A radon test measures the levels of radon gas — an odorless radioactive gas — due to uranium breaking down within soil and water found present in the home. Radon gas seeps into the home through cracks in the foundation and contaminates the indoor air in your home. Inspectors can test the air inside your home using specialized devices that can detect and measure radon gas concentrations in a building. If radon levels are high, you can perform repairs and interventions to reduce those levels.