Inactivation of Human Coronavirus by FATHHOME's Dry Sanitizer Device: Rapid and Eco-Friendly Ozone-Based Disinfection of SARS-CoV-2

The application of ozone within the food industry, mode of action, current and future applications, and regulatory compliance

The food industry faces numerous challenges today, with the prevention and reduction of microbial contamination being a critical focus. While traditional chemical-based methods are effective and widely used, rising energy costs, the development of microbial tolerances, and growing awareness of the ecological impact of chemical biocides have renewed interest in novel biocides. Ozone, in both its gaseous and aqueous forms, is recognized as a potent disinfectant against bacteria, viruses, and fungi due to its high oxidation potential. Our review highlights several studies on the applications of ozone within the food industry, including its use for surface and aerosol disinfection and its capacity to reduce viable Listeria monocytogenes, a pertinent foodborne pathogen harbouring environmental and biocide stress tolerances and biofilm former. We also explore the use of ozone in food treatment and preservation, specifically on blueberries, apples, carrots, cabbage, and cherry tomatoes. While ozone is an effective disinfectant, it is important to consider material incompatibility, and the risks associated with prolonged human exposure to high concentrations. Nevertheless, for certain applications, ozone proves to be an efficacious and valuable alternative or complementary method for microbial control. Compliance with the biocide products regulation will require ozone device manufacturers to produce proven efficacy and safety data in line with British standards based on European standards (BS EN), and researchers to propose adaptations to account for ozone's unique properties.

Ozone therapy in dentistry: An overview of the biological mechanisms involved (Review)

At low medically-relevant concentrations, ozone serves as an oxidant with a wide spectrum of antimicrobial activity and the ability to promote healing and reduce inflammation. Despite providing therapeutic benefits in a range of diseases, certain adverse effects and contraindications of ozone treatment must be considered. These are primarily related to toxicity from inhalation and systemic types of administration and can be avoided by following relevant guidelines and recommendations. Ozone therapy has been implemented in a number of fields of dentistry and the most commonly used formulations for the oral cavity are gaseous ozone, ozonized water and ozonized oil. The biological mechanisms underlying the molecular effects of ozone have been increasingly reported, but currently remain largely unknown. The aim of the present review was to provide an overview of the mechanisms involved in ozone interaction with dental tissues. The present review focused on relevant evidence regarding the effect of ozone on dental tissues, including periodontal structures, dental cells, enamel and dentine, considering in vitro studies in addition to animal and human studies. A variety of biological mechanisms acting through multiple biochemical target pathways were reported to be responsible for the therapeutic effects of ozone. The main beneficial effects of ozone occurred in the following domains: antimicrobial activity, remineralization and microstructural changes of hard dental tissues, immunomodulation and biostimulation of dental and periodontal cells. Additional research could provide further insights into the use of ozone, increase its use for broader clinical applications and assist in the selection of targeted protocols.

Field trial assessing the antimicrobial decontamination efficacy of gaseous ozone in a public bus setting

The widespread COVID-19 pandemic caused by the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) necessitated measures aimed at preventing the spread of SARS-CoV-2. To mitigate the risk of fomite-mediated transmission, environmental cleaning and disinfection regimes have been widely implemented. However, conventional cleaning approaches such as surface wipe downs can be laborious and more efficient and effective disinfecting technologies are needed. Gaseous ozone disinfection is one technology which has been shown to be effective in laboratory studies. Here, we evaluated its efficacy and feasibility in a public bus setting, using murine hepatitis virus (a related betacoronavirus surrogate) and the bacteria Staphylococcus aureus as test organisms. An optimal gaseous ozone regime resulted in a 3.65-log reduction of murine hepatitis virus and a 4.73-log reduction of S. aureus, and decontamination efficacy correlated with exposure duration and relative humidity in the application space. These findings demonstrated gaseous ozone disinfection in field settings which can be suitably translated to public and private fleets that share analogous characteristics.

