Inhalation exposures during cleaning activities

Abstract

Studies show that the use of cleaning products is related to adverse respiratory health effects ranging from irritation to asthma. Yet exposure to these chemicals is poorly understood. This dissertation summarizes the current state of knowledge of inhalation exposure to toxic chemicals in consumer cleaning products. An improved two-zone model that treats personal air space as distinct from bulk room air is presented. The model accounts for air exchange between the two zones, dynamic source characteristics (i.e., the time-varying liquid concentrations and emission rates of pollutants within a mixture), and the characteristics of chemical use (e.g., how frequently a cleaning chemical is applied to a new area). To assess exposure to cleaning products and validate the improved two-zone model twenty-three experiments, encompassing six cleaning scenarios, were completed in an environmentally-controlled chamber with a thermal mannequin. Then, the model was used to predict exposure for four hypothetical cleaning scenarios and compared against other models. The model's applicability is restricted by limited data available for parameterization. At low air exchange rates gas-phase experimental results show concentrations in the breathing-zone of the mannequin exceeded concentrations predicted by the well-mixed model by factors up to 2.1. Breathing-zone concentrations also exceed those measured at centralized room monitors by factors up to 6.1. Thus, studies that use the centralized room monitors or the well-mixed model as a surrogate for breathing-zone concentrations could potentially underpredict exposure at low air exchange rates. The two-zone model provides the best prediction of exposure to cleaning tasks, at low air exchange rates. The next best model is the well-mixed model with an exponentially decreasing emission rate, followed by the well-mixed model with a constant emission rate. At high air exchange rates the well-mixed assumption appears to be valid. The inner-zonal volume and inter-zonal air exchange were independent of fresh air ventilation rate. But both were dependant on the mannequin's body position, with standing having the highest inner-zonal volume and lowest intra-zonal air exchange rate of the three body positions investigates (standing, bent over 45°, and hands and knees).