Geological radon map
The official classification groups radon by whole municipalities. This map goes down to the ground: it shows the probability that the soil beneath each location releases radon, based on the lithology of the Continuous Geological Map (GEODE) by IGME.
Two buildings in the same municipality can sit on very different ground. This layer is informative and does not replace the official CTE DB-HS6 classification or the workplace radon obligations. Only measurement confirms the radon in a building.
Explore the geology at your location
Tap the map to see what lies beneath a specific point. The grey lines mark the municipal boundaries.
Geology guides, it does not decide: 54% of homes measured above 300 Bq/m³ lie in higher-probability areas, and 4% of those in lower-probability areas exceed that level. Construction quality and building age also matter: two buildings on the same ground can give very different readings.
This map is indicative. Even if it shows lower probability, if your company or your new building is in a Zone II municipality, measuring remains mandatory. Check the obligations: CTE regulation · Workplace regulation
With the map focused: arrow keys to pan, + and - to zoom.
Geological probability of elevated radon
- Higher probability — Felsic rocks: phonolites, trachytes, trachybasalts (A)
- Higher probability — Clays and lacustrine soils (C)
- Lower probability — Basaltic rocks and basanites (B)
- Lower probability — Deposits: sands, alluvium, debris (D)
- Lower probability — Mixed igneous rocks without clear predominance (M)
Methodology and sources
This map applies the lithological classification criterion defined in the following study, not its full methodology, which additionally combines terrestrial gamma radiation measurements: Briones, C., Jubera, J., Alonso, H., Olaiz, J., Santana, J.T., Rodríguez-Brito, N., Arriola-Velásquez, A.C., Miquel, N., Tejera, A., Martel, P., González-Díaz, E., Rubiano, J.G. (2024). Indoor radon risk mapping of the Canary Islands using a methodology for volcanic islands combining geological information and terrestrial gamma radiation data. Science of the Total Environment, 922, 171212. doi.org/10.1016/j.scitotenv.2024.171212
Geological cartography: GEODE, Geological and Mining Institute of Spain (IGME). Data origin: ©CN Instituto Geológico y Minero de España (IGME). Date of access: July 2026.
Municipal boundaries: © Instituto Geográfico Nacional (CC BY 4.0).
Own work. This map does not come from the cited authors nor is it endorsed by them.
See also the regulatory map
Legal obligations depend on the official municipal classification of the CTE DB-HS6, both in construction and in workplaces.
Request your radon measurement
Standard measurement
Radtrak3® detector for 3 months. The most precise and reliable measurement to determine the annual average radon concentration.
Quick measurement
Rapidos detector for 10-90 days. Results in less time, but less representative than the 3-month measurement.
This measurement is indicative. For reliable results, we recommend the 3-month standard measurement.
