The effect of simulated air conditions on N95 filtering facepiece respirators performance

Abstract

The objective of this study was to determine the effect of several simulated air environmental conditions on the particle penetration and the breathing resistance of two N95 filtering facepiece respirator (FFR) models. The particle penetration and breathing resistance of the respirators were evaluated in a test system developed to mimic inhalation and exhalation breathing while relative humidity and temperature were modified. Breathing resistance was measured over 120 min using a calibrated pressure transducer under four different temperature and relative humidity conditions without aerosol loading. Particle penetration was evaluated before and after the breathing resistance test at room conditions using a sodium chloride aerosol measured with a scanning mobility particle sizer. Results demonstrated that increasing relative humidity and lowering external temperature caused significant increases in breathing resistance (p < 0.001). However, these same conditions did not influence the penetration or most penetrating particle size of the tested FFRs. The increase in breathing resistance varied by FFR model suggesting that some FFR media are less influenced by high relative humidity.

A computational model for predicting changes in infection dynamics due to leakage through N95 respirators

“…These complexities were not addressed in the study, as a rigid mannequin and steady suction was used in the experiments. Previous studies have designed respirable mannequins that are capable of mimicking the breathing cycle 34 . The current approach can accommodate such a mannequin provided that the scan frequency of the CT image is higher than the breathing cycle of the mannequin.…”

The effects of face mask specifications on work of breathing and particle filtration efficiency

“…For N95 FFRs, we have used the previously reported values for the physical characteristics of the N95 3M8510 (FFR1) listed in Table 1 [30] , while for the surgical mask such data were not available. For the surgical mask, the reported pressure drop were 2.667 ± 0.137 mmH2O with the KFDA protocol (constant flow rates of 30 lit/min) [24] .…”

Fluid Dynamics of Respiratory Infectious Diseases

“…Indeed, increased humidity, for example, may affect filter charge. Data collected in various humidities with varying airflows are conflicting (62)(63)(64)(65).…”