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Modeling a worker's exposure from a hand-held source in a uniform freestream.
Am Ind Hyg Assoc J 1991 Nov; 52(11):458-463
A simple conceptual model was developed to test assumptions concerning the proper design of local exhaust ventilation systems intended to control the concentration of toxic airborne contaminants in a worker's breathing zone. This current study revised the earlier model based on experimental results. This revised model was validated using a tracer gas method in a wind tunnel. Results suggest the growing importance of turbulent diffusion and enhanced mass transport with increasing Reynolds number. The inverse proportionality of the breathing zone concentration to the freestream velocity and the dimensions of a worker suggest that the exposure for a bigger person may be lower than that for a smaller person. Increasing the freestream velocity will not always be a cost effective measure to control worker exposure. The authors caution that care needs be taken when extrapolating the results to real life situations as the stationary mannequin, the passive contaminant source, and the uniform freestream used in this study are not representative of many industrial situations.
NIOSH-Publication; NIOSH-Grant; Control-technology; Occupational-exposure; Mathematical-models; Exhaust-ventilation; Air-flow; Air-contamination; Ventilation-systems; Toxic-gases
Environmental Sciences & Engr University of North Carolina Rosenau Hall 201H Chapel Hill, NC 27514
Issue of Publication
American Industrial Hygiene Association Journal
University of North Carolina Chapel Hill, Chapel Hill, North Carolina
Page last reviewed: March 11, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division