Clinical and laboratory features of acute sulfur dioxide inhalation poisoning: two-year follow-up.

We present clinical and laboratory results (including nuclear imaging) obtained over a period of two years in two nonsmoking miners who were exposed to high concentrations of sulfur dioxide (SO2) after a mine explosion. Within 3 wk of the accident, both miners had evidence of severe airways obstruction, hypoxemia, markedly reduced exercise tolerance, ventilation-perfusion mismatch, and evidence of active inflammation as documented by positive gallium lung scan. Serial ventilation-perfusion scans over the first 12 months showed progressive improvement without returning to normal. After the initial recovery, there has been no significant change over the subsequent two years postinjury. Pulmonary function and exercise tests also displayed a similar pattern of initial improvement. We conclude that (1) acute exposure to high concentrations of SO2 results in severe airways obstruction, (2) pulmonary function abnormalities are partially reversible, and (3) most of the improvement occurs within 12 months after the initial injury.