The virtual cyclone as a personal respirable sampler

Aerosol exposure via the inhalation route is a primary concern in occupatio nal health. A researcher must perform aerosol size-selective sampling becau se respiratory deposition is dependent on aerosol size. The optimal samplin g instrument is therefore the one that pro,ides the most accurate measureme nt of the atmospheric dust component, thus showing the extent of a health h azard. However, the most commonly used respirable samplers today can only m eet the 50% cut-off point and not the slope of the respirable convention pr escribed by the American Conference of Governmental Industrial Hygienists ( ACGIH), the International Standard Organization (ISO), and the Comite Europ ean de Normalisation (CEN). These conventional cyclones are also found to b e affected by the aerosol deposition and accumulation on the wall of the cy clone body, which leads to a significant decrease in aerosol penetration. I n the present study, a miniature, compact, rugged virtual cyclone, which em ploys a nonimpact particle separation, was developed and constructed to ove rcome the drawbacks of the conventional cyclones. An Aerodynamic Particle Sizer (APS) was used for measuring the particle siz e distributions and the number concentrations upstream and downstream in th e conventional and the virtual cyclones. A square virtual cyclone (21 X 21 X 10 mm, having a curvature radius of 10 mm, outlet width of 1 mm, and inle t width of I mm) was designed to perfectly fit the respirable convention. T his new sampler showed almost no decrease in aerosol penetration due to par ticle loading when operated at a sampling dow rate of 3.3 L/min and aerosol mass concentration of 4.6 mg/m(3) for 3 h. Moreover, this virtual cyclone can be used with a conventional 37 mm cassette through an adapter.