S Darby et al. Scand J Work Env Health (2006) Vol.32 supp1 p 1-16.
“Residential Radon and lung cancer – detailed results of a collaborative analysis of individual data on 7148 persons with lung cancer and 14,208 persons without lung cancer from 13 epidemiological studies in Europe.”
For lifelong non-smokers, the risks of lung cancer at 100 Bq/m³ and 400 Bq/m³ were estimated to be 1.2 and 1.6 respectively, relative to no radon exposure. For those smoking 15 – 20 cigarettes per day the relative risk of lung cancer would be 25.8 at 0 radon exposure, 29.9 at 100 Bq/m³ and 42.3 at 400 Bq/m³.