A Model to Estimate Worker Exposure to Spray Paint Mists

Abstract

Abstract Exposure models traditionally have emphasized the statistical association between process parameters and measured exposures. These empirical-statistical models can identify factors important in controlling exposure, but are difficult to generalize for various reasons. Different modeling techniques may have wider applicability. Known as empirical-conceptual models, they are based on a conceptual analysis that identifies contaminant generation and transport processes leading to the exposure. Dimensional analysis is used to group important process parameters into independent, nondimensional ratios. The relationship among these ratios is then determined from experiment. This research develops an empirical-conceptual model of exposure to mists generated during a spray painting task. Dimensional analysis is used to identify four important dimensionless quantities. Laboratory wind tunnel experiments with a mannequin, flat plate, and spray nozzle provided data to determine the mathematical relationship between these quantities. The model successfully explained the variability in the average breathing zone concentration of the mannequin within measurement uncertainty. Mannequin orientation to the freestream had a significant effect on breathing zone concentrations. A dimensionless quantity consisting of spray nozzle pressure, mannequin height, liquid viscosity, and average freestream velocity determined in which orientation the breathing zone concentration was higher. Differences between the experimental setup and actual spraying tasks may limit application of the model. However, the research indicates good potential for empirical-conceptual models based on dimensional analysis to predict breathing zone concentrations. This should lead to more effective control interventions and reduced exposures.