Intermittent exposures to enhanced air-ion concentrations for improved comfort and increased productivity?

Much information and several hypotheses have appeared in print concerning the influence of air ions on the health and comfort of man. Yet still our understanding is confused. In a month-long, double-blind trial, 18 normal, healthy adults were exposed intermittently to enhanced concentrations of negative air ions in their working environments. Evaluations of well-being and perceptions of air quality were deduced from answers to a questionnaire completed twice daily by the subjects. After their exposure to enhanced negative air-ion concentrations, the subjects' assessments of both their own well-being and the quality of the environment improved significantly: neither harmful effects of exposure to enhanced levels of negative air ions nor changes in perceived thermal comfort were detected. These findings are consistent with the serotonin hypothesis, which was proposed by Krueger and Smith in 1960.