Evaluating the Effect of Coated Filters and Pre-Filters on the Infectivity and Concentration of Aerosolized Phi6...

Development of efficient indoor air filtration technologies has gained prominence following the coronavirus disease 2019 (COVID-19) pandemic. The goal of this study is to evaluate the anti-viral efficacy of various copper and silver-based surface coatings for air filters using a standardized bioaerosol chamber and the enveloped bacteriophage Phi6 as a surrogate for respiratory viruses. Surface testing confirmed that all coatings exhibited anti-viral activity, with the specific copper-based coating formulation (B4) achieving complete inactivation of Phi6 virus within 10 min, A6 in 25 min, and VS-B in 60 min; early reductions in infectivity were primarily due to droplet desiccation. Aerosol experiments showed that high-efficiency particulate air (HEPA) filters and pre-filters substantially reduced viral infectivity even without coatings, with mechanical filtration causing a 1.0-2.0 log reduction, and high-efficiency grade GF-2 glass fiber filters eliminating detectable infectious virus. Coatings did not significantly enhance filtration efficiency, likely due to limited virus contact with coated surfaces. Used GF-2 filters demonstrated improved virus removal, attributed to particle accumulation and filter densification, while coatings did not alter the copy number of viruses passing through. VS-B coated filters exhibited lipophilic properties, suggesting additional functional benefits. This methodology highlights that while filter efficiency is primarily driven by mechanical entrapment and particle accumulation, the integrated surface coatings provide a self-sanitizing mechanism by inactivating trapped viral particles; the integration of ultraviolet (UV) light is proposed as a potential future research direction to enhance system efficacy further.