Filtration of nanoparticles - Application to respiratory protecting devices

This study aims to determine how the respiratory protective devices (RPD), whose performances are qualified for particles above 100 nm, are effective for nanoparticles. Indeed, if the use of a collective filtration is inadequate, wearing a RPD is the last protection recommended.
A literature review showed that no research concerned the effectiveness of half-masks for nanoparticles. The test bench ETNA has been sized and built to overcome these lacks. Two half masks were tested according to different configurations:
-constant flow rate and cyclic flow rate (average flow of 84 L /min),
-particle size (from 5 to 100 nm),
-positions of the mask (sealed, usual, or with calibrated leaks).
The results show that, since the RPD contain high efficiency filter media (without charged fibers) for the most penetrating particle size (100 nm - 300 nm), the RPD is more efficient for nanoparticles. Furthermore, the results obtained in the presence of actual and calibrated leaks, highlighted the importance of faceseal leakages in determining the performance of RPD. A model for calculating the protection factor was established based on the balance between the airflow through the filter and the leak. This model was validated using measurements obtained in the presence of calibrated leaks, and applied for the analysis of our results in usual position.