Ozone application in different industries: A review of recent developments

Ozone - a powerful antimicrobial agent, has been extensively applied for decontamination purposes in several industries (including food, water treatment, pharmaceuticals, textiles, healthcare, and the medical sectors). The advent of the COVID-19 pandemic has led to recent developments in the deployment of different ozone-based technologies for the decontamination of surfaces, materials and indoor environments. The pandemic has also highlighted the therapeutic potential of ozone for the treatment of COVID-19 patients, with astonishing results observed. The key objective of this review is to summarize recent advances in the utilisation of ozone for decontamination applications in the above-listed industries while emphasising the impact of key parameters affecting microbial reduction efficiency and ozone stability for prolonged action. We realise that aqueous ozonation has received higher research attention, compared to the gaseous application of ozone. This can be attributed to the fact that water treatment represents one of its earliest applications. Furthermore, the application of gaseous ozone for personal protective equipment (PPE) and medical device disinfection has not received a significant number of contributions compared to other applications. This presents a challenge for which the correct application of ozonation can mitigate. In this review, a critical discussion of these challenges is presented, as well as key knowledge gaps and open research problems/opportunities.

Inactivation of multiple human pathogens by Fathhome's dry sanitizer device: Rapid and eco-friendly ozone-based disinfection

SARS-CoV-2 spread rapidly, causing millions of deaths across the globe. As a result, demand for medical supplies and personal protective equipment (PPE) surged and supplies dwindled. Separate entirely, hospital-acquired infections have become commonplace and challenging to treat. To explore the potential of novel sterilization techniques, this study evaluated the disinfection efficacy of Fathhome's ozone-based, dry-sanitizing device by dose and time response. Inactivation of human pathogens was tested on non-porous (plastic) surfaces. 95.42-100% inactivation was observed across all types of vegetative microorganisms and 27.36% inactivation of bacterial endospores tested, with no residual ozone detectable after completion. These results strongly support the hypothesis that Fathhome's commercial implementation of gas-based disinfection is suitable for rapid decontamination of a wide variety of pathogens on PPE and other industrially relevant materials.

Inactivation of SARS-CoV-2 and Other Human Coronaviruses Aided by Photocatalytic One-Dimensional Titania Nanotube Films as a Self-Disinfecting Surface

SARS-CoV-2 and its variants that continue to emerge have necessitated the implementation of effective disinfection strategies. Developing self-disinfecting surfaces can be a potential route for reducing fomite transmissions of infectious viruses. We show the effectiveness of TiO₂ nanotubes (T_NTs) on photocatalytic inactivation of human coronavirus, HCoV-OC43, as well as SARS-CoV-2. T_NTs were synthesized by the anodization process, and their impact on photocatalytic inactivation was evaluated by the detection of residual viral genome copies (quantitative real-time quantitative reverse transcription polymerase chain reaction) and infectious viruses (infectivity assays). T_NTs with different structural morphologies, wall thicknesses, diameters, and lengths were prepared by varying the time and applied potential during anodization. The virucidal efficacy was tested under different UV-C exposure times to understand the photocatalytic reaction's kinetics. We showed that the T_NT presence boosts the inactivation process and demonstrated complete inactivation of SARS-CoV-2 as well as HCoV-OC43 within 30 s of UV-C illumination. The remarkable cyclic stability of these T_NTs was revealed through a reusability experiment. The spectroscopic and electrochemical analyses have been reported to correlate and quantify the effects of the physical features of T_NT with photoactivity. We anticipate that the proposed one-dimensional T_NT will be applicable for studying the surface inactivation of other coronaviruses including SARS-CoV-2 variants due to similarities in their genomic structure.

