EXAGGERATED RESPONSES TO CHLORINE INHALATION AMONG PERSONS WITH NONSPECIFIC AIRWAY HYPERREACTIVITY

Although chlorine gas is a common irritant exposure, little is known a bout airway responses to chlorine inhalation among persons with baseli ne airway hyperreactivity. We wished to determine whether such persons manifest an exaggerated response to chlorine compared with normal sub jects. We studied 10 subjects, five with and five without airway hyper responsiveness (HR) after exposure to 1.0 ppm chlorine and five person s, all with HR, to 0.4 ppm chlorine. After 1.0 ppm inhalation, there w as a significant (p<0.05) fall (mean+/-SE) in FEV(1) immediately follo wing exposure among normal (-180+/-37 mt) and HR subjects (-520+/-171 mt). The fall was greater among the HR compared with the normal subjec ts (p=0.04). Specific airway resistance (Sraw) increased to a greater degree among the HR group compared with normal subjects (p=0.04). Amon g all subjects (n=10), the proportional change in FEV(1) after 1.0 ppm chlorine correlated with baseline reactivity (Spearman rank correlati on r=0.64, p<0.05). At 24-h follow-up, there were no significant chlor ine-related pulmonary function deficits. After 0.4 ppm chlorine inhala tion, there was no significant pulmonary function effect. These data i ndicate that persons with hyperreactive airways manifest an exaggerate d airway response to chlorine at 1.0 ppm. This suggests that when larg e numbers of persons are exposed to chlorine, a susceptible subpopulat ion may acutely respond, with a greater decrement in pulmonary functio n.