Evaluation of a quantitative fit testing method for N95 filtering facepiece respirators

Area of Science:

• Occupational Health and Safety
• Respiratory Protection
• Industrial Hygiene

Background:

• Quantitative fit testing (QNFT) is crucial for respirator effectiveness.
• A clamp method was proposed to measure N95 filter penetration and assess faceseal leakage.
• Previous studies utilized this clamp for respirator performance evaluation.

Purpose of the Study:

• To evaluate the efficacy of a clamp method in measuring N95 filter penetration.
• To assess the clamp method's ability to determine accurate fit factors for N95 respirators.
• To compare QNFT results using the clamp method with established P100 filter performance.

Main Methods:

• Subjects underwent QNFT with elastomeric half-facepiece respirators using generated and ambient aerosols.
• N95 and P100 filters were used during fit testing in two phases, with and without simulated faceseal leakage.
• A clamp device measured N95 filter penetration, which was subtracted from total penetration to estimate faceseal leakage.

Main Results:

• Corrected N95 fit factors significantly differed from P100 fit factors in both study phases.
• No significant correlation was observed between corrected N95 fit factors and P100 fit factors.
• The clamp method's measurements of filter penetration were found to be unreliable.

Conclusions:

• The clamp method is not suitable for quantitative fit testing of N95 filtering facepiece respirators.
• The clamp method should not be used to assess the overall performance of N95 respirators.
• Current findings indicate limitations in using this clamp for accurate respiratory protection assessment.