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High flow rate respirable size selective samplers, GK4.126 and FSP10 cyclones, were calibrated for thoracic-size selective sampling in two different laboratories. The National Institute for Occupational Safety and Health (NIOSH) utilized monodisperse ammonium fluorescein particles and scanning electron microscopy to determine the aerodynamic particle size of the monodisperse aerosol. Fluorescein intensity was measured to determine sampling efficiencies of the cyclones. The Health Safety and Laboratory (HSL) utilized a real time particle sizing instrument (Aerodynamic Particle Sizer) and poly-disperse glass sphere particles and particle size distributions between the cyclone and reference sampler were compared. Sampling efficiency of the cyclones were compared to the thoracic convention defined by the American Conference of Governmental Industrial Hygienists (ACGIH)/Comité Européen de Normalisation (CEN)/International Standards Organization (ISO). The GK4.126 cyclone showed minimum bias compared to the thoracic convention at flow rates of 3.5 l min−1 (NIOSH) and 2.7–3.3 l min−1 (HSL) and the difference may be from the use of different test systems. In order to collect the most dust and reduce the limit of detection, HSL suggested using the upper end in range (3.3 l min−1). A flow rate of 3.4 l min−1 would be a reasonable compromise, pending confirmation in other laboratories. The FSP10 cyclone showed minimum bias at the flow rate of 4.0 l min−1 in the NIOSH laboratory test. The high flow rate thoracic-size selective samplers might be used for higher sample mass collection in order to meet analytical limits of quantification.

Abstract
Handling of hazardous materials in occupational settings can lead to worker exposure by inhalation. Dustiness testing, such as the EN 15051-2 rotating drum tester, provides suppliers and users of bulk materials with information on the potential for dust emission from hazardous substances when handled or processed in the workplace. This tester agitates powder samples in a rotating drum and the resulting dust is collected and sized by drawing it through two reticulated metal foams. Two approaches were used to evaluate the performance of the metal foams. Firstly, the performance of the metal foams was measured in a calm air chamber using a polydisperse aerosol of glass particles and assessed against the EN 481 respirable convention. Secondly, the performance of the metal foam for the respirable fraction was compared using the rotating drum dustiness test, with that of a cyclone set-up, using four polydisperse glass powders of different size distribution and dustiness potential. In general, for the respirable fraction, the tests demonstrated a conservative oversampling by the current EN 15051-2 metal foam set-up in comparison with the EN 481 convention. This study also showed the importance of sealing the circumference of the metal foams when testing highly dusty powders. A direct comparison of the respirable dustiness fraction measured by the current EN 15051-2 metal foams set-up and by a cyclone set-up, showed broad agreement. However, the cyclone gave lower values except where foam clogging occurred. The research also highlighted suggested improvements to the EN 15051-2 standard.
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