Field Evaluation of an Empirical—Conceptual Exposure Model

Abstract

Empirical-conceptual models relate exposure to various process parameters responsible for the generation and transport of airborne contaminants. If the model includes all process parameters important to defining the exposure, it has the potential for a priori exposure prediction. This research tested the ability of an empirical-conceptual model of a spray painting task to predict worker exposures in the field. The model relates paint mist concentrations to spray booth ventilation rates and other process parameters, including spray gun nozzle pressure, paint viscosity, mist generation rates, and worker orientation to the booth freestream. Eight workers in a paint shop were sampled over a 5-week period. A total of 55 tasks were sampled; 40 percent of the measured task exposures are within the estimated experimental error of the model prediction and 71 percent are within a factor of three. Excluding tasks that either did not fit the model assumptions well or where a sampling error may have occurred increases the percentage to 84 percent within a factor of three. Four of the eight worker mean exposures are within one standard error of the model prediction. These positive results indicate that empirical-conceptual models can predict exposure and also aid in the design and economic optimization of engineering controls.