One means of assessing the hazard risk associated with mine work is to study the severity of injuries that occur during the course of the workday. Of special interest is the accident risk inherent in night work and rotating shiftwork. To better understand this risk, the Bureau of Mines conducted a study of accidents that occurred during a 10-year period in the taconite (iron) mining operations of the U.S. Lake Superior iron ore region. In general, accidents that occurred during the night shift resulted in more days lost per accident, compared with either the day or afternoon shifts. To control for the possibility of different accident types occurring on different shifts, part of this study focused on accidents involving equipment operation. Again, night shift accidents were shown to be significantly more severe than on the other two shifts. These results implicate work performance during night hours as being relatively impaired, perhaps due to lowered states of psychophysiological arousal, coupled with the handicap of operating in a darkened environment.
THE LAKE SUPERIOR IRON-ORE MINES, AND THEIR INFLUENCE UPON THE PRODUCTION OF IRON AND STEEL. (INCLUDING APPENDIXES AND PLATES AT BACK OF VOLUME).