Using physiological indices to consider the effects of negative air ions on the human body

Negative air ions are known to activate cell functions, stabilize the emotional state, and induce recovery from fatigue by preventing acidification of blood and accelerating metabolism. Generators of these negative air ions have recently been incorporated in household appliances such as air-conditioners. However, evaluation of their effects has not been sufficient; there are only a few related reports. In this study, we measured electrodermal activities and the skin blood flow as indices of effects of negative air ions on the autonomic nervous system and cardiovascular system, respectively, by allowing the subject to inhale negative air ions at 7,000 particles/cm3 or 20,000 particles/cm3. Although no significant changes were noted in electrodermal activities, our results suggested that negative air ions have effects on physiologic activities including autonomic activities.