, p = 0.015). No significant links were found between radon and relative humidity or airflow. The seasonal variation in microclimatic factors supports their influence on radon fluctuations.

Conclusion: Radon concentrations in preschool institutions show marked seasonal variation, with significantly higher values in winter. Temperature affects radon indirectly through ventilation dynamics, while relative humidity and airflow have limited effects. Continuous monitoring and optimization of ventilation, especially during colder months, are essential to reduce radon exposure risks in preschool environments.