Redpine Home Inspections Inc, recommends every property to have a radon test completed before close, even if one is already installed. 50% of homes in Colorado have high radon levels, think about that. Every home should be tested every few years as levels change from time, area being developed, water aquifers underground changing. All kinds of things can cause levels to change.Homes may be subject to contamination by Radon, a colorless, odorless, radioactive gas listed by the US Environmental Protection Agency (EPA) as being the second-leading cause of lung cancer in the US. Radon decay products may modify, damage or destroy cells or DNA in human lungs.