Semester

Fall

Date of Graduation

2021

Document Type

Dissertation

Degree Type

PhD

College

Statler College of Engineering and Mineral Resources

Department

Industrial and Managements Systems Engineering

Committee Chair

Jeremy Gouzd

Committee Co-Chair

Eun Gyung (Emily) Lee

Committee Member

Warren Myers

Committee Member

Michael McCawley

Committee Member

Gary Winn

Committee Member

Michael Kashon

Abstract

ABSTRACT

AEROSOL SAMPLING STRATEGY: Effect of Particle Transfer to Sampler Covers and Estimation of Conversion Factors between the United States and German Methods for Quartz sampling

GODWIN A. EREKAIFE

In many countries, communities of experts, including industrial hygienists, have developed unique sampling strategies to determine workers’ exposure to aerosolized particles (e.g., metals, wood dust etc.). However, using different sampling and analytical methods for the same chemical often results in different exposure levels for a similar exposure group (SEG). The exposure discrepancies among different countries that are caused by using different measurement strategies are not always systematically defined. Therefore, this study investigates aerosol sampling strategies in two parts: 1) the potential for particle loss to the sampler covers during sample transportation to improve sampling methodology and prevent underestimation of mass concentrations (Chapter 2) and 2) determining the relationship between exposure measurements of respirable crystalline silica (RCS) using the U.S. measurement strategy (NIOSH method) and the German strategy (IFA method), and to develop a conversion factor (or equation) to adjust for differences (Chapter 3). Below is a result summary of the investigation.

Effects of particle transfer to the covers of aerosol samplers during transportation: Wood dust samples were collected in a sanding chamber using four different samplers: closed-face cassettes (CFC), CFC with Accu-CAP™ inserts, disposable inhalable samplers (DIS), and Institute of Occupational Medicine (IOM). Welding fumes were collected in a walk-in chamber using the same samplers, with Solu-Sert™ replacing Accu-CAP. The samples were divided into two groups, with one group transported by air and the other by land. They were returned in the same manner and analyzed gravimetrically for wood dust and chemically for welding fumes. For wood dust, IOM showed a significantly higher percentage of particles transferred to the covers compared with the other samplers regardless of the transportation mode, while other samplers did not. For the welding fumes samples, most samples showed nondetectable amounts of the analyte on the covers. Overall, this study confirms that particle transfer to sampler covers during transport highly depends upon the transportation mode, particle size ranges, and the sampler type for wood dust, whereas particle transfer seems minimal for welding fumes. Although the findings of this study are based on two materials and limited sample sizes, occupational professionals should account for this transfer when handling and analyzing samples in practice.

Estimation of conversion factors between the United States and German methods for quartz sampling: This study compared the sampling and analytical methods of each country to determine RCS exposures in three ways: 1) spiked sample analysis, to verify the differences between both countries’ analytical methods, 2) environmental chamber study, where side-by-side samples were collected under environmentally controlled conditions to determine the differences of samplers along with the analytical difference, and 3) field study, to determine the impact of uncontrolled environmental conditions and unknown workplace characteristics on the results by each method. Overall, differences between the two country’s methods were observed and the calculated conversion factor was 0.71 when converting RCS concentrations from GK2.69 to FSP-10 cyclones using infrared spectroscopy (IR). The findings of this study will fill the knowledge gap associated with exposure discrepancies between two countries that are caused by using different measurement strategies. Most importantly, by using the outputs of this study, larger databases can be created from several smaller repositories of existing data and can be exploited to determine long-term exposure trends and evaluate exposure control methods. Finally, the application of the findings would not be limited to just these two countries but can extend to other countries that have adopted either NIOSH or IFA methods.

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