Assessment of Indoor Radon Concentration and Its Health Impacts: Insights from a Mountainous Region

Radon is a naturally occurring radioactive gas produced by uranium decay in soil and rocks, and the dominant source of natural ionizing radiation exposure. Prolonged indoor inhalation of its alpha-emitting progeny is the second leading cause of lung cancer after tobacco smoking. This study provides the assessment of indoor radon concentrations in 25 dwellings across five villages in a mountainous region in northern Pakistan. These villages (Kamra, Thoon, Paija, Bhattian, and Chaffar) are in Kotli Sattian, a seismically active sub-Himalayan township in Rawalpindi District, Punjab, Pakistan. The CR-39 solid-state nuclear track detectors were used passively at head height for 60 days for track counting. The overall mean radon concentration was 43.75 ± 31.04 Bq∙m⁻³, ranging from 13.77 to 135.76 Bq∙m⁻³. Village-level means ranged from 33.10 Bq∙m⁻³ (Bhattian) to 51.85 Bq∙m⁻³ (Chaffar). Newly constructed concrete and brick dwellings recorded a higher mean (49.44 Bq∙m⁻³) than older mud and wood structures (35.42 Bq∙m⁻³), attributable to the elevated radium content of modern building materials. The mean annual effective dose of 0.11 mSv∙y⁻¹ is well below the 1 mSv∙y⁻¹ public limit. The Excess Lifetime Cancer Risk (ELCR) of 0.37 × 10⁻³ and Lung Cancer Risk (LCR) of 5.07 × 10⁻³ both fall within internationally accepted limits. These findings establish a radiological baseline for Kotli Sattian and highlight the need for year-round monitoring and targeted remediation in dwellings proximal to active fault structures.