Ozone Eliminates SARS-CoV-2 from Difficult-to-Clean Office Supplies and Clinical Equipment

(1) Background: Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) continues to cause profound health, economic, and social problems worldwide. The management and disinfection of materials used daily in health centers and common working environments have prompted concerns about the control of coronavirus disease 2019 (COVID-19) infection risk. Ozone is a powerful oxidizing agent that has been widely used in disinfection processes for decades. The aim of this study was to assess the optimal conditions of ozone treatment for the elimination of heat-inactivated SARS-CoV-2 from office supplies (personal computer monitors, keyboards, and computer mice) and clinical equipment (continuous positive airway pressure tubes and personal protective equipment) that are difficult to clean. (2) Methods: The office supplies and clinical equipment were contaminated in an area of 1 cm2 with 1 × 104 viral units of a heat-inactivated SARS-CoV-2 strain, then treated with ozone using two different ozone devices: a specifically designed ozonation chamber (for low-medium ozone concentrations over large volumes) and a clinical ozone generator (for high ozone concentrations over small volumes). SARS-CoV-2 gene detection was carried out using quantitative real-time polymerase chain reaction (RT-qPCR). (3) Results: At high ozone concentrations over small surfaces, the ozone eliminated SARS-CoV-2 RNA in short time periods-i.e., 10 min (at 4000 ppm) or less. The optimum ozone concentration over large volumes was 90 ppm for 120 min in ambient conditions (24 °C and 60-75% relative humidity). (4) Conclusions: This study showed that the appropriate ozone concentration and exposure time eliminated heat-inactivated SARS-CoV-2 RNA from the surfaces of different widely used clinical and office supplies, decreasing their risk of transmission, and improving their reutilization. Ozone may provide an additional tool to control the spread of the COVID-19 pandemic.

Longitudinal monitoring of SARS-CoV-2 in wastewater using viral genetic markers and the estimation of unconfirmed COVID-19 cases

In this study, wastewater-based surveillance was carried out to establish the correlation between SARS-CoV-2 viral RNA concentrations in wastewater and the incidence of corona virus disease 2019 (COVID-19) from clinical testing. The influent wastewater of three major water reclamation facilities (WRFs) in Northern Nevada, serving a population of 390,750, was monitored for SARS-CoV-2 viral RNA gene markers, N1 and N2, from June 2020 through September 2021. A total of 614 samples were collected and analyzed. The SARS-CoV-2 concentrations in wastewater were observed to peak twice during the study period. A moderate correlation trend between coronavirus disease 2019 (COVID-19) incidence data from clinical testing and SARS-CoV-2 viral RNA concentrations in wastewater was observed (Spearman r = 0.533). This correlation improved when using weekly average SARS-CoV-2 marker concentrations of wastewater and clinical case data (Spearman r = 0.790), presumably by mitigating the inherent variability of the environmental dataset and the effects of clinical testing artifacts (e.g., reporting lags). The research also demonstrated the value of wastewater-based surveillance as an early warning signal for early detection of trends in COVID-19 incidence. This was accomplished by identifying that the reported clinical cases had a stronger correlation to SARS-CoV-2 wastewater monitoring data when they were estimated to lag 7-days behind the wastewater data. The results aided local decision makers in developing strategies to manage COVID-19 in the region and provide a framework for how wastewater-based surveillance can be applied across localities to enhance the public health monitoring of the ongoing pandemic.

Ozone for SARS-CoV-2 inactivation on surfaces and in liquid cell culture media

This study evaluated the inactivation of SARS-CoV-2, the virus responsible for COVID-19, by ozone using virus grown in cell culture media either dried on surfaces (plastic, glass, stainless steel, copper, and coupons of ambulance seat and floor) or suspended in liquid. Treatment in liquid reduced SARS-CoV-2 at a rate of 0.92 ± 0.11 log10-reduction per ozone CT dose(mg min/L); where CT is ozone concentration times exposure time. On surface, the synergistic effect of CT and relative humidity (RH) was key to virus inactivation; the rate varied from 0.01 to 0.27 log10-reduction per ozone CT value(g min/m3) as RH varied from 17% to 70%. Depletion of ozone by competitive reactions with the medium constituents, mass transfer limiting the penetration of ozone to the bulk of the medium, and occlusion of the virus in dried matrix were postulated as potential mechanisms that reduce ozone efficacy. RH70% was found plausible since it provided the highest disinfection rate while being below the critical RH that promotes mould growth in buildings. In conclusion, through careful choice of (CT, RH), gaseous ozone is effective against SARS-CoV-2 and our results are of significance to a growing field where ozone is applied to control the spread of COVID-19.

