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Modifications can improve effectiveness of FRRs with exhalation valve, NIOSH says

Photo: Centers for Disease Control and Prevention

Washington — Filtering facepiece respirators with an exhalation valve can be modified to reduce respiratory particle emissions – improving their effectiveness as a source control, according to a technical report recently published by the NIOSH National Personal Protective Laboratory.

The report notes that FFRs with an exhalation valve “provide the wearer with a level of protection similar to that of an FFR without an exhalation valve.” However, FFRs with an exhalation valve allow for respiratory secretions to be expelled by the wearer and the potential spread of diseases such as COVID-19 through “unfiltered, virus-laden aerosols.”

FFRs with an exhalation valve have filters for inhaled air and open to allow exhaled breath through the valve and the filter media. These kinds of FFRs have the ability to “increase the wearer’s comfort at high work rates and be suitable for longer periods of use.”


The report provides strategies to help improve the effectiveness of FFRs with an exhalation valve. Putting 13 FFR models through a combined 1,125 tests, researchers found that adding an electrocardiogram pad to the inside of this kind of FFR was the best mitigation strategy. Using surgical tape was the next best strategy, while covering an FFR with a surgical mask was the least effective.

“These results represent one of the first measurements of particle penetration through FFRs with an exhalation valve that are tested in an outward position,” the report states, “and the findings have important implications for guidance on source control and mitigation.”

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