Measurement of Air Concentrations of Volatile Aerosols in Paint Spray Applications

Abstract

Abstract Spray painting creates aerosols containing droplets and solvent vapors. This work investigated whether traditional vapor sampling measures provide reliable estimates of inhalation exposure during spray painting of automobiles. Measurements of aerosol vapor and droplets were made in spray booths where base coat paint and clear coat finish are applied to automobile bodies. The measurement arrays for both test stand and personal monitoring consisted of charcoal sorbent tubes (CST), diffusion monitors, and glass fiber filters followed by charcoal tubes (F-CST). Xylene and toluene were tested as representative solvents. Measured air concentrations of xylene averaged about 2 ppm at base coat and less than 1 ppm at clear coat applications. Toluene concentrations averaged about 0.1 ppm for both processes. Toluene concentrations and xylene concentrations at clear coat operations as measured by diffusion monitors exceeded those measured by the other samplers. We attribute the apparent increase in sampling rate to membrane damage caused by the solvents. Comparison of F-CST and CST samplers showed that droplets produced during the spraying of both base coat and clear coat operations retain liquid solvent when the droplets reach the breathing zone of workers. The fraction of airborne solvent represented by the droplets will be influenced by both the solvent vapor pressure in the mixture and the original droplet size. For the solvents and processes tested here droplets contained up to 50 percent of airborne solvent. Thus, we recommend the use of prefiltered CSTs for monitoring worker exposure to solvents in spray application processes.