The  word virus comes from the Latin virus which means poisonous fluid or toxin. According to the National Institute of Health: “A virus is an infectious agent. It is a particle much smaller than a bacterial cell, consisting of a small genome of DNA or RNA surrounded by a layer of protein. Viruses enter host cells and take over host cell enzymes and materials to make more copies of themselves.

Viruses cause a wide variety of diseases in plants and animals, including HIV, measles, smallpox, and polio and, of course, the various mutations of co-virus, including SARS-CoV-2.

Viruses can enter the body through the nose, mouth or skin lesions. Different viruses infect different cell types based on the virus’s ability to recognize the type of host cell and successfully enter cells. Once inside (infection), the virus genome is activated to produce the repeating proteins needed to create new virus particles and the cycle is repeated. For example, flu and cold viruses attack cells that line the respiratory or digestive tract. Norovirus, for example, invades the gastrointestinal tract. SARS-CoV-2 attacks cells in the lungs and bronchi.

Viruses can remain active on different surfaces for different periods of time, depending on the virus, the type of surface and the environment. Cold viruses can remain active on surfaces for up to a week, while influenza viruses can survive for about 24 hours, and SARS-CoV-2 virus remains active for approximately 72 hours. During this period, the virus lodges on surfaces, waiting to be carried by a host.

An important note, viruses do not kill themselves, they are inactivated. Because, as already mentioned, viruses are not living organisms – they are not made of cells, they cannot reproduce without invading a host cell, they do not respond to environmental stimuli and they have no metabolism. Since a virus is not “alive”, it cannot be “killed”. In medicine, medical references to dead viruses refer to a technique in which viruses are chemically or mechanically inactivated, so that they can be used in the production of vaccines or in research without the possibility of causing infection or, in our case, disinfecting a surface or space. It is in this sense that we use the term “inactivation”, where we apply ozone to chemically treat a virus, so that it cannot infect living cells.

According to some of the most experienced doctors on ozone and viruses, such as Dr. Gérard Sunnen (a physician in New York, specialized in the use of ozone in the medical field, from cutting-edge ozone therapy to the use of ozone as a disinfectant), “Ozone has unique disinfectant properties. As a gas, it has a penetration capacity that liquids do not. In addition to the fact that previous strains of SARS-CoV-2, MERS (Middle East Respiratory Syndrome) and SARS (Severe Acute Respiratory Syndrome) persist for several days on surfaces, it is suggested that ozone be applied in the decontamination of medical environments and others”.

According to a study published in the Journal of Hospital Infection, on 2020 January 31^st, it concluded that Covid-19 can survive between hours to days on different surfaces, which have been touched by infected patients, thus remaining a contagion focus. For example, in aluminum, at a temperature of 21ºC, the new coronavirus resists up to eight hours; PVC or ceramic (tiles) persists for up to five days; in the role of a book, at room temperature, the virus can survive between four to five days; in plastic (or objects of this material), at a temperature of 21ºC to 25ºC, the virus resists up to five days; in glass or wood, can last up to four days and in metal up to five days.

Knowing that something works is not enough; so, let’s see how ozone works in virus inactivation. “Typically, viruses are small independent particles, made up of crystals and macromolecules. Unlike bacteria, these particles multiply only within the host cell. Ozone destroys viruses, diffusing through the protein coating to the nucleic acid nucleus, causing damage to viral RNA. At higher concentrations, ozone destroys the capsid or the outer layer of the protein by oxidation” explains Dr. Sunnen. In addition, “most research efforts on the viricidal effects of ozone are focused on ozone’s propensity to separate lipid molecules at multiple link configurations. In fact, once the virus’ lipid envelope is fragmented, its DNA or RNA nucleus cannot survive”.

According to the opinion of the director of the Center for Disease Prevention and Control (CDC) in Georgia, USA, Dr. Paul Meechan, regarding ozone as a viricide, especially regarding SARS-CoV-2, “ozone works, it is very effective in inactivating viruses, especially in enveloped viruses such as SARS-CoV-2. Ozone solubilizes the lipid membrane of the virus in just a few seconds. Ozone will disable SARS-CoV-2, but you need to know what you are doing.

