Development of a new exposure monitoring system considering pulmonary ventilation (DEM 1)

Exposure evaluation is an essential facet in the assessment of the risks of exposure to toxic materials in the workplace. Presently, samples from the breathing atmosphere are measured in order to determine the level of individual exposure to toxic substances. This method, however, does not take into account the level of physical exertion during exposure. Physical activity is known to increase pulmonary ventilation by up to 10 times that of the level at rest. Thus, measurement of pulmonary ventilation, as well as the concentration of a toxic material in the air would provide valuable data in evaluating exposure. We have developed a device that measures and records the concentration of a toxic material in the air and pulmonary ventilation as predicted by heart rate both simultaneously and continuously. In this system, real time pulmonary ventilation is predicted from heart rate by using a regression equation that was obtained from the results of our study. The percentage error of predicted pulmonary ventilation at each heart rate is within 30%. The present study assessed the feasibility of the use of heart rate as the predictor of pulmonary ventilation. Our new exposure monitoring system is the first practical device that monitors the level of exposure dependent upon pulmonary ventilation and will be useful in the reevaluation of threshold limit values (TLV's) and in working management.