Thorax 1984;39:594-596 Effect of positive ionisation of inspired air on the response of asthmatic children to exercise

ABSTRACI To evaluate the effect of positive ionisation of inspired air on bronchial reactivity, 12 asthmatic children were twice challenged by exercise in random order. During one test positively ionised air (5-10 x 105 ions/cm) was breathed. All challenges were matched in terms of basal lung function and exercise tests were matched in terms of ventilation and respiratory heat loss. Exercise induced asthma was significantly aggravated by exposure to positively ionised air, the postexercise fall in FEV1 (A FEV,) being 24*7 % (SEM and 5.3%) and 35-3 % (5%) after the control and ionised air tests respectively (p < 0.04). It is concluded that positive ionisation aggravates the bronchial response to exercise. Asthmatic subjects are characterised by increased airway reactivity when exposed to various stimuli, both specific ones such as antigen inhalation and non-specific ones such as physical exertion. ' 2 The ionic charge of the air has for long been thought to affect various biological systems,34 including the respiratory system, which is highly exposed to air constituents.56 Uncontrolled studies in the past have suggested a beneficial effect of nega-tive ions on lung function in asthmatics but the observed changes were always minor.78 Recently we studied the effect of negative ionisation of inspired air on the response of asthmatic children to exercise and inhaled histamine.9 We found that negative ion-isation significantly attenuated the response to exer-cise but the effect on histamine responsiveness was more variable. To investigate this further we decided to study the response of asthmatic children to exercise while they were breathing positively ion-ised air under similarly controlled conditions. Methods Twelve asthmatic children, seven of them boys, with a mean age of 12 (range 9-15) years participated in this study. All were known to have had asthmatic attacks provoked by physical exertion. Children an