Deterministic analysis and Monte Carlo-Based Health Risk Assessment of Seasonal Radon Exposure in Groundwater and Soil of Meghalaya, India

This study investigates seasonal variations of radon in groundwater and soil, along with associated radiological risks, in Baridua Village, Meghalaya, India-a region with uranium-rich geology. Groundwater samples and soil samples (n = 30) were collected during summer (August-September 2024) and winter (January-February 2025). Radon in water was measured via emanometry, while soil radon, radium content, and exhalation rates were assessed using LR-115 detectors in sealed cans. Results revealed significantly higher mean radon concentrations in groundwater during summer (57.87 Bq L ^− 1 ) compared to winter (29.30 Bq L ^− 1 ), with 93% of summer samples exceeding the USEPA limit (11.1 Bq L ^− 1 ). Soil radon averaged 938.57 Bq m ^− 3 (summer) and 777.14 Bq m ^− 3 (winter), with radium content (3.05 Bq kg ^− 1 and 2.53 Bq kg ^− 1 ) below global averages. Health risk assessments showed that inhalation was the dominant exposure pathway, with total effective doses exceeding the WHO/UNSCEAR limit (100 µSv y ^− 1 ) in summer for adults (137.72 µSv y ^− 1 ) and children (147.46 µSv y ^− 1 ). Monte Carlo simulations indicated a 52.95% probability of children exceeding the threshold. Soil radon contributed minimally to alpha equivalent doses (< 1 mSv y ^− 1 ), though a 6% exceedance probability was noted under a worst-case scenario.