This is an excellent point: we do not have precise control of ion dosage. All we really know is the ion flow rate of the generator; all the other factors you list will modulate what the person actually receives (the “dose”). CET’s recommended apparatus was designed to maximize flow to the subject — and thus reduce dose variability — by addition of a grounded wrist strap. The vagaries of dosing aside, however, there are important reasons to seriously consider this new treatment modality:nnFirst, ion generators with high flow rate in close proximity to the subject have produced significant antidepressant results relative to low flow rates. Second, the treatment appears to be innocuous — not only is ion “dose” imperceptible,–no disturbing side effects have been found thus far in controlled clinical trials. To generalize a bit further, consider that a standard “dose” of medication taken in pill form will result in vastly different blood (and brain) concentrations from person to person. Same thing with light therapy: when we measure how many lux a person receives at a light box, it varies significantly between people and indeed within a session for each person.