ABSTRACT
It is now well accepted that workers' exposures to airborne chemicals vary greatly over time. This variability obviously complicates the process of assessing exposures; 1 for example, it no longer appears appropriate for the industrial hygienist to base decisions concerning a working lifetime upon only a few measured air concentrations. Rather it seems that a premium is often placed upon gathering sufficient relevant data to characterize exposure distributions received over time. The parameters of these distributions can then be used in a variety of useful ways to quantify, classify, and limit exposures.
