A Multistage Cyclone Array for the Collection of Size- Segregated Silica Aerosols to Test the Hypothesis That Ultrafine Crystalline Silica Particles Are More Efficient in Their Activation of Macrophages

Occupational exposure to crystalline silica is a well-established occupational hazard. Once in the lung, crystalline silica particles can result in the activation of alveolar macrophages potentially leading to silicosis, a fibrotic lung disease. Because the activation of alveolar macrophages is the beginning step in a complicated inflammatory cascade, it is necessary to define the particle characteristics resulting in this activation. In this study a serial multi-cyclone sampling array (MCSA) capable of simultaneously sampling particles of multiple size fractions, from an occupational environment, was developed and tested and then used to collect sizesegregated crystalline silica particles to determine the effect of the size of crystalline silica particles on the activation of macrophages. The MCSA method is an improvement over current methods used to size-segregate occupational aerosols for characterization, due to its simplicity and its ability to collect sufficient masses of nanoand ultrafine sized particles for analysis. This method was evaluated in a chamber providing a uniform atmosphere of dust concentrations using crystalline silica particles. The multi-cyclone sampling array was used to segregate crystalline silica particles into four size fractions, from a chamber concentration of 10 mg/m. The size distributions of the particles collected at each stage were confirmed, in the air, before and after each cyclone stage. Once collected, the particle size distribution of each size fraction was measured using light scattering techniques, to further confirm the size distributions. As a final