In 1987, a report was completed studying motionless suspension in harnesses. It was commissioned by OSHA and conducted at the Aerospace Medical Research Laboratory at Wright Patterson Air Force Base in Ohio.
An experiment was conducted using 13 volunteers to evaluate the relative capabilities of three types of fall protection harnesses to provide occupant body support and restraint during post-fall suspension. A series of 39 randomized tests were conducted to evaluate the physiological effects and subjective responses to prolonged, motionless suspension in a body belt, a chest harness, and a full-body harness. Measured physiological parameters included blood pressure, heart rate, and respiratory rate. Subjects were passively suspended in each of the three harness types until subjective tolerance was reached or until symptoms developed which prompted a medical decision to terminate the test. Statistical analysis of the test durations was conducted using the Wilcoxon paired-replicate rank test. Subjective symptoms which prompted test termination were analyzed for the relative occurrence frequency in each harness configuration. Based upon suspension duration and subjective response data, the full-body harness was found to provide better occupant support and restraint for longer periods of prolonged, motionless suspension. The mean suspension time of an individual in a full-body harness was 14.38 minutes with symptoms of light-headedness and nausea prevailing as the primary reasons for test termination. Suspensions conducted in a chest harness lasted an average of 6.08 minutes; light-headedness and strap pressure at the axilla were the most frequent symptoms which terminated a test. Body belt suspensions lasted an average of 1.63 minutes; difficulty breathing along with strap pressure to the abdominal area accounted for the most frequent symptoms prompting test termination.
Authors: Mary Ann Orzech, Mark D. Goodwin, James W. Brinkley, Mark D. Salerno, and John Seaworth.