Date of Graduation


Document Type


Degree Type



Statler College of Engineering and Mineral Resources


Industrial and Managements Systems Engineering

Committee Chair

Warren Myers

Committee Member

Gary Winn

Committee Member

Ziqing Zhuang

Committee Member

Majid Jaridi

Committee Member

Jeremy Gouzd

Committee Member

Anna Allen


The role of powered air- purifying respirators (PAPRs) in healthcare settings during infectious diseases outbreaks and highly contagious pathogens (e.g., SARS, HINI, Ebola, COVID etc.) has attracted much interest based on the level of respiratory protection they provide and their many positive user features. A common practice among healthcare workers to minimize airborne contaminant exposure has been to use surgical masks or N95 filtering facepiece respirators (FFRs). Surgical masks have been shown to offer minimal respiratory protection and while N95 FFRs offer better respiratory protection, they are not comfortable to use for a prolonged period. With current PAPR designs, exhaled air from the wearer is not filtered at all before release to the environment. This design feature suggests a potential for biocontamination when using PAPRs in an operating room sterile field condition. The objective of this research is to evaluate the bacterial shedding from the respiratory tract of healthcare workers while wearing PAPRs and half-mask respirators on sterile conditions in operating rooms (ORs).

A randomized, simulated workplace study was conducted to compare the bacterial shedding from respiratory tracts of 9 teams of 2 participants each wearing six different types of respiratory protection devices (RPD), including an FDA approved surgical mask (SM), and five different NIOSH certified respirators. The result showed that the bacterial contamination produced by a pair of subjects wearing the N95 FFR without exhalation valves, the PAPR with APF=25 and the PAPR with APF=1000 was not significantly different than the contamination resulting from wearing the SM. However, the bacterial contamination resulting from using the N95 FFR with exhalation valve and elastomeric half-mask respirator, EHMR with exhalation valve was found to be significantly higher than the bacterial contamination resulting from wearing the SM.