Preliminary investigation of the effects of exposure to multiple health stressors using the physiological strain index

Abstract

Proactive evaluation and management of risks associated with exposure to combinations of occupational health stressors requires information on the impacts of individual stressors, as well as their cumulative and combined impacts. The harsh work environment associated with mining imposes physiological strain on mineworkers. Heart rate (HR) and core body temperature (Tcr) have been shown to be valid and reliable indicators of the physiological strain experienced by humans during physical activity and the physiological strain index (PSI) combines these two parameters. Measurement of the physiological strain caused by individual stressors in a mining environment is confounded by exposure to multiple stressors in various combinations. The research hypothesis was that the occupational health stressors of noise, heat/humidity and physical work would have measurable additive effects on participants’ PSI scores. Eleven participants (three females and eight males) were exposed to noise, heat and physical work in a controlled experiment. A commercially available biotelemetry physiological monitoring system was used to measure HR and Tcr. PSI was determined while participants rested to provide a baseline, for comparison with their respective PSI scores after exposure to individual stressors and various combinations of stressors. The results indicated that noise exposure caused a statistically significant increase in PSI scores. None of the results for exposure to heat alone, physical work alone or the two in combination showed a statistically significant increase in PSI. Simultaneous exposure to all three stressors also increased the PSI but not significantly. Female participants experienced more physiological strain during exposure to noise than males. Male participants experienced more physiological strain from physical work than did females. The PSI appears to be a potentially useful means of measuring total physiological strain experienced during exposure to multiple health stressors but further research involving a greater number of participants is necessary to confirm this conclusion. The comparison of findings in real-time workplace situations with the findings of the study could provide information useful in the management of health risks imposed by exposure to multiple stressors in the workplace.