ABSTRACT. Three particle size fractions of airborne dust are de® ned in European and U.S. standards for health-related dust measurements at the workplace: the respirable, the thoracic, and the inhalable fraction. We developed a novel instrument for personal, time-resolved concentration monitoring and s ampling of these three fractions. The instrument combines inertial classi® cation, ® lter sampling, and photometric aerosol detection. It consists of a two-stage virtual imp actor ( ) cut-off diameters of 4 and 10 m m , three ® lters, and three light scattering photometers. The virtual impactor serves as a particle size classi® er and a coarse particle concentrator. This enrichment compensates for the decreasing particle mass-based photometric sensitivity with increasing particle diameter. The optical sensors are calibrated in-situ via the mass concentrations obtained gravimetrically from the ® lter samples. The device operates at a¯ow rate of 3.1 l r r r r r min . There is strong agreement between the experimentally determined particle size-dependent collection ef® ciencies and the de® nition curves of the corresponding dust fractions. The size dependence of the sensitivity of the inertial concentrator and photometric detection units follow the de® nition curves qualitatively. Exposure data were obtained for different workplace environmen ts ch aracterized by temporally and spatially highly¯uctuating concentrations. The ® eld measurements have shown that the instrument is practicable under rough industrial conditions and that it enables a more comprehensive and more realistic characterization of the individual exposure of workers to health-endangering dusts th an was previously possible.

The Respicon has been introduced as a sampler for health related measurements of airborne contaminants at workplaces. The instrument is aimed at simultaneous collection of three health related aerosol fractions: (a) the coarser inhalable fraction, defining the aerosol fraction that may enter the nose and mouth during breathing; (b) the intermediate thoracic fraction, defining the fraction that may penetrate beyond the larynx and so reach the lung; and (c) the finer respirable fraction, defining the fraction that may penetrate to gas exchange region of the lung. The instrument has a number of features attractive to occupational hygienists: in addition to providing the three aerosol fractions simultaneously, it is light and compact enough to be used as a personal sampler. yet can be a tripod mounted for area sampling, it can provide samples not only for gravimetric analysis but also microscopic and chemical analyses; and it is also available in a photometric direct-reading version. The instrument has previously been evaluated as an area sampler and, in this mode of operation, has shown reasonable accuracy in collecting respirable, thoracic and inhalable particles, the latter up to particle diameters of ca. 80 microm. Except for some scattered unpublished data there exist no systematic investigations in the Respicon's performance when used as a personal sampler in the industrial environment. In this paper, we will report on a study of side by side comparison of the Respicon with the IOM inhalable sampler, regarded as a reference instrument for the inhalable fraction. The main study was performed at six different workplaces in a nickel refinery. Statistical analysis of the gravimetrically-determined concentration data reveals consistently lower aerosol exposure values for the Respicon as compared to the IOM sampler. The data for the nickel workplaces are compared with findings from other studies. The results are interpreted in the light of the overall results and the possibility of introducing a correction factor is discussed.

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A computer-controlled spray-generating and spray-exposure unit called RHINOCON was designed and constructed to offer the possibility of depositing, for example, environmental or pharmaceutical aerosols at the air/liquid interface under realistic exposure conditions. Here, isolated human respiratory cells are chosen to simulate, as far as possible, the in vivo situation. The exposure unit is equipped to hold up to 6 commercially available pump-spray dispensers, which are prepared mechanically for exposure as described in the manufacturer's users' guide. A transwell insert containing the cells is placed opposite each dispenser in a special plate head rst. After starting the program, the spray dispensers are shaken and actuated automatically. The spray is released into an air ow passing over the cells, where the spray droplets are deposited due to their inertia. After exposure, the inserts can easily be removed and processed to measure a variety of cell toxicity parameters, such as cell viability or cell metabolism. Validation of the experimental setup was performed in an initial set of experiments: (1) by determination of the deposited amount of nebulized test substance on transwell membranes, and (2) by investigation of the cellular reactions of a human respiratory epithelial cell line (HFBE 21) exposed to nebulized hydrogen peroxide or to standard medium as a reference control.Keywords aer os ol, a ir/ liqu id in t er fa ce, expos ur e syst em , h u m a n r espirat or y cells, in vit r o, ph ar m a ceu t ica l a er osol pr od u ct s N owa d a ys, in vit r o st u dies on expla n t s, or isola t ed h u m a n cells, offer a u n iqu e ch a n ce t o st u dy su bs ta n ce effect s dir ectly on h u m a n m a ter ia l wit h ou t u sin g a n im a l st u dies or h u m a n volu n t eer s. N ever t h eless, u n t il n ow, in vest iga t ion s of t h e biologica l effect s in du ced by com plex m ixt u r es on cells of a pr im a r y con ta ct or ga n , lik e th e r esp ir a tor y t r a ct , h a ve been lim it ed. In t h is ca se, it is beca u se t h e subst a n ces a r e, for t h e m ost p a r t ,

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