Evaluating layer contributions and salt coating effects on mask performance

The impact of respiratory diseases is vast and multifaceted, affecting individuals, healthcare systems, and global economies. In response to the spread of respiratory pathogens, masks and respirators have become pivotal, demonstrating their capability to mitigate transmission. However, the limitations of conventional face masks or respirators, such as their single-use nature, environmental impact, and the risk of contact-based transmission, have accelerated the development of antimicrobial masks. Designing effective antimicrobial masks requires a deep understanding of the properties of each layer and the identification of an optimal configuration to enhance their protective efficiency. In this study, we investigated the filtration performance, including filtration efficiency and breathability, of individual layers in conventional 3-ply masks and stacked spunbond (SB) fabrics with and without salt coating, under both dry and wet fabric conditions. We aimed to elucidate the filtration efficiency of each mask layer with respect to particle size and type (NaCl aerosols, DOP aerosols), with particular focus on the impact of salt-coated SB fabric and its application. While bare fabrics showed a decrease in filtration efficiency with increased wetness, salt-coated fabrics exhibited enhanced filtration efficiency. Importantly, evaluating the efficacy of a stack comprised of salt-coated SB fabrics across diverse antimicrobial respiratory devices highlighted its efficacy as both the outermost layer in a 3-ply mask and as a mask covering (i.e., a supplementary layer over a mask or respirator). This investigation not only emphasizes the significance of salt-coated antimicrobial technology in mitigating disease transmission but also offers a practical approach for adeptly implementing this technology in respiratory protection devices.