Radon is thus assumed to be the second leading cause of lung cancer after smoking, and accounts for 15,000 to 22,000 cancer deaths per year in the US alone.
氡是造成肺癌的第二個主要源因，數量緊追在抽菸的數目之後，單單在美國就造成每年15,000至22,000人因癌症而死亡。