Evaluation of Betacoronavirus OC43 and SARS-CoV-2 Elimination by Zefero Air Sanitizer Device in a Novel Laboratory Recirculation System

Abstract

Indoor air sanitizers contrast airborne diseases and particularly severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)/Coronavirus disease 2019 (COVID-19). The commercial air sanitizer Zefero (Cf7 S.r.l., San Giovanni La Punta, Italy) works alternatively using a set of integrated disinfecting technologies (namely Photocatalysis/UV mode) or by generating ozone (Ozone mode). Here we evaluated the virucidal efficacy of Zefero setup modes against human Betacoronavirus OC43 and SARS-CoV-2. For this purpose, we designed a laboratory test system in which each virus, as aerosol, was treated with Photocatalysis/UV or Ozone mode and returned into a recirculation plexiglass chamber. Aerosol samples were collected after different times of exposure, corresponding to different volumes of air treated. The viral RNA concentration was determined by qRT-PCR. In Photocatalysis/UV mode, viral RNA of OC43 or SARS-CoV-2 was not detected after 120 or 90 min treatment, respectively, whereas in Ozone mode, viruses were eliminated after 30 or 45 min, respectively. Our results indicated that the integrated technologies used in the air sanitizer Zefero are effective in eliminating both viruses. As a reliable experimental system, the recirculation chamber developed in this study represents a suitable apparatus for effectively comparing the disinfection capacity of different air sanitizers.

Inactivation of aerosolized SARS‐CoV ‐2 by 254 nm UV‐C irradiation

“…Buonanno et al 29 investigated the inactivation of aerosolized common cold coronaviruses and influenza, determining low doses ranging from 1.2 to 3.8 mJ/cm 2 to achieve 3‐log reduction, using far‐UV‐C light at 222 nm. Finally, only one study worked with SARS‐CoV‐2 using a commercial system employing UV‐C or ozone to inactivate this virus and the seasonal HCoV‐OC43 31 . Their experimental setup did not facilitate the determination of irradiation doses or recovery of infectious viruses.…”

“… 24 Although highly relevant, UV‐C mediated decontamination of aerosolized viruses, in particular SARS‐CoV‐2, is an understudied topic. We are aware of only four publications 28 , 29 , 30 , 31 trying to assess the stability of coronaviruses in aerosols. Walker et al, 28 demonstrated that murine beta coronaviruses aerosols are highly susceptible to 254 nm UV‐C‐irradiation, between 7 and 10 times more than adenoviruses and bacteriophage MS2.…”

“…Finally, only one study worked with SARS‐CoV‐2 using a commercial system employing UV‐C or ozone to inactivate this virus and the seasonal HCoV‐OC43. 31 Their experimental setup did not facilitate the determination of irradiation doses or recovery of infectious viruses. They reported that after 120 and 90 min of irradiation for HCoV‐OC43 and SARS‐CoV‐2, respectively, viral RNA was no longer detected by qRT‐PCR.…”

“…For inactivation of virus‐containing aerosols in general 28 , 29 , 30 and coronaviruses in particular, literature is sparse and there is virtually no information on minimal UV‐C doses necessary to inactivate SARS‐CoV‐2. 31 In this context, we designed, built, and established a test bench to evaluate UV‐C mediated SARS‐CoV‐2 inactivation in aerosols and determine the potency of a low dose of 254 nm UV‐C irradiation to reduce viral titers.…”

Ozone application in different industries: A review of recent developments

“… Hu et al [189] (2021) Aqueous 4.5, 9, 18, 36 mg/L 1, 5, 10 min – – Virus solution inoculated into Vero E6 cells) Full inactivation of virus stock (4 × 10 3 PFU/mL) in<1 min, by 36 mg/L aqueous ozonation. Nicolò et al [190] (2022) Gaseous 5 g/h in a chamber of 0.033 m 3 15, 30 min – – Aerosol sampling The virus was fully eliminated after 30 mins of ozone exposure. Takeda et al [191] (2021) Glycerol 200, 500, 1000, 2000 ppm 20 sec , 1 h, & 24 h – – Virus solution in DMEM and FBS media ≥99.91 % of the virus was inactivated by ozonated glycerol (500 ppm, 1 h) at 20 % of FBS concentration.…”