Comparison of two quantitative fit-test methods using N95 filtering facepiece respirators

Area of Science:

• Occupational Health
• Respiratory Protection
• Industrial Hygiene

Background:

• Current regulations mandate annual respirator fit testing for occupational safety.
• Traditional quantitative fit testing (QNFT) is time-consuming and may not reflect real-world conditions.
• Evaluating respirator fit during dynamic work activities is crucial for effective protection.

Purpose of the Study:

• To compare respirator fit measurements obtained by a novel two-instrument real-time method with a standard ambient aerosol condensation nuclei counter quantitative fit test.
• To assess the feasibility of using real-time monitoring for respirator fit evaluation.
• To identify specific facial exercises that significantly impact respirator fit.

Main Methods:

• Sixteen subjects performed N95 filtering facepiece respirator fit tests using two protocols: a standard QNFT and a two-instrument real-time method.
• Simultaneous sampling of particle concentrations inside and outside the respirator was conducted with the real-time method.
• Spearman's rank correlation coefficients were used to compare fit factors between the two methods across various exercises.

Main Results:

• The two-instrument real-time fit test demonstrated high correlation (r > 0.7) with the single-instrument QNFT for the initial four exercises.
• Respirator fit was significantly altered during exercises involving facial movements, such as talking or grimacing.
• The real-time method provided comparable fit factor measurements to the standard QNFT.

Conclusions:

• The novel two-instrument real-time methodology shows promise as a viable alternative for assessing respirator fit.
• This method can potentially be used to evaluate respirator fit dynamically during work tasks.
• Understanding how facial movements affect fit is critical for optimizing respirator use in occupational settings.