Abstract
Workers in and, in some cases, users of indoor firing ranges continue to receive overexposures to airborne lead levels in spite of efforts to produce smooth and ample ventilation. Studies of firing ranges by researchers for the National Institute for Occupational Safety and Health (NIOSH) and others have shown that only on very infrequent occasions will the ventilation airflow adequately control lead exposures. Some firing ranges use only ventilation to control lead exposures, and these have stimulated a search for the ventilation system elements that will ensure successful control. Substitution of nonlead bullets and primer as a control means has shown some success but has not gained widespread acceptance because of its effects on the accuracy, range, and reliability of firearms. Several approaches leading to adequate ventilation control of lead in indoor firing ranges were investigated. Observations of flow patterns in firing ranges led to an investigation of the firing range air inlet as the primary source of backflow and eddy formation causing elevated lead exposures. Work on a full-scale model firing range shows that backflow can be suppressed in several cases by the use of a double pegboard at the inlet. In addition, a dual inlet with flow alternating between inlets effectively eliminates eddy and wake formation. Flow patterns resulting from various inlet configurations were observed during smoke release studies. Systems that Produced a flow pattern free of backflow over potentially occupied regions of the model firing range, as shown by the smoke release studies, were further investigated by measurements of velocity and turbulence intensity profiles. Further research will involve incorporating these controls in actual firing ranges as confirmation of their adequacy. Smoke release studies also were in the model firing range to determine the effects of the Shooter's booth on airflow at the firing line. Quantitative measurements of relative exposure for a mannequin simulating a shooter were made using smoke release. A smoke concentration measurement was made in the breathing zone by an optical particle detector. Several booth modifications involving slots and.fins were shown to reduce exposures. The shooter's wake was shown to be a fundamental element of backflow exposure paths in these booth studies.