When the air breaks down into radon gas, radon daughters can enter the airways and lungs. Where they come apart and cause radioactive exposure, especially by alpha radiation, the lung tissue. Epidemiological surveys among miners know that exposure to high radon concentration continues caused an increase of lung cancers.
Radon concentration in soil is high and penetration to buildings, infrastructure through open ground, can cause high radon concentration and dangerous buildings. The second source of radon in buildings is to vent it construction materials. Because of health risk, in all advanced countries there is legislation and law enforcement on radon concentrations in buildings.