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Nanoparticle Occupational Safety and Health Consortium: Aerosol Nanoparticle Behavior and Barrier Efficiency of Filter Media to Engineered Aerosol Nanoparticles

Michele L. Ostraat1, Keith A. Swain2, James J. Krajewski1, and Robert J. Small1. (1) DuPont Engineering Research and Technology, Wilmington, DE 19880-0304, (2) DuPont Central Research and Development, Wilmington, DE 19880-0304

The Nanoparticle Occupational Safety and Health (NOSH) consortium of international industrial, academic, government and non-governmental organizations has focused research since the beginning of 2006 upon obtaining information on occupational safety and health associated with nanoparticles and workplace exposure monitoring and protocols. The three main technical goals of the consortium are 1) the development of a method to generate a well-characterized aerosol of solid nanoparticles and to measure aerosol behavior as a function of time; 2) the development of an air sampling method that can be used on a day-to-day basis in laboratories and manufacturing settings; and 3) the ability to measure barrier efficiency of filter media with respect to specific engineered aerosol nanoparticles. Since one stated objective of the NOSH consortium is the wide dissemination of all findings, including nanoparticle synthesis methods, behavior of aerosol nanoparticles as a function of time, and barrier efficiency of commercially available filter media to aerosol nanoparticles, this talk will serve as one method to present data and findings from the consortium.

This consortium continues work towards developing knowledge of workplace exposure monitoring capabilities and strategies through the design and development of portable aerosol monitoring instrumentation for conducting assessments of worker exposure to airborne engineered nanoparticles. Additionally the consortium continues to conduct studies to obtain knowledge of the barrier performance characteristics of commercially available filter media to aerosol nanoparticles. To accomplish these objectives, multiple aerosol synthesis and characterization systems have been designed and optimized to generate well-characterized aerosol nanoparticles of various chemistries in the 3 100 nm size range. These aerosol nanoparticles are transported to one of three enclosed aerosol test chambers in which the concentration and particle size distribution of the incoming aerosol nanoparticles are controlled to examine aerosol behavior as a function of time, including rate of dispersion, aggregation, and particle loss for both charged and uncharged aerosol nanoparticles. These well-controlled and well-characterized aerosol nanoparticle studies form the basis for the development of a portable aerosol monitoring instrument which will be field tested in a wide variety of workplace environments.

Engineering controls, respiratory protective devices and protective clothing fabrics are generally considered to provide adequate protection for exposures to fine-sized particulates. However, prior to the consortium inception, the available methodologies utilized in industrial hygiene practices to measure particle exposures were typically not sufficiently sensitive to measure occupational or ambient nanoparticle aerosol concentrations, whether in terms of particle mass, particle numbers, or surface area. Through this effort, the consortium has developed the instrumentation and protocols required to assess the barrier effectiveness of filter media to charged and uncharged aerosol nanoparticles as a function of particle chemistry, particle size distributions, and number concentration. The consortium continues to focus on identifying appropriate filter media that can be used as effective barriers for aerosol nanoparticles and on determining specifications for using those filter media given a set of known properties about a specific nanoparticle aerosol.