NORA Manufacturing Sector Strategic Goals
927ZBCQ - Real-time Instrument for Nanoaerosol Exposure Measurement
Principal Investigator (PI)
Primary Goal Addressed
Secondary Goal Addressed
Attributed to Manufacturing
Growing evidence suggests that toxicity of nanoparticles may be closely associated with particle size, number, and surface area rather than mass. To address increasing concerns over the potential occupational health risks of nanomaterials, development of new personal instruments to simultaneously measure workplace exposure to multiple metrics has been recommended. This project fills this void through development of an instrument to measure personal exposure to number, surface area, and mass concentration of nanoaerosols. New Personal Nanoaerosol Sizer will be designed and developed to measure real-time, number-weighted particle size distributions of nanoaerosols in the workplace. Laboratory and field research will be designed to test the instrument. Real-time capability of the Personal Nanoaerosol Sizer to monitor multiple dose metrics will substantially help to reduce and control exposure to engineered nanomaterials in the workplace.
Growing toxicological evidence suggests that for aerosol particles smaller than about 100 nm in diameter, the toxicity of particles is closely associated with their size and number or surface-area, rather than their mass. Following such concerns, most researchers agree that for airborne exposures there is still insufficient evidence to preferentially choose one exposure metric over the other, and that where there is uncertainty multiple metrics should be used. This proposal is based on the hypothesis that the simultaneous measurement of exposure to number, surface area, and mass concentration can be obtained if the particle size distribution of the aerosol is known.
The objective of this proposal is to support development of a simple, low-cost, miniature personal device that can continuously measure and record near-real-time, simultaneous personal exposure to number, surface area, and mass concentration of engineered nanoparticle- and ultrafine- aerosols in the workplace. Specifically, the proposed work involves development of a personal device to measure near-real-time particle size distribution of workplace nanoaerosols using electrical mobility based size classification, followed by detection using an electrical particle sensor. The instrument, referred to as Personal Nanoaerosol Sizer, consists of three components—an electrical charger, a mobility classifier, and an electrical sensor. The aerosol particles first enter the unipolar charger where they are electrically charged, following which the particles undergo size classification in the mobility classifier according to their mobility size. The size classified aerosol particles are subsequently detected by the particle sensor. Research will be undertaken to design, construct, and calibrate all the three components. Hardware accessories and software systems will also be developed to support continuous operation of the instrument in the field. Research will be undertaken to thoroughly characterize the personal sampler in the laboratory to obtain its measurement accuracy, precision, dynamic range, and other performance specifications. Field research will be designed to test and evaluate the performance of the instrument in representative workplaces. Guidelines will be developed for effective use of the PNS for monitoring ultrafine and engineered nanoparticle aerosols in the workplace.
The research on this four-year project will be conducted in collaboration with leading Investigators from NIOSH, Washington University, NanoEngineering Corp., TSI Inc., and Brookhaven National Laboratory, who have strong interdisciplinary backgrounds in aerosol instrumentation and workplace exposure assessment. The project involves partnerships with two instrumentation companies—TSI Inc., a world leader in aerosol instrumentation, and NanoEngineering Corp., a company involved in research and development, and commercialization of nanoparticle instrumentation. These collaborations will provide an effective platform for commercializing the instrument through technology transfer.
The work under this project is expected to produce 8-10 peer-reviewed publications and two patents. The main outcome of this project will be a low-cost personal aerosol instrument for workplace nanoaerosol exposure monitoring. In a broader epidemiological context, this personal aerosol instrument will enable recording of exposure against aerosol number, surface area and mass concentration simultaneously in the long term to provide a historic database that can be re-assessed in light of new knowledge and new exposure monitoring paradigms. This project directly supports NIOSH's mission to provide global leadership in preventing work-related illness. The personal sampler developed through this project will also be of significant interests to many other federal agencies for applications involving personal nanoparticulate exposure, early smoke detection, distributed measurements for air pollution epidemiology, environmental health, and indoor air quality.
The objective of this project is to develop a simple, low-cost, miniature personal device that can continuously measure and record near-real-time, simultaneous personal exposure to number, surface area, and mass concentration of airborne engineered nanoparticles and ultrafine aerosols in the workplace.
Specifically, the proposed work involves development of a personal instrument to measure near-real-time, number-weighted particle size distribution (PSD) of workplace nanoaerosols using electric mobility based size classification, followed by their detection using an electrical sensor. The sampler, referred to as Personal Nanoaerosol Sizer (PNS), consists of three miniature components—a unipolar electrical charger, a mobility classifier, and an electrical particle sensor.
The specific aims of this project are to:
1. Design, construct, and characterize a compact or miniature mobility classifier to facilitate classification of mobility size of aerosol particles.
2. Design, construct, and characterize a miniature unipolar aerosol charger to impart electrical charge to the aerosol particles as required for successful operation of the mobility classifier.
3. Design, construct, and characterize a miniature Faraday cup electrometer (FCE) particle sensor to detect particles classified by the mobility classifier.
4. Integrate all three PNS components above and develop supporting hardware and software for continuous field operation. Perform thorough laboratory testing of PNS.
5. Conduct field investigations to evaluate the performance of PNS in representative workplaces, and provide guidelines for its routine workplace use.
A conservative estimate shows that over 2 million people in the U.S. workforce are exposed to engineered nanoparticles and ultrafine particles (<100 nm in diameter) on a regular basis. In addition, emergence of nanotechnology is expected to add about 2 million workers to the global workforce in the next 15 years to support the nanotechnology industry. While novel technologies are being rapidly developed to produce nanostructured materials to possess unique physico-chemical functionality, the same functional characteristics may have undesirable effects on human health. This has led to increasing concerns over risk of occupational exposure to airborne functional nanomaterials.
The pulmonary toxicity of ultrafine particles has been well studied for over a decade and the evidence indicates that these particles cause ill health when they are produced in large quantities—this further provides a context to assess the potential hazard of engineered nanomaterials. Increasing evidence also suggests that the toxicity of nanoparticles does not follow conventional models based on mass and bulk chemical composition, but rather is associated with particle number, size, surface area and chemistry. In order to link the hazard posed by the nanomaterials to their exposure levels, researchers in academia, government, and industry have recommended development of instrumentation for workplace nanoaerosol characterization. The proposed project aims to develop a personal device to measure exposure to number, surface area, and mass concentration of airborne nano- and ultrafine- particles.
The proposed work falls primarily within the NIOSH Cross-sector on Exposure Assessment, and NIOSH Cross-sector Program on Respiratory Diseases. This project is directly aligned with Intermediate Goals 1.3 (09PPEXAIG1.3) and 2.11 (09PPEXAIG2.11) of Exposure Assessment, and address the critical Activity/Output 2.11.1 (09PPEXAAOG2.11.1), and 2.11.2 (09PPEXAAOG2.11.2) therein. The project also directly addresses Intermediate Goal 5.1 (09PPRDRIG5.2) of the Respiratory Disease cross sector, and Activity/Output Goal 5.2.1 (09PPRDRAOG5.2.1)