University of Iowa Iowa Research Online Theses and Dissertations Fall 2010 Use of direct-reading instruments for measuring airborne nanoparticles in the workplace Donna Jean Holzer Vosburgh University of Iowa Copyright 2010 Donna Jean Holzer Vosburgh This dissertation is available at Iowa Research Online: https://ir.uiowa.edu/etd/901 Recommended Citation Vosburgh, Donna Jean Holzer. "Use of direct-reading instruments for measuring airborne nanoparticles in the workplace." PhD (Doctor of Philosophy) thesis, University of Iowa, 2010. https://doi.org/10.17077/etd.ypvmbm2u Follow this and additional works at:https://ir.uiowa.edu/etd Part of theOccupational Health and Industrial Hygiene Commons USE OF DIRECT-READING INSTRUMENTS FOR MEASURING AIRBORNE NANOPARTICLES IN THE WORKPLACE by Donna Jean Holzer Vosburgh An Abstract Of a thesis submitted in partial fulfillment of the requirements for the Doctor of Philosophy degree in Occupational and Environmental Health (Industrial Hygiene) in the Graduate College of The University of Iowa December 2010 Thesis Supervisor: Associate Professor Thomas M. Peters 1 ABSTRACT This work strived to increase knowledge of assessing airborne nanoparticles in the workplace by characterizing nanoparticle concentrations in a workplace using direct- reading instruments, evaluating a DC2000CE diffusion charger, and the creation of a personal diffusion battery (pDB). Direct-reading instruments were used with aerosol mapping and task monitoring to evaluate airborne nanoparticle concentrations in an apparel company that produces waterproof jackets composed of polytetrafluoroethylene membrane laminated fabric. Jacket production required that sewn seams be sealed with waterproof tape applied with hot air (600°C). Particle number concentrations were greater in the sewing and sealing areas than the office area while respirable mass was negligible throughout the facility. The breathing zone particle number concentrations of the workers who sealed the sewn seams were highly variable and significantly greater when sealing seams than when conducting other tasks (p<0.0001). The effectiveness of the canopy hoods used to ventilate sealing operations was poor. These measurements support the idea that work places where hot processes are conducted may have substantially greater concentrations of airborne nanoparticles than background measurements even with control measures in place. Laboratory tests were conducted to evaluate a commercially available diffusion charger, the DC2000CE, that measures nanoparticle surface area concentration. The surface area concentrations of unimodal and multimodal polydispersed aerosols measured by the DC2000CE were less than the surface area concentrations measured by the reference instruments. The differences in results were attributed to a difference of measuring active versus geometric surface area concentration and the design of the DC2000CE. The maximum measurable active surface area concentration (2,500 mm2 m-3) was found to be greater than the manufacturer stated maximum (1000 mm2 m-3). Moving or vibrating a DC2000CE while taking measurements can cause 2 the appearance of increased surface area concentration results. The DC2000CE has limitations that must be acknowledged when using the DC2000CE to measure airborne nanoparticle surface area concentrations in a workplace. A four stage pDB (3.2 kg) composed of a screen-type diffusion battery, solenoid valve system, and an electronic controller was developed. The pDB was combined with a CPC and a data inversion was created that could be used to solve for the number median diameter, geometric standard deviation, and particle number concentration of a unimodal distribution. The pDB+CPC with inversion was evaluated using unimodal propylene torch exhaust and incense exhaust. For particle number concentration of particles with diameters less than 100 nm, the pDB+CPC with inversion results were between 86% to 109% of reference instrument results when the inversion did not solve to an inversion constraint and between 6% to 198% for results that solved to an inversion constraint. When coupled with a direct-reading instrument, the pDB with an inversion was able to measure the size distribution of particles with a NMD smaller than 286 nm. Abstract Approved: ______________________________________________________ Thesis Supervisor ___________________________________________________ Title and Department ___________________________________________________ Date USE OF DIRECT-READING INSTRUMENTS FOR MEASURING AIRBORNE NANOPARTICLES IN THE WORKPLACE by Donna Jean Holzer Vosburgh A thesis submitted in partial fulfillment of the requirements for the Doctor of Philosophy degree in Occupational and Environmental Health (Industrial Hygiene) in