Environmental Ionization in Enclosed Geospheres: Comparative Study of Global and Local Measurements (2018–2025)

Abstract

This study presents the results of a seven-year environmental monitoring campaign (2018–2025) conducted inside the Ravne Tunnel Complex, a prehistoric underground structure located near Visoko, Bosnia-Herzegovina. Biannual measurements were carried out using calibrated scientific instruments to assess air ion concentrations and related microclimatic parameters. The results reveal consistently elevated levels of negative air ions (NAI) across all internal locations—ranging from 10,000 to over 300,000 ions/cm³—with a peak value of 330,000 ions/cm³ recorded in late 2023. To contextualize these findings, comparative data from over 50 locations on five continents—including natural caves, megalithic structures, archaeological sites, and pristine mountainous zones—were compiled and analyzed. The Ravne Tunnel Complex consistently exhibits negative ion concentrations that are an order of magnitude higher than those recorded in even the cleanest natural outdoor environments, which typically range between 100 and 5,000 ions/cm³. Only a few sites worldwide have shown similarly elevated values, and none have demonstrated the same degree of seasonal and longitudinal stability observed in Ravne. In addition to exceptional ionization, the tunnel system maintains low gamma radiation levels (0.06–0.10 µSv/h), no detectable electromagnetic radiation (0.00 mW/cm²), consistently breathable oxygen concentrations (19.0–20.9%), and high relative humidity (77–88%) without artificial intervention. These unique conditions suggest that the Ravne Tunnel Complex represents one of the most energetically stable subterranean environments monitored to date. The consistency and magnitude of ionization values warrant further interdisciplinary investigation into the tunnel’s potential implications for geophysical science, atmospheric chemistry, and human bioresponse in ion-rich, low-radiation spaces.