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FFRs with Exhalation Valves as Source Control
A technical report published by NIOSH on Dec. 9, 2020, discusses the results of a study concerning the extent to which filtering facepiece respirators (FFRs) with an exhalation valve provide source control to reduce particle emissions. The study tested three mitigation strategies for reducing particle emissions: covering the valve from inside the respirator with an electrocardiogram (ECG) pad, covering the valve with surgical tape, and covering the exterior of the respirator with a surgical mask. NIOSH performed a total of 1,125 tests on 13 FFR models. The tests measured particle penetration with respirators in both the inward position (airflow in the direction of inhaled breath) and the outward position (airflow in the direction of exhaled breath). Tests were performed at three flow rates: 25, 55, and 85 liters per minute (lpm).
The following information describes penetration of particles through the filter with respirators in the outward position (airflow channeled in the direction of exhalation). See page 14 for more information.
From “Filtering Facepiece Respirators with an Exhalation Valve: Measurements of Filtration Efficiency to Evaluate Their Potential for Source Control”:
“FFRs with an exhalation valve provide respiratory protection to the wearer and—according to the findings from this study—can also reduce particle emissions to levels similar to or better than those provided by surgical masks and unregulated barrier face coverings. This study shows that modifications to these respirators can further reduce particle emissions.”
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SOURCE
NIOSH: “Filtering Facepiece Respirators with an Exhalation Valve: Measurements of Filtration Efficiency to Evaluate Their Potential for Source Control” (December 2020).
