To evaluate whether residential radon exposure explains the excess mortalit
y for lung cancer in an Italian alpine valley with high natural radioactivi
ty, the authors conducted a population-based case-control study on 138 dece
ased cases and 291 sex- and year-of-birth-matched controls. Year-long alpha
-track measurements of radon were performed in the most recent residence, a
nd information about occupational history and lifetime smoking habits was o
btained. The authors adjusted for smoking, and radon was associated with lu
ng cancer risk among men: compared with a radon level of < 40 becquerels (B
q) per cubic meter (m(3)), the odds ratios for 40-76 Bq/m(3), 77-139 Bq/m(3
), 140-199 Bq/m(3), and 200+ Bq/m(3) were 2.1, 2.0, 2.7, and 1.4, respectiv
ely. The association between radon and lung cancer, as determined with a mu
ltiplicative model, was found only among male smokers.