A Multi-Cyclone Sampling Array for the Collection of Size-Segregated Occupational Aerosols

Abstract

In this study a serial multi-cyclone sampling array capable of simultaneously sampling particles of multiple size fractions, from an occupational environment, for use in in vivo and in vitro toxicity studies and physical/chemical characterization, was developed and tested. This 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 nano- and 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/m³. 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 confirmation, scanning electron microscopy was used to collect images of each size fraction. The results presented here, using multiple measurement techniques, show that this multi-cyclone system was able to successfully collect distinct size-segregated particles at sufficient masses to perform toxicological evaluations and physical/chemical characterization.

Keywords:

• crystalline silica
• occupational aerosols
• sampling method
• size segregation

ACKNOWLEDGMENTS

We thank Joe Archer for his expertise in using the Marple chamber and his aid in collecting samples, and we thank Diane Schwegler-Berry for providing the SEM images of the silica crystals. This work was funded by the National Institute for Occupational Safety and Health, Office of Mine Safety and Health Research.