Subjective health scores were obtained from 104 workers who were about to start work in shifts in a newly set-up wire mill. These workers were re-examined six months later, at which lime a decrease in their health scores was evident. Four years and four months after they started working in the new plant, 95 workers out of the original 104 were studied a third time. Subjective health had further decreased in the 64 subjects who were still working in the plant, but in the 31 subjects who had left it had stabilised approximately al the level recorded after six months.