Nanoparticle Emission Assessment Technique (NEAT) for the Identification and Measurement of Potential Inhalation Exposure to Engineered Nanomaterials—Part A

Abstract

There are currently no exposure limits specific to engineered nanomaterial nor any national or international consensus standards on measurement techniques for nanomaterials in the workplace. However, facilities engaged in the production and use of engineered nanomaterials have expressed an interest in learning whether the potential for worker exposure exists. To assist with answering this question, the National Institute for Occupational Safety and Health established a nanotechnology field research team whose primary goal was to visit facilities and evaluate the potential for release of nanomaterials and worker exposure. The team identified numerous techniques to measure airborne nanomaterials with respect to particle size, mass, surface area, number concentration, and composition. However, some of these techniques lack specificity and field portability and are difficult to use and expensive when applied to routine exposure assessment. This article describes the nanoparticle emission assessment technique (NEAT) that uses a combination of measurement techniques and instruments to assess potential inhalation exposures in facilities that handle or produce engineered nanomaterials. The NEAT utilizes portable direct-reading instrumentation supplemented by a pair of filter-based air samples (source-specific and personal breathing zone). The use of the filter-based samples are crucial for identification purposes because particle counters are generally insensitive to particle source or composition and make it difficult to differentiate between incidental and process-related nanomaterials using number concentration alone. Results from using the NEAT at 12 facilities are presented in the companion article (Part B) in this issue.

Keywords:

• concentration
• emissions
• nanoparticle
• nanotechnology
• occupational exposure
• particle number
• sampling

ACKNOWLEDGEMENT

The authors wish to gratefully acknowledge the support of Paul A. Schulte, manager of the NIOSH nanotechnology cross-sector program, and John Howard, director of NIOSH. Special thanks go to M. Eileen Birch, Keith Crouch, Brian Curwin, Kevin H. Dunn, Douglas Evans, Mark Hoover, Bob-Ki Ku, Aleksandr Stefaniak, and Paul A. Baron for their consultative expertise.