Abstract
A number of psychological and psychomotor tasks including auditory and visual reaction time, logic reasoning, mirror drawing, bead threading, rotary pursuit and digit adding, were presented to seventy-two healthy subjects, in different atmospheric conditions (temperature, ions and humidity as variables), to examine the possible role of negative air ions on circadian rhythm and human performance. Subjective ratings of both the environment and the subjects' feelings were determined. Physiological/biochemical measurements of body temperature and urinary excretion of 5-Hydroxyindoleacetic acid (5HIAA), sodium and potassium were also measured. In addition, to investigate the possible role of negative ions on perception of pain, eleven rheumatoid arthritis patients were subjected to two different atmospheric conditions: negative ions and no ions. Subjective pain assessment, subjective rating of environment and patients' own feelings were measured together with the urinary excretion of 5HIAA and 3-Hydroxyanthranilic acid (3HAA). The first chapter consists of a review of the background literature and provides a general introduction to the current study. The second chapter describes the materials and general methods used in this work. Finally, the results of the studies on negative air ions are described in the remaining three chapters. The principal findings are summarised below: Circadian rhythm; Ten human male subjects, aged twenty to twenty-seven were participants. The subjects were tested every two hours during two periods of twelve hours (09.00-21.00 hrs and 21.00-09.00 hrs). The results indicate that negative air ions have a significant effect on circadian rhythm of: sodium, potassium and 5-Hydroxyindoleacetic acid excretion in urine and also auditory reaction time and digit adding. Human performance; This work was divided into three parts; Experiment 1 had negative ions as a variable, Experiment 2 had ions and subject earthing as variables, and Experiment 3 humidity as a variable; ions present in both a 'dry' and a 'humid' environment. The results of 5-Hydroxyindoleacetic acid (5HIAA) measurements are equivocal. In all of the experiments a proportion of individuals responded to negative ions by either increasing or decreasing urinary 5HIAA excretion. The results of the psychological task performance indicate that at the room temperature employed in these experiments (29°C) only a few significant effects of ions could be demonstrated. For example, there was an improved performance at rotary pursuit (Experiment 1); improved mirror drawing in females (Experiment 2); and a reduction in visual reaction time (Experiment 3). Earthing and humidity have no effect on performance. However, corresponding to the literature more consistent effects are evident at a lower ambient temperature (e.g. 19 C). Therefore it may be concluded that the effect of negative ions on human performance depends upon the ambient temperature. Pain perception; Eleven rheumatoid arthritis patients participated. The results of 3-Hydroxyanthranilic acid (3HAA) excretion in urine indicate that eight out of eleven patients had high levels of excretion. The significant correlation between the level of 3HAA excretion and subjective pain assessment disappeared in the negative ion condition. Patients also had high pain thresholds and rated the environment more comfortable in negative ion condition. From the above results it may be concluded that negative ions, may increase the level of pain threshold and consequently, affect the perception of pain. However, the mechanisms of such an hypothetical relationship remain to be determined.