Autocorrelation of Interday Exposures at an Automobile Assembly Plant

Abstract

This article presents an analysis of interday autocorrelation in the exposure time series of workers in an automobile assembly plant. In all, serial 8-hour time-weighted average exposures for six workers, two each at three separate processes, were monitored for periods ranging from 20 to 110 consecutive days. Autocorrelation was assessed in each case. In general the results support the conclusions of previous investigations, in that relatively little autocorrelation was observed. However, uncertainties regarding the stationarity of the time series over the period of interest highlight potential difficulties in autocorrelation analysis. Particularly, nonrandom events in a plant, such as ventilation and process changes and extended down times, should be considered in any autocorrelation analysis inasmuch as these factors may affect the distributional parameters as well as the stationarity of the time series. In the workplace under study these nonrandom events appear to be more important in the overall asses...