Emerging technologies for airborne respiratory virus mitigation: A systematic review

Multiples technologies have been developed to inactivate airborne viruses in built environments, yet their relative effectiveness and practical challenges have not been comprehensively compared. This systematic review assesses the efficacy, operational considerations, and real-world applicability of these technologies in built environments. We employed PRISMA approach along with targeted keywords to identify relevant studies published in peer-reviewed journals. We extracted data and information pertaining to the application of several methods, including germicidal ultraviolet (GUV) irradiation, ozonation, non-thermal plasma (NTP), and nanomaterial-based technologies from studies that met our objectives and inclusion criteria. Out of 2329 potential articles, 56 studies were included. GUV irradiation achieved airborne virus reductions exceeding 1-log₁₀ (90 %) in most cases, with variability depending on GUV wavelength, dose and experimental condition. Airborne virus reductions were higher with 222-nm GUV than with 254-nm GUV (p = 0.075), indicating a trend toward greater efficacy at 222 nm. Respiratory viruses exhibited significantly greater susceptibility to GUV inactivation than their surrogate bacteriophages (p = 2.97 × 10⁻⁶). Ozone was most effective at higher relative humidity, achieving up to a 4-log₁₀ (99.99 %) reduction for influenza virus at 1.7 ppm over 80 min. NTP achieved virus reductions ranging from 1 to 6.5-log₁₀, with greater reductions observed at longer exposure times. Nanomaterial-based methods achieved virus inactivation between 0.34 to 6 log₁₀, with the highest reductions observed for influenza A (H1N1). All evaluated technologies have demonstrated the ability to inactivate airborne viruses under laboratory conditions; however, their effectiveness varies with operational and experimental parameters as well as virus characteristics. Consequently, broad endorsement and standardized guidance remain limited, owing to heterogeneous performance, safety considerations, and a paucity of rigorous real-world studies.