The Mont Blanc massif, predominantly granitic and rich in Uranium, is the natural source of radon gas. The beauty of these rock faces visually tells the geological origin of the risk.
Radon Gas Aosta Valley
Aosta Valley Radon:
11 Priority Areas Municipalities
The Region has officially released the list of 11 Risk Municipalities (Priority Areas) with DGR 1630/2025. If you run a business in Courmayeur, Gressoney or the Great St. Bernard Valley, radon measurement is now mandatory even on the ground floor. Discover how to comply with Legislative Decree 101/2020 and protect health in the workplace.
The Radon Issue in Aosta Valley
The new Priority Areas defined by DGR 1630/2025.
Aosta Valley Regulatory References
With **DGR 1630/2025** published on January 27, 2026, the Aosta Valley Region implemented Art. 11 of Legislative Decree 101/2020 identifying the **'Priority Areas'**. The technical survey, conducted by **ARPA Valle d'Aosta** through measurement campaigns in 45 out of 74 municipalities and a radio-geo-lithological model for uncovered areas, identified 11 specific Municipalities characterized by granitic geology with high radon emission.
Monitoring and environmental data
DGR n. 1630/2025
The New 2025 Classification
With the publication of **DGR 1630/2025** on January 27, 2026, the Aosta Valley Region fully implemented Article 11 of Legislative Decree 101/2020, officially releasing the list of Municipalities falling within **Priority Areas**. This classification is not random but the result of an in-depth investigation: **11 specific Municipalities** have been identified where estimates confirm that at least 15% of the building stock exceeds the average annual concentration of **300 Bq/m³**. The scientific methodology adopted by ARPA Valle d'Aosta combines direct data from widespread measurement campaigns in 45 municipalities with an advanced radio-geo-lithological model for risk estimation in unmonitored areas. This makes the radon map in Aosta Valley an essential tool for territorial planning and health protection.
Geology: The Primacy of Alpine Granite
Aosta Valley holds a geological primacy that directly influences **indoor air quality**: it is one of the regions with the highest average radon concentrations in Italy. The reason lies in the very nature of the Alps, consisting mainly of granitic massifs and porphyritic rocks rich in **Uranium-238**, the progenitor of radon. The particular morphological conformation of the valleys accelerates this phenomenon: in the valley floors, **thermal inversion** favors the accumulation of gas rising from the subsoil, trapping it in the lower layers of the atmosphere and facilitating its entry into buildings through cracks and uninsulated crawl spaces. For this reason, **radon measurement** is essential in almost the entire regional territory, not just at high altitudes.
Obligations: Monitoring Triggered on Ground Floor
In the **11 designated Municipalities**, monitoring becomes mandatory for **all workplaces on the ground floor and semi-basement**, in addition to underground premises already obligated throughout the territory. Hotels, B&Bs, mountain huts, shops, restaurants, and schools must measure radon annually.
Historical Path of Radon Regulations
From the 2013 European Directive to the 2025 VdA Resolution: evolution of the legal framework.
Directive 2013/59/Euratom
The BSS Directive (Basic Safety Standards) establishes fundamental safety standards for protection against ionizing radiation, including radon gas. It introduces for the first time at the European level the reference level of 300 Bq/m³ for workplaces and dwellings.
Read on EUR-LexD.Lgs July 31, 2020, n. 101
The Consolidated Law on Radiation Protection implements the Euratom Directive in Italy. It introduces mandatory obligations for employers, defines **Priority Areas**, establishes the **National Radon Action Plan (PNAR)** and provides for criminal penalties for non-compliance (Art. 205).
Preparatory Activities and ARPA Studies
Pending regional implementation, ARPA Valle d'Aosta conducted widespread monitoring campaigns in 45 out of 74 municipalities, creating a predictive model based on geology (uranium-bearing lithologies) to cover the entire territory and identify areas at greatest risk.
Go to ARPA VdA websiteNational Radon Action Plan
The strategic document (PNAR 2023-2032) coordinating the Regions. Fundamental for long-term remediation strategies and prevention in new constructions.
DGR n. 1630/2025
It is the fundamental implementing provision. Published on January 27, 2026, the Resolution approves the list of 11 Municipalities in Priority Areas, triggering the measurement obligation extended also to **ground floor** and semi-basement premises. It defines deadlines and operating procedures for measurement in work activities and schools.