Spatial and temporal variability and data bias in wastewater surveillance of SARS-CoV-2 in a sewer system

The response to disease outbreaks, such as SARS-CoV-2, can be constrained by a limited ability to measure disease prevalence early at a localized level. Wastewater based epidemiology is a powerful tool identifying disease spread from pooled community sewer networks or at influent to wastewater treatment plants. However, this approach is often not applied at a granular level that permits detection of local hot spots. This study examines the spatial patterns of SARS-CoV-2 in sewage through a spatial sampling strategy across neighborhood-scale sewershed catchments. Sampling was conducted across the Reno-Sparks metropolitan area from November to mid-December of 2020. This research utilized local spatial autocorrelation tests to identify the evolution of statistically significant neighborhood hot spots in sewershed sub-catchments that were identified to lead waves of infection, with adjacent neighborhoods observed to lag with increasing viral RNA concentrations over subsequent dates. The correlations between the sub-catchments over the sampling period were also characterized using principal component analysis. Results identified distinct time series patterns, with sewersheds in the urban center, outlying suburban areas, and outlying urbanized districts generally following unique trends over the sampling period. Several demographic parameters were identified as having important gradients across these areas, namely population density, poverty levels, household income, and age. These results provide a more strategic approach to identify disease outbreaks at the neighborhood level and characterized how sampling site selection could be designed based on the spatial and demographic characteristics of neighborhoods.

Removal of SARS-CoV-2 viral markers through a water reclamation facility

There have been multiple reports of COVID-19 virus, SARS-CoV-2 RNA presence in influent wastewater of water reclamation facilities (WRFs) across the world. In this study, the removal of SARS-CoV-2 RNA was investigated in a WRF by collecting samples from various stages relayed to hydraulic retention time (HRT) and analyzed for viral RNA (N1 and N2) gene markers and wastewater characteristics. SARS-CoV-2 RNA was detected in 28 out of 28 influent wastewater and primary effluent samples. Secondary effluent showed 4 out of 9 positive samples, and all tertiary and final effluent samples were below the detection limit for the viral markers. The reduction was significant (p value < 0.005, one-way analysis of variance [ANOVA] test) in secondary treatment, ranging from 1.4 to 2.0 log10 removal. Adjusted N1 viral marker had a positive correlation with total suspended solids, total Kjeldahl nitrogen, and ammonia concentrations (Spearman's ρ = 0.61, 0.67, and 0.53, respectively, p value < 0.05), while demonstrating a strongly negative correlation with HRT (Spearman's ρ = -0.58, p value < 0.01). PRACTITIONER POINTS: Viral RNA was present in all samples taken from influent and primary effluent of a WRF. SARS-CoV-2 gene marker was detected in secondary effluent in 4 out of 9 samples. Tertiary and final effluent samples tested nondetect for SARS-CoV-2 gene markers. Up to 0.5 and 2.0 log10 virus removal values were achieved by primary and secondary treatment, respectively.

Disinfection methods against SARS-CoV-2: a systematic review

Background

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the causative agent of coronavirus disease 2019, has caused millions of deaths worldwide. The virus is transmitted by inhalation of infectious particles suspended in the air, direct deposition on mucous membranes and indirect contact via contaminated surfaces. Disinfection methods that can halt such transmission are important in this pandemic and in future viral infections.

Aim

To highlight the efficacy of several disinfection methods against SARS-CoV-2 based on up-to-date evidence found in the literature.

Methods

Two databases were searched to identify studies that assessed disinfection methods used against SARS-CoV-2. In total, 1229 studies were identified and 60 of these were included in this review. Quality assessment was evaluated by the Office of Health Assessment and Translation's risk-of-bias tool.

Findings

Twenty-eight studies investigated disinfection methods on environmental surfaces, 16 studies investigated disinfection methods on biological surfaces, four studies investigated disinfection methods for airborne coronavirus, and 16 studies investigated methods used to recondition personal protective equipment (PPE).

