The efficacy, effectiveness and safety of SARS-CoV-2 disinfection methods (including ozone machines) in educational settings for children and young people

How safe and effective are methods of disinfection for COVID-19 used in schools and colleges for children and young people?

There are several ways of disinfecting air or surfaces in educational settings. These can use a type of light, moist gas (hydrogen peroxide) or dry gas (ozone). It is important to find out how well these work in reducing the spread of the virus and whether or not they create any health risks to the pupils.

The results on how effective these methods were showed that:

• Pieces of virus could be found on treated surfaces seven days after cleaning, but it was not known if these could still cause an infection.
• Ozone, light or hydrogen peroxide gas could inactivate the virus in laboratory experiments, but this was not proved in real world settings.
• If a person with COVID -19 has been in a room and left, there was a very low risk of anyone catching the virus 72 hours later.  This was true whether or not the room has been cleaned.

Safety issues related to ozone were of great concern. Results showed that:

• Short term exposure to ozone at very low levels could cause respiratory health problems. Children with asthma were more at risk.
• Ozone gas is very toxic at high concentrations. Rooms using ozone machines need to be sealed off to avoid leakage of the ozone gas.
• Ozone may react with other materials to form other chemical dangerous to health.

Concerns also existed about safe removal of ozone after cleaning, measuring exposure of pupils to the gas and staff training to use the disinfectant.  Two reliable safety bodies have stated that ozone is not currently recommended for air cleaning until its safe use can be proven.

In summary, there is a lack of evidence that ozone is an effective and safe disinfectant.  There is positive evidence that ozone is harmful for health of children and young people. Together, these mean that it cannot currently be recommended as a disinfectant in schools and colleges.

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