THE USE OF MEASUREMENTS AND TWO-ZONE MODEL TO ESTIMATE OCCUPATIONAL NANOPARTICLE EXPOSURE DURING SPRAY APPLICATION

The rapid growth and frequent application of nanotechnology brought concerns for the exposure of nanoparticles to the users of nanoparticle-containing products and for surrounding people. This study used field measured personal breathing zone data to estimate the generation rate of nanoparticles during spray application and predicted the area concentrations over time using the Two-Zone model (Near-field / Far-field model), with the aid of IHMod 2.0, Oracle Crystal Ball and their embedded Monte Carlo simulations. This study determined the generation rate and estimated the far-field concentration in a scenario with spray application for 15 minutes and 15 minutes of settling time. Oracle Crystal Ball generates sensitivity charts during Monte Carlo simulation to evaluate the strength of variables in influencing the simulation result. During the study, the sensitivity charts generated suggested that the near-field concentration measured, and the radius of the near-field sphere were important in determining the far-field concentration. It is not recommended to use this model in actual practice at this point of time as the quality of prediction has not been tested. Future onsite measurements need to be conducted to determine the far-field concentration with considerations of variability, uncertainty and the values of the distance between the operator and the source, and the random air speed, thereby validating this model through comparison