Effects of accidental chlorine inhalation on pulmonary function

In an industrial accident, 19 previously healthy workers were briefly exposed to high concentrations of chlorine gas. Pulmonary function tests were done at intervals for about two years but complete follow-up data were available in only 11 subjects. Immediately following the exposure, airway obstruction was detected in 10 of 19 patients; 700 days later this was found in only 3 of 11 patients. Two of these three patients had a history of smoking, however. The mean residual volume was 141% +/- 97 (mean +/- standard error of the mean) on day 1. In subsequent follow-up studies, the residual volume progressively fell in all patients, and 700 days later the mean residual volume was 90% +/- 5. In 5 of the 19 subjects, all pulmonary function test results were within normal limits on day 1. Apparently in some subjects acute exposure to chlorine gas may cause immediate changes in the lung functions, but these changes gradually resolve. Because of the small number of patients in our series, however, the long-term effects of chlorine are less apparent.