The term log reduction means the reduction of microorganisms to a safe level. Logarithmic reduction is a mathematical term used to express the relative number of live microbes or active viruses that are eliminated by disinfection and corresponds to the inactivation of 90% of a target microbe with the microbial count reduced by a factor of 10. Thus, a reduction 2 log will exhibit a 99% reduction or reduction of microbes by a factor of 100 and so on. The table shown shows the log reduction graph.

The ozone concentration and exposure time vary depending on the target virus. Considering the structure of SARS-CoV-2 and how viruses respond to ozone exposure, it is estimated that just 1 ppm of concentration for just a few seconds is enough to reach up to 4 disinfection logs. A good quality ozone generator can achieve this concentration in a short period of time.

Ozone level production is essential; generators are classified by the ozone weight they produce per hour (g / h). To test the time required to reach 1 ppm of concentration, using a generator that produces an output of 16 g / h ozone, in a space of 28 m³, at 18 ° C and with a relative humidity of 14%, the generator reaches 0.5 ppm in 15 seconds and 1 ppm in <2 minutes. The ozone production rate decreases as ozone generators convert ambient oxygen into ozone, that is, the production rate decreases as the concentration increases, resulting from a continuous reduction in the number of O2 molecules available in space closed. Therefore, the peak ozone production depends directly on the generator power, as smaller systems can stabilize at a lower ozone concentration. High-powered ozone generators also have the benefit of obtaining effective concentrations quickly, which allows for greater utility and overall benefit.

It is proven, both in the laboratory and in the field, that ozone is an extremely effective viricide and has a full spectrum antimicrobial action, killing pathogenic bacteria and fungi, in addition to the countless benefits it offers as disinfection alternatives.

Because it is a gas, it has a penetration capacity that liquids do not. An ozone generator never needs to be recharged with consumables or solutions and does not need to be operated manually, just program the timer and press the button. Ozone generators make it possible to transform the oxygen present in ambient air into powerful and oxidizing ozone. At the end of the disinfection, plus the ozone stabilization time (and its conversion to oxygen), it can re-enter the space as the disinfection is complete.

Ozone is an extremely strong oxidizer, an excellent disinfectant and with an ideal free chemical purification, which gives ozone a strong effect on pathogens.

According to the statement issued by the Portuguese Society of Ozone therapy on July 20, 2020, “Ozone therapy is the set of techniques that uses ozone as a therapeutic agent in a large number of pathologies. (…) Regarding the reaction of ozone to COVID-19, we can use ozone through the use of ozonized water, through nebulizers and by air (gas), this is where we need to take some precautions because the pathway epithelium Respiratory systems have no enzymes and are not prepared to react with ozone, which can damage the respiratory mucosa, so the concentration of gaseous ozone in the air cannot exceed 2ppms to breathe, complying with international regulations, OSHA standards. However, ensuring the dissipation of ozone in the air (ozone has a maximum duration of 30 minutes) is an excellent option for disinfecting spaces and surfaces. In terms of nebulization, the use of moisture created from ozonized water with a high oxidative content ends up eliminating viruses and bacteria without checking the risks of inhaling gaseous ozone, thus disinfecting the contact surface without any side effects or risks for the health. Being a recommendation, even, the intake of ozonized water. ”

According to the article originally published in May 2013 published by the American doctor, Dr. Gérard V. Sunnen, under the title “Emerging MERS, SARS and Coronavirus: Theoretical Considerations and a Proposal for Parenteral Oxygen / Ozone Therapy for Critical Care – This article has been updated to reflect the worldwide appearance of Covid-19. (…) Ozone, due to its biological properties, has theoretical and practical attributes to make it a viral load selection agent Covid-19, MERS and SARS. The key to this strategy is incorporated in the coronaviral vulnerability to oxidizing agents due to the fragility of its lipid-rich envelopes. ”