The theory of Ozone Disinfection
Is Ozone disinfection a valid method against Coronavirus? In these days we’ve received several questions similar to this one. We’ve tried to gather information about it from reliable sources and we’ve summarized them in the following article.
Many companies working in the zone disinfection field quote the Ministry of Health (protocol n° 24482 of 31/07/1996). According this document ozone has a good capacity to inactivate viruses. But no coronavirus is mentioned in this document.
It should be noted that in general humans can tolerate limited exposure to ozone. Beyond these limits, symptoms such as dryness of the mucous membranes, coughing, migraine and ribcage restriction may occur, and with higher concentrations even death. Concentrations above 50 ppm associated with exposures of more than 30 minutes are considered lethal.
A later document from 2010 (attached at the bottom of the page) shows that the treatment should be at concentrations of around 4 ppm for 20 minutes. This is well above the hazard threshold of 0.3 ppm for 15 minutes.
Here More information about risks associated with ozone.
So the first advice we would like to give you is: always consider the ozone concentration generated and avoid people presence of people being present in the treatment area.
If you hire an external company, make sure they are able to measure and document the ozone concentration, to give evidence of the effectiveness of the treatment. And first of all to avoid dangerous exposures to people and property.
According to H.A.C.C.P. and D.Lgs. 626/94, the user must not be exposed to more than 0.1 ppm ozone in 8 hours or more than 0.3 Is ozone really recognised as a method of inactivating the coronavirus?
Ozone Disinfection: Can ozone really inactivate the coronavirus?
First of all, ozone is a molecule made up of three oxygen atoms, which is very reactive and unstable and could be capable of inactivating a protein membrane virus such as the coronavirus (SARS-CoV-2).
We have already observed that ozone is a toxic gas, that it can cause discomfort if inhaled in sufficient quantities, and that these levels are very close if not lower than the concentrations required for effective treatment.
What are the concentrations and contact times needed to achieve the desired result? Official voices, such as those of the ISS, have reiterated that no experiments have been carried out in this regard, and all the officially published guidelines speak of three active ingredients capable of inactivating the virus, and ozone is not one of them. The official documents are attached at the bottom of this page.
We would like to mention the recommendations for the disinfection of outdoor areas and surfaces, recently published by the ISS
According to ECDC and WHO guidelines, it is recommended: for disinfecting hard surfaces the use of 0.1% sodium hypochlorite after cleaning with water and neutral detergent (pH neutral).
For surfaces that could be damaged by sodium hypochlorite, ethanol (ethyl alcohol) 70%, v/v can be used as an alternative, always after cleaning with water and a pH-neutral detergent.
Ozone Disinfection: IOA Opinion (International Ozone Association)
Basically, the International Ozone Association affirms that until there are no scientifically approved studies, it is not possible to talk about the inactivation of SARS-CoV-2. Below is a screenshot of the original document:
Ozone Disinfection: Our opinion
There is therefore no overwhelming reason for us to recommend ozone for COVID disinfection.
As the effectiveness is to be proven and there are also risks for people, when instead there are effective products that are much less harmful. Not to be overlooked is the reactive effect of ozone on things.
Furthermore, detecting the correct concentration of ozone is not easy and requires specific instruments. if the concentration is too low, the treatment may be useless, or if the it’s too high it could be potentially harmful.
Especially for working environments, our suggestion is to use officially recognised products.
The officially recognised disinfectants against Sars-CoV-2 are:
- hydrogen peroxide
- sodium hypochlorite
- alcoholic solutions (preferably 70%)
Instead Ozone we recommend ultrasonic nebulizers.