source of radioactive gaseous radon in homes
1 The main source of indoor radon is radon gas infiltration from soil into buildings. 2  Rock and soil produce radon gas. 3  Building materials, the water supply, and natural gas can all be sources of radon in the home. 4  Basements allow more opportunity for soil gas entry than slab-on-grade foundations. Rock and soil produce radon gas. 2  Building materials, the water supply, and natural gas can all be sources of radon in the home. 3  Basements allow more opportunity for soil gas entry than slab-on-grade foundations.