Sources: Earth and rock beneath home; well water; building materials.

Health Effects: No acute symptoms.  Estimated to cause about ten percent of lung cancer deaths.  Smokers are at higher risk of developing radon induced lung cancer.

Steps to reduce Radon exposure: Test your home for radon; Get professional advice before planning and carrying out radon reduction measures; Seal cracks and other openings in the basement floor; Ventilate crawl space; Treat radon contaminated well water by aerating or filtering through granulated activated charcoal. 

Radon Exposure in Texas 
EPA Recommendations Regarding Radon