IDK I stay out of radiation zones unless I have a hazmat suit or power armor + helmet which specifically say they completely protect you from radiation.
Radiation is basically limited to craters, municipal reactors + wearhouse (BN), silos, hazardous waste sarcophagus, and a few other common sense places. The only time I ever encounter radiation without specifically preparing for it is due to the zombie scientist’s rad-beam attack which, frankly isn’t of any concern to me.