Published online by Cambridge University Press: 15 May 2009
1. Fifteen apparently healthy persons were exposed to air enriched with positive or negative ions at 78° F. and 87° F. Average ion counts at 78° F. were 12,324 positive ions per ml. and 5,451 negative ions per ml. The averages at 87° F. were 14,865 positive ions per ml. and 5,442 negative ions per ml. Relative humidity was kept at 50% and air motion was 28 ft./min.
2. Seven sensations related to comfort (thermal sensation, humidity sensation, sensible perspiration, air motion, pleasantness, mood and fatigue) were recorded, pulse rate and oral temperature were measured.
3. In the experiments at 78° F. mood was improved (P < 0·001) by positive ionization. All other qualities remained unaffected by positive ionization. No effect was found under negative ionization at the ion concentration applied.
4. In the experiments at 87° F. five sensations (thermal sensation, sensible perspiration, pleasantness, mood and fatigue) were significantly (P < 0·001) improved by ionized air. In general, as can be seen from the significantly differences between grand means, the subjects felt cooler, perspired less, felt more pleasant, were in a better mood, and felt less fatigued under the influence of air enriched with ions.
Air motion sensation, humidity sensation, pulse rate and oral temperature were not affected by ionization.
5. As different individuals may vary in their response to ionization, individual preferences were tested. These tests indicated that at 87° F. six out of the fifteen persons tested preferred ionized air (P < 0·001). One person preferred air not enriched with ions (P = 0·0091).