Health status and sulfur dioxide exposure of nickel smelter workers and civic laborers.

We examined a group of 143 nickel smelter workers who processed a high sulfide ore, and compared their health status with that of 117 civic laborers. All subjects were studied over the first four days of a week of work, administering a health questionnaire on day 1, measuring their pulmonary function on the morning of day 1 and day 4, and monitoring their personal exposure to SO2 and particulates over the same period. The smelter workers were exposed to an average of 0.374 mg/m3 of respirable particulates, a threefold higher level than the controls, and to 0.67 ppm of sulfur dioxide, a 40-fold greater amount than the controls, but were found to show no excess of chronic respiratory symptoms and did not differ from the controls either in their baseline pulmonary function or in their change from the morning of day 1 to day 4. However, there were several indicators of a healthy worker effect in the smelter worker group.