# Radon Exposure

Radon-222 is a colorless, odorless, naturally occurring radioactive noble gas. It forms when uranium-238 decays in soil and rock, and it builds up in basements and ground-floor rooms of poorly ventilated buildings. When you inhale its decay products (²¹⁸Po and ²¹⁴Po), they deposit alpha-emitting particles in your bronchial lining. That causes the DNA damage that drives lung cancer. Radon is the second leading cause of lung cancer overall, after tobacco. And it is the leading cause in people who never smoked. A 2005 pooled analysis of 13 European case-control studies (7,148 cases) found an 8% higher lung-cancer risk (95% CI 3 to 16%) per 100 Bq/m³ of long-term home exposure. The WHO 2009 handbook recommends a reference level of 100 Bq/m³, and not exceeding 300 Bq/m³. Germany's Strahlenschutzgesetz (StrlSchG, in force 2018) sets a 300 Bq/m³ reference value for homes and workplaces. You can mitigate it: sub-slab depressurization, sealing, and more ventilation.

## Sources

- Darby S, Hill D, Auvinen A, et al.. (2005). Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies. BMJ. https://doi.org/10.1136/bmj.38308.477650.63
- World Health Organization. (2009). WHO Handbook on Indoor Radon: A Public Health Perspective. WHO. https://www.who.int/publications/i/item/9789241547673
- Bundesamt für Strahlenschutz (BfS). (2018). Vorschriften für Gebäude und Arbeitsplätze – Referenzwert für Radon. BfS / Strahlenschutzgesetz (StrlSchG). https://www.bfs.de/DE/themen/ion/umwelt/radon/regelungen/referenzwert.html

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