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Assessment Methods for Nanoparticles in the Workplace

Patrick T. O'Shaughnessy
University of Iowa, Iowa City, IA

The primary objectives of this study are to: (1) provide the scientific community and practicing industrial hygienists with verified instruments and methods for accurately accessing airborne levels of nanoparticles; and (2) assess the efficacy of respirator use for controlling nanoparticle exposures. We plan to satisfy these objectives through a combination of laboratory and field-based studies centered on the following specific aims: (1) identify and evaluate methods to measure airborne nanoparticle concentrations; (2) characterize nanoparticles using a complementary suite of techniques to assess their surface and bulk physical and chemical properties, and (3) determine the collection efficiency of commonly-used respirator filters when challenged with nanoparticles.

Our research approach will involve both laboratory and field work. Manufactured nanomaterials covering a range of the types available will be obtained from several sources. We will then systematically compare measurements obtained from a variety of sampling instruments, including a novel passive aerosol monitor, relative to measurements made by transmission electron microscopy (TEM) under controlled laboratory conditions. Field tests will involve the use of the instruments analyzed in the lab to quantify and characterize nanoparticle concentrations in workplaces that manufacture and/or use nanoparticles. This work will also provide the opportunity to refine an aerosol mapping technique we have developed to visualize the temporal and spatial variability of aerosol concentrations in a workplace. Laboratory testing will be conducted to determine the collection efficiency of respirator filters when challenged with a variety of nanoparticle types. We will also analyze the surface properties and chemical composition of a number of nanoparticle types in order to determine whether these qualities can aid in establishing the cause of differences in instrument performance and filtration efficiency when challenged with different nanoparticles as well as to aid in the recognition of unknown nanoparticles encountered in a workplace or in the ambient environment.

This work is an essential first step needed to accurately identify the hazards associated with a new workplace health threat. The expected results from these studies will include a greater understanding of the strengths and limitations of instruments capable of evaluating nanoparticle exposure levels. Our assessment of physical and chemical features of nanoparticles will aid in identifying nanoparticle qualities that affect instrument performance and filtration efficiency. Moreover, this work will result in guidance on the use of respirators to protect against nanoparticle inhalation in the workplace.

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