Download Resolution (PDF)Aosta Valley Radon Map: Priority Areas 2026
Official radon risk cartography and regional territory classification according to DGR 1630/2025.
The Aosta Valley Region has identified radon risk areas in implementation of Art. 11 of Legislative Decree 101/2020. The methodology used by ARPA is based on the results of measurement campaigns carried out in 45 municipalities (out of a total of 74) and on a radio-geo-lithological model to estimate concentrations in areas not covered by experimental measurements.
This first identification also included municipalities with an estimate between 10% and 15%, which should have been classified as priority areas starting from 2028. The list may be updated in the future based on new measurement campaigns.
Regional map highlighting municipalities: Red (Priority Area ≥15%), Yellow (Attention Area 10-15%), White (Other municipalities).
LEGEND
Municipalities where it is estimated that at least 15% of buildings have average annual radon concentrations exceeding 300 Bq/m³.
Municipalities where the estimate is between 10% and 15%. Preventively classified as priority areas.
Radon measurement obligation only for underground premises (D.Lgs 101/2020).
Source: ARPA Valle d'Aosta / DGR 1630/2025.
The Valle d'Aosta Region has identified radon risk areas in implementation of Art. 11 of Legislative Decree 101/2020. The methodology used by ARPA is based on the results of measurement campaigns carried out in 45 municipalities (out of a total of 74) and on a radio-geo-lithological model to estimate concentrations in areas not covered by experimental measurements.
This first identification also included municipalities with an estimate between 10% and 15%, which should have been classified as priority areas starting from 2028. The list may be updated in the future based on new measurement campaigns.
List of the 11 Municipalities in Priority Areas
Aosta Valley municipalities officially classified as Priority Areas with DGR 1630/2025.
Source: ARPA Valle d'Aosta - DGR 1630/2025 (January 27, 2026)
| Municipality | Geographical Zone |
|---|---|
| Avise | Valdigne |
| Bionaz | Valpelline |
| Courmayeur | Mont Blanc |
| Gressoney-La-Trinité | Lys Valley |
| La Salle | Valdigne |
| Oyace | Valpelline |
| Rhêmes-Notre-Dame | Rhêmes Valley |
| Saint-Oyen | Great St. Bernard |
| Saint-Rhémy-en-Bosses | Great St. Bernard |
| Valsavarenche | Gran Paradiso |
| Villeneuve | Valdigne |
Radon Measurement Obligations in Aosta Valley
What the regulations provide for employers, schools, and accommodation facilities.
Monitoring Triggered on Ground Floor
In the 11 designated Municipalities (including Courmayeur and Gressoney), monitoring becomes mandatory for all workplaces on the ground floor and semi-basement, in addition to underground premises already obligated throughout the territory. If you manage a commercial activity, an office, or a facility open to the public in these areas, you are required to certify the healthiness of your environments.
Tourism and Schools: Maximum Alert
The legislation is particularly severe for facilities hosting people for prolonged periods. Hotels, B&Bs, alpine huts, restaurants, schools, and kindergartens fall fully within the annual measurement obligations. Guaranteeing radon-free air is not just a bureaucratic requirement to avoid criminal penalties, but a mark of quality and safety you offer to your guests, students, and workers, protecting them from an invisible but concrete risk.
How to Comply?
The procedure is simple but rigorous: it is necessary to place passive dosimeters (small and non-invasive instruments) for a period of 12 months. This timeframe is necessary to average the strong seasonal variations typical of the alpine climate. At the end, an accredited laboratory will issue the test report valid for legal purposes. Do not wait for an inspection: prevention is the only effective defense.
Frequently Asked Questions about Radon in Aosta Valley
Answers to the most common questions about obligations, measurements, and regional regulations.
Which are the radon risk municipalities in Aosta Valley?
Why is Aosta Valley at risk for radon?
Who must measure?
What is the legal limit?
Does ARPA VdA offer free measurements?
How long does the measurement take?
Do I need to measure if I have a B&B or hut?
Are old houses more at risk?
How to remediate a house in the mountains?
What do I risk if I don't measure radon?
Business in Aosta Valley?
Get compliant with Legislative Decree 101/2020.