Radon is a colorless, odorless, and tasteless gas that can be harmful if accumulated inside a building. There are two main ways of mitigating this problem, the passive and the active. In the passive method, a physical barrier is laid between the soil and the foundation and a vent pipe extending from the sub-slab up to the roof.
In active form, there is a setup of electric vent fan, vent pipe extending from sub slab to roof, sealed cracks in the foundation, and a system failure warning device. For detailed information about radon gas and its preventive methods go through this infographic from PropertEco.