the Graduate College of The University of Iowa December 2010 Thesis Supervisor: Associate Professor Thomas M. Peters Graduate College The University of Iowa Iowa City, Iowa CERTIFICATE OF APPROVAL _______________________ PH.D. THESIS _______________ This is to certify that the Ph.D. thesis of Donna Jean Holzer Vosburgh has been approved by the Examining Committee for the thesis requirement for the Doctor of Philosophy degree in Occupational and Environmental Health (Industrial Hygiene) at the December 2010 graduation. Thesis Committee: ___________________________________ Thomas M. Peters, Thesis Supervisor ___________________________________ T. Renee Anthony ___________________________________ Patrick O'Shaughnessy ___________________________________ Jacob Oleson ___________________________________ Wayne Sanderson To David, thank you for your unwavering faith 2 ii It’s only the difference between looking and seeing. Look long enough and if you’re doing it right you get to see. Nicholas Evans The Horse Whisperer 3 iii ACKNOWLEDGMENTS I would like to offer my sincere thanks my advisor, Tom Peters, for his guidance and advice. Without his patience, eagerness to share his knowledge, and interest in his students, I could not have accomplished this endeavor. The people I have had the opportunity to work with over the course of this dissertation have been brilliant. I would like to thank Dr. Bon-Ki Ku from NIOSH, Dr. Maura Sheehan from West Chester University of Pennsylvania, and Timothy Klein from TAK Industries, LLC. Their willingness to collaborate despite the obstacle of distance was greatly appreciated. My dissertation committee was wonderful to work with and I would like to thank them for their time and expertise. Their advice allowed me to conduct meaningful research. I would like to thank Lauren Gant for volunteering her vibration expertise and assistance with conducting measurements. I am very grateful to Adele Bonney for her rather large role in helping me improve my writing. I would like to thank the organizations that provided funding for this research: NIOSH Heartland Center for Occupational Health and Safety pilot grant (T420H008491), and a University of Iowa Executive Council of Graduate and Professional Students Research Grant, and a NIOSH KO1 Award (OH009255). I would also like to thank the Heartland Center for Occupational Safety and Health for their financial support and training. 4 Without the support of my lab mates (Will Cyrs, Lorenzo Cena, Eric Sawvel, Dane Boysen, Sabah Saleh, Barry Hill, Javier Santalla, and Michael Humann), graduate student support group (Dr. Kathleen Staley, and the other students), weekly dissertation group (Alysha Myers and Michael Humann), friends, and family, I would never have been able to complete this degree. I cannot thank you enough. iv ABSTRACT This work strived to increase knowledge of assessing airborne nanoparticles in the workplace by characterizing nanoparticle concentrations in a workplace using direct- reading instruments, evaluating a DC2000CE diffusion charger, and the creation of a personal diffusion battery (pDB). Direct-reading instruments were used with aerosol mapping and task monitoring to evaluate airborne nanoparticle concentrations in an apparel company that produces waterproof jackets composed of polytetrafluoroethylene membrane laminated fabric. Jacket production required that sewn seams be sealed with waterproof tape applied with hot air (600°C). Particle number concentrations were greater in the sewing and sealing areas than the office area while respirable mass was negligible throughout the facility. The breathing zone particle number concentrations of the workers who sealed the sewn seams were highly variable and significantly greater when sealing seams than when conducting other tasks (p<0.0001). The effectiveness of the canopy hoods used to ventilate sealing operations was poor. These measurements support the idea that work places where hot processes are conducted may have substantially greater concentrations of airborne nanoparticles than background measurements even with control measures in place. Laboratory tests were conducted to evaluate a commercially available diffusion 5 charger, the DC2000CE, that measures nanoparticle surface area concentration. The surface area concentrations of unimodal and multimodal polydispersed aerosols measured by the DC2000CE were less than the surface area concentrations measured by the reference instruments. The differences in results were attributed to a difference of measuring active versus geometric surface area concentration and the design of the DC2000CE. The maximum measurable active surface area concentration (2,500 mm2 m-3) was found to be greater than the manufacturer stated maximum v