“Travelers who show signs of radiation sickness are being referred to health authorities for proper treatment.”
Does this mean there are passengers actually showing signs of radiation sickness??
That’s certainly how one would read it, though it could just be a statement of policy/procedure.
However, it is theoretically possible some Japanese passengers had substantial exposure if they were close to Fukushima. The trace particulates they are picking up at the airport are in way too low a range to generate any immediate, visible symptoms, so a serious exposure, if any, would have to have happened at or near Fukushima, either a very hot local plume or an unshielded gamma event. Without more knowledge of their exact travel pattern, it’s hard to know.
Also keep in mind some symptoms of stress greatly resemble some stages of serious exposure (nausea, lightheadedness, etc.), and airport security would have to give any such complaints a worst case presumption, by design.