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Development of a High-Volume Concentrated Ambient Particles System (CAPS) for Human and Animal Inhalation Toxicological Studies

A two-stage, high-volume, ambient particle concentrator was developed and characterized. This versatile system, depending on its operational parameters, can be used to fractionate and concentrate particles in three size ranges (PM 10-2.5, PM 10-1, PM 2.5-1) . The performance of this concentrated ambient particle system (CAPS), as well as its individual virtual impaction stages, was investigated as a function of several parameters, including minor-to-total flow ratios and acceleration nozzle Reynolds number. During these laboratory tests, performance parameters such as concentration enrichment factor (CF), particle losses, collection efficiency curves, cutpoint, and pressure drop were measured. The main objective of these investigations was to optimize the ability of the system to concentrate ambient PM 2.5-10 and PM 1-10 particles. PM 2.5-10 particles were concentrated by a factor of 70 to 150. The flow rate of the concentrated aerosol can range between 12.5 and 50 LPM (L/min). Other features of the system include relatively low-pressure drops in the major and minor flows, low particle losses, and a compact design. Performance evaluation of the system also confirmed that separation and concentration of the PM 2.5-10 particles occurred without any significant distortion of the size distribution, during the concentration process. Similar results were obtained for the PM 1-10 size range. For this size range, concentration enrichment was 70 times, and again, no particle size distribution distortion was observed. The overall performance of this versatile system makes it suitable for inhalation toxicological studies.