Mapping indoor radon hazard in Germany: The geogenic component

Area of Science:

• Environmental Science
• Public Health
• Geology

Background:

• Indoor radon (Rn) is a significant indoor air pollutant with carcinogenic effects.
• The primary source of indoor radon is the ground beneath residential buildings.
• Accurate prediction of indoor radon levels is crucial for public health protection.

Purpose of the Study:

• To predict the geogenic component of indoor radon hazard in Germany.
• To assess the number of residential buildings exceeding established radon concentration thresholds (100 Bq/m³ and 300 Bq/m³).
• To evaluate the effectiveness of geogenic radon potential (GRP) and geogenic radon hazard index (GRHI) in predicting indoor radon levels.

Main Methods:

• Utilized a dataset of 44,629 indoor radon measurements across Germany.
• Linked indoor radon data with maps of geogenic radon potential (GRP) and geogenic radon hazard index (GRHI).
• Applied logistic regression models to estimate exceedance probabilities and coupled these with building stock data to quantify affected buildings.

Main Results:

• The geogenic radon hazard index (GRHI) proved to be a better predictor of indoor radon hazard than GRP.
• Approximately 2 million residential buildings (~11.6%) exceed 100 Bq/m³, and ~350,000 (~1.9%) exceed 300 Bq/m³.
• While high-risk areas (300 Bq/m³ exceedance >10%) are geographically small, most hazardous indoor radon concentrations are found in low to medium hazard regions.

Conclusions:

• The geogenic radon hazard index (GRHI) is a valuable tool for predicting indoor radon risk in Germany.
• Current radon protection strategies, like the radon priority area concept, are cost-efficient but may not cover all high-risk buildings.
• Effective lung cancer risk reduction requires addressing indoor radon in low to medium hazard areas, not solely focusing on designated priority zones.