[Effect of cross current due to worker's arm movement on local exhaust ventilation hood].

The effect of cross drafts caused by a worker's arm movements on the capture efficiency of a local exhaust ventilation hood was examined in a laboratory. The performance of the local exhaust hoods (rectangular type and slot type) and the transportation of gaseous contaminants from an emission source to the breathing zone were studied by means of the tracer gas method. Acetone vapor was used as a tracer gas. The worker's arm movement was simulated by a dummy worker and a moving forearm model. The results suggest that a worker's arm movements disturb the exhaustion efficiency and may lead to exposure or leakage from a hood according to exhaust velocity.