Graduation Date

Spring 5-7-2026

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Programs

Environmental Health, Occupational Health, and Toxicology

First Advisor

Matthew Nonnenmann

Abstract

Asthma is a common respiratory health issue among farmers in the United States. Despite known hazardous respiratory exposures, the prevalence of asthma in agriculture remains lower than in the general population. Using respirators has been proven to reduce agricultural exposures and protect against respiratory health conditions, including asthma. However, factors such as breathing resistance and user comfort, among others, have discouraged consistent use among farm operators, especially during activities with high respiratory exposure risks. Specialized respirators, such as powered air-purifying respirators (PAPRs) equipped with blowers, supply filtered air through face-covering hoods, protecting against airborne exposures while providing comfort and less breathing resistance. Yet, the operation of these devices generates internal hood noise, which can lead to reduced speech clarity, increased cognitive load, and mild to severe hearing loss among users.

This dissertation aimed to explore the relationship between exposure, protection, and communication in occupational respiratory health. The Central States Center for Agricultural Safety and Health (CS-CASH) Farm and Ranch Health and Safety Survey (FRHSS) data from 2018, 2020, and 2023 were analyzed to examine asthma prevalence and related respiratory exposures (Chapter 1). The overall asthma prevalence was 4.7%, with females exhibiting a higher prevalence (5.3%) than males (4.6%). The modified rhyme test was employed to assess the communication performance of two commercially used PAPRs (Chapter 2). Overall, 3M PAPRs received better performance ratings than MAXAIR across experimental trials, despite recording louder internal noise. Additionally, internal noise in both PAPR models was extensively measured using various manikin sizes (Chapter 3). Our findings showed that head size was the most significant factor affecting PAPR noise, accounting for roughly 39% of the internal noise variability, compared to the PAPR models (21%).

The results demonstrate the dual challenge of respiratory health hazards and the limitations of current respiratory protection for agricultural workers. These findings underscore the need for more user-focused respirator design approaches, targeted awareness campaigns, and policies that promote both respiratory health protection and ease of use.

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Available for download on Tuesday, March 09, 2027

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