Conclusions

Several household and hospital disinfection agents and ultraviolet-C (UV-C) irradiation were effective for inactivation of SARS-CoV-2 on environmental surfaces. Formulations containing povidone-iodine can provide virucidal action on the skin and mucous membranes. In the case of hand hygiene, typical soap bars and alcohols can inactivate SARS-CoV-2. Air filtration systems incorporated with materials that possess catalytic properties, UV-C devices and heating systems can reduce airborne viral particles effectively. The decontamination of PPE can be conducted safely by heat and ozone treatment.

Ozone Treatment Is Insufficient to Inactivate SARS-CoV-2 Surrogate under Field Conditions

COVID-19 caused by SARS-CoV-2 caused a worldwide crisis, highlighting the importance of preventive measures in infectious diseases control. SARS-CoV-2 can remain infectious on surfaces for up to several weeks; therefore, proper disinfection is required to mitigate the risk of indirect virus spreading. Gaseous ozone treatment has received particular attention as an easily accessible disinfection tool. In this study, we evaluated the virucidal effectiveness of gaseous ozone treatment (>7.3 ppm, 2 h) on murine hepatitis virus (MHV)-contaminated stainless-steel surface and PBS-suspended virus under field conditions at ambient (21.8%) and high (49.8-54.2%) relative humidity. Surficial virus was soiled with 0.3 g/L of BSA. Parallelly, a half-hour vaporization with 7.3% hydrogen peroxide was performed on contaminated carriers. The obtained results showed that gaseous ozone, whilst quite effective against suspended virus, was insufficient in sanitizing coronavirus contaminated surfaces, especially under low RH. Increased humidity created more favorable conditions for MHV inactivation, resulting in 2.1 log titre reduction. Vaporization with 7.3% hydrogen peroxide presented much better virucidal performance than ozonation in a similar experimental setup, indicating that its application may be more advantageous regarding gaseous disinfection of surfaces contaminated with other coronaviruses, including SARS-CoV-2.

Impact of sampling and storage stress on the recovery of airborne SARS-CoV-2 virus surrogate captured by filtration

Environmental air sampling of the SARS-CoV-2 virus in occupational and community settings is pertinent to reduce and monitor the spread of the COVID pandemic. However, there is a general lack of standardized procedures for airborne virus sampling and limited knowledge of how sampling and storage stress impact the recovery of captured airborne viruses. Since filtration is one of the commonly used methods to capture airborne viruses, this study analyzed the effect of sampling and storage stress on SARS-CoV-2 surrogate virus (human coronavirus OC43, or HCoV-OC43) captured by filters. HCoV-OC43, a simulant of the SARS-CoV-2, was aerosolized and captured by PTFE-laminated filters. The impact of sampling stress was evaluated by comparing the RNA yields recovered when sampled at 3 L/min and 10 L/min and for 10 min and 60 min; in one set of experiments, additional stress was added by passing clean air through filters with the virus for 1, 5, and 15 hr. The impact of storage stress was designed to examine RNA recovery from filters at room temperature (25 °C) and refrigerated conditions (4 °C) for up to 1 week of storage. To our knowledge, this is the first report on using HCoV-OC43 aerosol in air sampling experiments, and the mode diameter of the virus aerosolized from the growth medium was 40-60 nm as determined by SMPS + CPC system (TSI Inc.) and MiniWRAS (Grimm Inc.) measurements. No significant difference was found in virus recovery between the two sampling flow rates and different sampling times (p > 0.05). However, storage at room temperature (25 °C) yielded ∼2x less RNA than immediate processing and storage at refrigerated conditions (4 °C). Therefore, it is recommended to store filter samples with viruses at 4 °C up to 1 week if the immediate analysis is not feasible. Although the laminated PTFE filter used in this work purposefully does not include a non-PTFE backing, the general recommendations for handling and storing filter samples with viral particles are likely to apply to other filter types.