In Situ Evaluation of Filter Media Modified by Biocidal Nanomaterials to Control Bioaerosols in Internal Environments

Controlling the bioaerosol present in indoor environments has been evidenced to be extremely necessary. An alternative is to develop filter media for air conditioners that have biocidal properties. This study aimed to verify the biocidal effect of a high-efficiency particulate air (HEPA) filter medium modified with the deposition of nanoparticles on its surface. For this purpose, Ag, TiO₂, and Ag/TiO₂ nanoparticles were used and the antimicrobial activities of these nanomaterials against Escherichia coli, Staphylococcus aureus, and Candida albicans microorganisms were evaluated, as well as the biocidal efficacy of the modified HEPA filter with these nanomaterials in a real environment. The percentages of elimination obtained for the Ag, TiO₂, and Ag/TiO₂ nanomaterials, respectively, were 53%, 63%, and 68% (E. coli); 67%, 67%, and 69% (S. aureus); and 68%, 73%, and 75% (C. albicans). The HEPA filter media had their surfaces modified by aspersion and deposition of Ag, TiO₂, and Ag/TiO₂ nanomaterials. We could conclude that the nanoparticles adhered to the filter medium do not affect its permeability. The modified filters were arranged in an internal environment (bathroom) for the collection of the bioaerosols, and after the collection, the filter cake was plated and arranged to grow in a liquid medium. The results showed that the filters have 100% of biocidal action in passing air, and 55.6%, 72.2%, and 81% of inhibition to microbial growth in their surface for modification with Ag, TiO₂, and Ag/TiO₂, respectively, compared to unmodified filters.