Statistical evaluation of occupational noise exposure

Assessment of the risk involved in occupational noise exposure (LEP,d) is significantly affected by assumptions and uncertainties in setting true exposure conditions meaning that the calculation according to the European legislation might not be fully representative. The paper describes a probabilistic model to evaluate occupational noise exposure and calculate the confidence interval for LEP,d. This confidence interval is defined in function of the number of samples of both exposure time and equivalent noise level that must be taken in different areas of the work environment or for different operator tasks. The model determines the minimum number and the type of samples to obtain a confidence interval for LEP,d which falls with the given level of precision entirely into the classes defined by 86/188/CEE Directive (and following 2003/10/CE Directive). Finally, the model has been applied (by means of a software tool implementing the model and developed by the authors) to a newspaper rotary press plant, where production is supervised by a team of workers that access the various parts of the plant (3 vertical levels) for regulation and/or maintenance.