Passive systems of mitigation have been revealed to be capable of reducing indoor radon degrees by more than 50%. When radon ventilation fans are included radon levels can even be minimized further. The danger of lung cancer cells rises by 16% per 100 Bq/m3 increase in very long time ordinary radon concentration. The dose-response connection is straight-- for example, the danger of lung cancer cells raises proportionally with boosting radon direct exposure. The reduced the radon focus in a home, the reduced the danger of lung cancer cells as there is no well-known limit below which radon direct exposure carries no danger.