The investigation of the impact of worker locations, orientation, and activity on exposure.
Lee-E; Feigley-C; Khan-J; Tamanna-S; Ahmed-M
American Industrial Hygiene Conference and Exposition, May 21-26, 2005, Anaheim, California. Fairfax VA: American Industrial Hygiene Association, 2005 May; :18
Worker exposure is a complex function of the many factors that affect contaminant transport to the worker's breathing zone. Here the impact of worker position, orientation, and activity was studied in an experimental room. Simulated personal exposures to a tracer gas (propylene) were measured by monitoring the concentration in front of a worker's respirator facepiece. For a stationary worker, simulated exposure was measured at 12 locations within the room, and for four orientations at each location. Simulated exposures of a moving worker were measured along two paths, one close to the source and the other farther from the source. All measurements were made for each of four factorial combinations of air inlet types (wall jet and ceiling diffuser) and air flowrates (5.5 m3/min and 3.3 m3/min). Over the 12 worker locations, the breathing zone concentrations were significantly higher when the worker was facing the source than when not facing the source with ratio ranging from 1.5 to 1.25 (all p-values < 0.05). Exposure downwind of the source. and upwind but close to the source. was higher when the worker was facing the source than when facing away from the source. The TWA exposure of the worker walking along a path near the source was about 1.76 times greater than the exposure of the worker walking along the other path. Also, the exposure of the worker walking along the two paths within the room was significantly higher than the average exposure of the worker standing still at several points along these paths, possibly because worker movement prevents formation of a convective boundary layer found around a stationary worker. These experiments clearly demonstrate the importance of basing exposure estimates on personal sampling when possible rather than area sampling as a result of the impact of worker orientation and movement on breathing zone concentration.
Workers; Work-environment; Air-contamination; Ventilation; Air-flow; Gases; Air-sampling; Air-quality; Exposure-levels; Breathing-zone; Indoor-air-pollution; Indoor-environmental-quality
American Industrial Hygiene Conference and Exposition, May 21-26, 2005, Anaheim, California
University of South Carolina at Columbia, Columbia, South Carolina