Development of an ozone-based disinfection process for highly efficient inactivation of SARS-CoV-2

Coronavirus-2019 disease (COVID-19) is caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the mode of transmission of which is primarily through respiratory droplets and aerosols. Based on studies, the SARS-CoV-2 virus lodges and survives on non-porous surfaces, such as plastic, for up to 28 days. SARS-CoV-2 was also recovered from the outer layer of surgical masks after seven days.

Study: SARS-CoV2 neutralizing ozone activity on porous and non-porous materials. Image Credit: Invisible Eye / Shutterstock

The use of personal protective equipment (PPE) is an integral part of protecting against the transmission of SARS-CoV-2. However, the sudden increase in demand for masks during the COVID-19 pandemic, due to widespread use, has resulted in critical supply delays and massive volumes of waste generation. Therefore, the design of an easy to use and durable disinfection technique has become necessary.

Traditional methods have certain drawbacks in sterilizing PPE. The ozone disinfection technique is an efficient, fast, economical and environmentally friendly alternative. The antimicrobial and antiviral activity of ozone has been shown to be effective in eradicating a wide range of bacterial targets, as well as enveloped and non-enveloped viruses. Targets for ozone disinfection include the viral capsid, specific viral binding epitopes, and viral DNA / RNA.

Ozone disinfection has been reported to effectively disinfect an N95 respirator for Pseudomonas aeruginosa – a sporulated organism with high resistance to disinfection processes. This report confirmed that ten cycles of ozone disinfection did not confer significant changes in the filtering capacity of the respirator.

SARS-CoV-2 is likely to be more sensitive to ozone disinfection than the other species tested. Ozone disinfection has demonstrated remarkable viral inactivating activity when used for various metal surfaces contaminated with corona pseudovirus and human coronavirus 229E (HCoV-229E). In addition, ozone helps eliminate unpleasant odors.

The study

This study, published in the journal New biotechnology, aimed to assess the ozone capacity generated in a newly developed disinfection chamber to eradicate SARS-CoV-2 from porous materials like cotton and filtering face masks 3 (FFP3) and non-porous materials like glass.

Researchers have developed an experimental device called the disinfection chamber. The prototype included an aluminum chamber with a capacity of 1450 ml containing a patented plasma generator based on direct piezoelectric discharge (PDD). In addition, it incorporated a microcontroller to regulate the disinfection process.

Here, virus-contaminated matrices were positioned on the metal sample holder in the disinfection chamber, closed with a screw cap on top. The plasma generator produces cold plasma inside the disinfection chamber and ozone is generated as a by-product. The application has been tested on porous and non-porous materials.

Data analysis has been performed. Statistical differences were determined between the control group and the experimental group. Viral copy numbers based on RT-qPCR cq values ​​were calculated using a calibration curve based on a certified RNA standard.

The ozone disinfection process inside the disinfection chamber is divided into phases of generation (phase 1) and chemical decomposition (phase 2). In phase 1, there is an exponential increase in ozone concentration over time. After that, the cold plasma source is stopped and the disinfection chamber remains closed, which marks the start of phase 2.

In this study, five minute ozone generation was performed for all surfaces tested, resulting in a maximum concentration of 800 ppm inside the chamber. For FFP3 and cotton face, there was an additional five minute exposure, which led to ozone decomposition at 750 ppm. An additional 55 minute exposure was allowed on glass surfaces which decomposed to 400 ppm.

Conclusion

The results concluded that a highly efficient combined heat drying and ozone treatment process is suitable for disinfecting various porous and non-porous surfaces contaminated with SARS-CoV-2.

Ozone treatment has shown a reduction in the virus. This could make masks reusable, help overcome mask shortages, and significantly reduce waste generated by disposing of PPE. This technique can also have industrial applications and can be used for domestic utilities.