Breathing zone concentration variations in the reinforced plastic industry; field measurements in a boat manufacturing plant.
Breathing zone samples are used to estimate worker exposure to airborne contaminants by collecting air from a vaguely defined zone surrounding the head. This zone is considered to have an airborne chemical concentration equivalent to the concentration breathed by the worker. It has been generally assumed that vapor is uniformly mixed in the breathing zone; therefore, samplers are placed on either lapel or on the chest of the worker. An extensive field investigation in a boat manufacturing plant was conducted where styrene air concentrations were measured by mounting four 3M one-stage diffusion samplers around the worker's breathing zone. Two job classes were studied: the spray gun operators and the rolling and tucking operators. Styrene air concentrations detected at the nose were significantly different than those concentrations detected at the other three locations and represented 90 percent, 84 percent, and 76 percent of the left lapel, right lapel, and chest samplers, respectively. This research revealed that the chest sampler provides a consistent relationship to the concentrations measured at the nose for a given job category. Additionally, this research identified the possible factors which could contribute to breathing zone concentration variations.