Test their home. They have two options. They can buy a do-it-yourself test kit or they can hire a certified professional. If the levels are high, take action to reduce, because it's easy. The cost is similar to other home maintenance costs. It's similar to a new air conditioner or a new furnace, and it will reduce your radon by up to 80% to 90%.
On June 18th, 2015. See this statement in context.