Relationship of sampling efficiency for manikin-mounted personal samplers to efficiency measurements made independent of manikin

The goal of this study was to determine if measurement of the airflow approaching manikin-mounted personal samplers can be used to predict their sampling efficiency using efficiency measurements made independently of the manikin. The first part of the work involved the determination of the velocity and direction of airflow at specific locations (where personal samplers would be located) around a human-like manikin by using laser-Doppler velocimetry (LDV) at two wind speeds and three orientations of the manikin with respect to the wind. Sampling-efficiency measurements for two personal samplers, the IOM (SKC, Inc., Eighty-Four, PA) and GSP (Strohlein GmbH and Co., Kaarst, Germany) for a 70 μm (mass median diameter) aerosol were made both independently of the manikin for a range of wind speeds and directions and while mounted on the manikin for the wind speeds and directions studied by LDV. The efficiency measurements made independently of the manikin were adjusted by using the local-manikin concentration experienced by the sampler to calculate an approximated efficiency for manikin-mounted personal samplers that experienced a similar wind speed and direction. The approximated efficiency agreed with the measured efficiency of the manikin-mounted samplers when the manikin faced the wind or was at 90° to the wind. Some assumptions were required to obtain agreement when the manikin was at 180° to the wind probably due to the turbulent nature of the flow with the manikin at this angle to the wind. This technique may be useful in simplifying testing procedures and in developing performance criteria for inhalable dust samplers since clearly defined test conditions can be specified.