Test the home for radon
Seal cracks in floors and walls
Improve basement and crawlspace ventilation
Install a radon mitigation system
Use a sub-slab depressurization system
Vent crawlspaces with a vapor barrier
Increase air exchange with mechanical ventilation
Seal sump pits and floor drains
Maintain and inspect mitigation systems regularly
Re-test radon levels after mitigation
Use radon-resistant construction in new buildings
Hire a certified radon mitigation professional