A Quantitative Assessment of the Total Inward Leakage of NaCl Aerosol Representing Submicron-Size Bioaerosol Through N95 Filtering Facepiece Respirators and Surgical Masks

Abstract

Respiratory protection provided by a particulate respirator is a function of particle penetration through filter media and through faceseal leakage. Faceseal leakage largely contributes to the penetration of particles through a respirator and compromises protection. When faceseal leaks arise, filter penetration is assumed to be negligible. The contribution of filter penetration and faceseal leakage to total inward leakage (TIL) of submicron-size bioaerosols is not well studied. To address this issue, TIL values for two N95 filtering facepiece respirator (FFR) models and two surgical mask (SM) models sealed to a manikin were measured at 8 L and 40 L breathing minute volumes with different artificial leak sizes. TIL values for different size (20–800 nm, electrical mobility diameter) NaCl particles representing submicron-size bioaerosols were measured using a scanning mobility particle sizer. Efficiency of filtering devices was assessed by measuring the penetration against NaCl aerosol similar to the method used for NIOSH particulate filter certification. Results showed that the most penetrating particle size (MPPS) was ~45 nm for both N95 FFR models and one of the two SM models, and ~350 nm for the other SM model at sealed condition with no leaks as well as with different leak sizes. TIL values increased with increasing leak sizes and breathing minute volumes. Relatively, higher efficiency N95 and SM models showed lower TIL values. Filter efficiency of FFRs and SMs influenced the TIL at different flow rates and leak sizes. Overall, the data indicate that good fitting higher-efficiency FFRs may offer higher protection against submicron-size bioaerosols.

Assessment of a respiratory face mask for capturing air pollutants and pathogens including human influenza and rhinoviruses

“…As such, the test mask would be expected to provide filtration efficiency for combustion products (40) in addition to the efficiency demonstrated for sodium chloride (a surrogate for allergens and pollutants such as PM 2.5 ). As discussed above for filtration of infectious agents, comparative testing of N95 facepiece respirators and surgical masks has shown that surgical masks are less effective for filtration of sodium chloride aerosols (41).…”

“…Any increased benefits of N95 facepiece respirators such as the test mask over surgical masks are likely dependent upon the ergonomic fit of the mask to the wearer's face. This is because in the absence of a tight fit, inward leakage would be expected to dominate over filter penetration as the predominant mode of entry of particulates/aerosols containing infectious agents into the mask, regardless of the type of mask (30)(31)(32)41). A controlled clinical study failed, however, to reveal a significant difference in protection of healthcare workers using fit-tested vs. nonfit-tested N95 masks (42).…”

N95 filtering facepiece respirators do not reliably afford respiratory protection during chest compression: A simulation study

“…Notably, in 94% of the participants in the PPG, the FF decreased to <100 during at least one session of chest compression. Facepiece respirators only work properly when the face seal is tight [17,18]. Body movements during chest compression are both dynamic and intense, and sweat further compromises respirator fit, creating a gap permitting disease transmission.…”

Effectiveness of activated carbon masks in preventing anticancer drug inhalation

“…If the mask does not fit well, its filtration efficiency is decreased as air bypasses the filter. Rengasamy et al reported that leaks were greater in pleats-type masks than in stereoscopic-type masks [17]. However, in this study condition, the mask which cut to 100 cm 2 was pinched with two funnels, and was ventilated as a flat shape.…”