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Comparison of five methods for fit-testing N95 filtering-facepiece respirators
Christopher C Coffey1, Robert B Lawrence, Ziqing Zhuang
1Division of Respiratory Disease Studies, National Institute for Occupational Safety and Health, Morgantown, West Virginia, USA.
Applied Occupational and Environmental Hygiene
|October 5, 2002
Summary
The ambient aerosol method using the TSI PortaCount Plus best identified poorly fitting N95 respirators. This method showed the lowest error rate for assigning respirators, ensuring better wearer protection.
Area of Science:
- Occupational Health and Safety
- Respiratory Protection
- Industrial Hygiene
Background:
- Proper fit of N95 filtering-facepiece respirators is crucial for effective protection against airborne hazards.
- Existing fit-testing methods vary in their ability to accurately identify respirators with inadequate face seals.
- Understanding fit-testing method performance is essential for selecting reliable procedures.
Purpose of the Study:
- To evaluate and compare the effectiveness of five different fit-testing methods for N95 respirators.
- To determine which fit-testing methods minimize both false positives (alpha errors) and false negatives (beta errors).
- To identify the most reliable method for detecting poorly fitting N95 filtering-facepiece respirators.
Main Methods:
- Five fit-testing methods were assessed: Bitrex, saccharin, ambient aerosol (TSI PortaCount Plus), modified ambient aerosol (TSI PortaCount Plus with N95-Companion), and generated aerosol (corn oil).
- Twenty-five subjects tested eighteen models of NIOSH-certified N95 respirators using each method.
- Filter media penetration was measured to isolate face-seal leakage and adjust fit factors, comparing results to simulated workplace protection factors.
Main Results:
- Beta errors (passing a poorly fitting respirator) ranged from 3% to 11%, while alpha errors (failing a well-fitting respirator) ranged from 51% to 84%.
- The ambient aerosol (TSI PortaCount Plus) and generated aerosol methods were superior in identifying poorly fitting respirators compared to saccharin, Companion, and Bitrex.
- The ambient aerosol method using the TSI PortaCount Plus demonstrated the lowest overall assignment error rate when both error types were considered.
Conclusions:
- The choice of fit-testing method significantly impacts the accuracy of identifying poorly fitting N95 respirators.
- The ambient aerosol method with the TSI PortaCount Plus offers the most reliable performance in detecting inadequate respirator fit.
- Occupational health professionals should consider these error rates when selecting N95 respirator fit-testing protocols.