The use of nanoparticles in industry has increased spectacularly over the past few years. Additionally, nanoscale particles seem to be the cause of new professional exposure situations. Due to their size, these particles may build up within the respiratory tract and may even reach the nervous system via the nasal passages; for this reason, it is generally recommended to wear respiratory protective devices (RPDs) in situations where collective protection is impossible to implement or inadequate. Here, we present the test bench ETNA designed to study the efficiency of RPDs in the presence of nanoparticles. The results of the efficiency measurement of two RPDs for two positions (sealed and unsealed) on a Sheffield head, for two inhalation configurations (constant flow and cyclic flow), and for two different particle size distributions of NaCl aerosol (one centered on 13 nm and the other on 59 nm) are presented below. The measurements indicate that when the leaks are negligible at the interface mask/head, the efficiency of RPD is greater for nanoparticles. For major leaks, the device's protection factor changes independently of the size of the particles. Furthermore, no trends with respect to the effect of the respiration type (constant-flow and cyclic-flow tests) have been shown on the device's protection factor.