Swedish Residential Case Control Study
1360 cases, 2847 controls (male & female).
Average Radon Concentration = 2.9 pCi/L.
Compared to individuals whose home exposure averaged below 1.4 pCi/L.
Found 30% increased risk with average home radon concentrations of 3.8-10.8 pCi/L.
Found 80% increased risk with average home radon concentrations above 10.8 pCi/L.
2 separate control groups increases confidence in validity.