Radon

What we use

Radon is a natural radioactive gas that rises from the ground and builds up in enclosed spaces. We use three sets of data, all by municipality:

• Radon priority areas, identified by the Regions and autonomous Provinces as required by the Italian radiation protection law (Legislative Decree 101/2020). In priority areas, measurements in ground-floor and basement workplaces are compulsory. We use the national list of municipalities compiled by ARPA Lombardia (the Lombardy environmental agency) from the acts of those authorities, updated to 22 July 2026. These are public acts: the report always names the authority and the act.
• Predictive emission map from ISPRA (the Italian Institute for Environmental Protection and Research), 2022, produced with the Ministry of the Environment in the Georadon project: for each municipality it estimates how much radon comes out of the ground, in four classes, from low to very high. Licence CC BY 4.0.
• Municipalities with high potential natural radioactivity from ISPRA, 2023, from the National Radon Action Plan: how much of the municipal area is made of rocks with high natural radioactivity. Licence CC BY 4.0.

How we use them

The report says whether the municipality is in a priority area, with the authority and the act that decided it, or that the Region has not yet identified the areas. It then adds the class estimated by ISPRA and the share of the municipal area with radioactive rocks. It ends with the only way to know how much radon there is in a home: measuring it, with detectors left in the rooms for a year, especially on ground and basement floors.

The most worrying of the three counts. A municipality in a priority area, or with a very high estimated emission, is critical. A high estimated emission, or radioactive rocks over at least 15% of the area, is worth considering. Otherwise the result is favourable. The meaning of the levels is in the methodology.

Who has identified the areas

As of 22 July 2026 the priority areas have been identified by Piedmont, Aosta Valley, Lombardy, the autonomous Province of Bolzano, the autonomous Province of Trento, Veneto, Friuli Venezia Giulia, Liguria, Tuscany, Apulia and Sardinia. Emilia-Romagna has not identified any municipalities in a priority area. The other Regions have not decided yet, and the report says so.

Limits

• Radon varies a great deal from one building to another: no municipal figure tells you how much there is in a home. Only a measurement does.
• A municipality outside the priority areas is not, for that reason, a municipality without radon.
• ISPRA's predictive map has no data for about half of Italian municipalities: there the report relies only on the rocks and the priority areas.
• Some authorities use more categories, for example the Province of Bolzano: the report only shows the priority areas.
• Priority areas change with each new act by the Regions: the report uses the list updated to 22 July 2026.

Official pages: ISPRA predictive map, ISPRA potential natural radioactivity and ARPA Lombardia priority areas in Italy.