Why the Welsh government is wrong to use dangerous disinfection machines in schools



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Bethany Powell, left, is helped by Sarah Wheelwright, school age coordinator, to pin a pattern at the Youth Center April 9, 2020, at Hill Air Force Base, Utah. Children at the center set out to create masks for themselves and for caregivers at Hill AFB’s Youth and Child Development Centers. (U.S. Air Force photo by Todd Cromar)

Dr Eilir Hughes

The announcement that the Welsh government would spend nearly £ 6million on technology for schools to reduce the risk of transmission of Covid-19 came with joy and alarm in equal measure.

As a supporter of measures to mitigate the risk of airborne transmission of Covid-19, which was largely ignored during the pandemic, I was happy to learn that carbon dioxide (CO2) monitoring would finally reach schools all over Wales.

What do I mean by each corner? Well, since the start of the year, in partnership with Menter Môn, a corporate agency that offers a range of innovative projects, CO2 monitors have been provided to schools, nursing homes and office spaces under the responsibility Anglesey Council.

It was a breakthrough after months of campaigning alongside materials scientist Dr Huw Waters under the #FreshAirWales banner.

The campaign grew out of ever-growing frustration that awareness of the aerial spread of the virus was not reaching the ears of the Welsh public. So, over the August 2020 bank holiday weekend, we published a bilingual website (www.freshair.wales) which explained how the virus is transmitted via small airborne particles and how better ventilation could help limit the spread.

We discussed how CO2 monitors could be used to ensure adequate ventilation. They work on the principle that the increase in CO2 levels in the air due to the exhalation of the breath is an indicator of poor ventilation. If the readings are low, ventilation is likely to be good. If it’s high, you’d better open that window quickly.

Since mid-December 2020, the Welsh government has recognized the benefits of fresh air, stating that: “Leaving fresh air indoors can reduce the risk of coronavirus infection by 70%.”

Welsh Health Minister Eluned Morgan was absolutely right in advising people to spend their August bank holiday weekend outdoors as much as possible, where the risk of transmission is said to be 20 times lower than indoors .

A year later, in early August 2021, Scottish Prime Minister Nicola Sturgeon announced that all schools and childcare centers in Scotland must have access to CO2 monitors.

A few weeks later, the UK government announced a £ 25million fund to equip all UK public schools with CO2 monitors.

My response to this was a joy, followed by little trepidation. Will Welsh schoolchildren and teachers miss out on the benefits of this technology?

Fortunately, with today’s announcement, colleges and universities in Wales will also get £ 2.58million to purchase 30,000 monitors. I have no doubt this will prove useful to teachers as they kick off the new school year in a week’s time.

“Ozone disinfection machines”

However, in addition to the monitors, a larger sum of £ 3.31million is spent on 1,800 ‘ozone disinfection machines’.

Their introduction into the arsenal of the education system to combat transmission follows comments to the government by schools expressing difficulties and increasing expenditure in an attempt to meet current expectations for deep cleaning following epidemics. of Covid-19 infections.

By turning to technology more familiar to slaughterhouses than to classrooms, the Welsh government is willing to use the extra money to make us feel safer, but is doing little to reduce the risk.

So how do ozone cleaners work?

They convert oxygen atoms into ozone which easily reacts with other substances it encounters. Their potential use has been praised by many who claim they could be useful as air purifiers to fight the virus.

The intention is to disinfect teaching environments when they are not occupied. Researchers from Swansea University who are funded to build these machines say: “Ozone is powerful against the Covid-19 virus and due to its gaseous nature it kills the virus, whether it is suspended in air or adheres to a surface. “

But concerns about the apparent weakness of such claims prompted the United States Environmental Protection Agency (EPA) to release a report that I can’t help but compare to the marketing of oil from snake in nineteenth century America.


Ozone is considered a toxic substance. EPA refers to the well-known risk to human health from exposure to ozone.

He says, “When inhaled, ozone can damage the lungs. Relatively small amounts can cause chest pain, coughing, shortness of breath, and throat irritation. Ozone can also worsen chronic respiratory diseases such as asthma and compromise the body’s ability to fight respiratory infections.

It is important to note that these machines will not be used when occupied by teachers or learners due to potential health risks. But someone will have to make them work, probably an employee of the local authority or the university.

Using ozone to disinfect seems counterintuitive. In an attempt to reduce the risk of harm to human health, we use toxic chemicals when safer alternatives are available.

And to suggest that disinfecting potentially infected air when no one is present to breathe it is an insult to our intelligence. Background air exchange occurs overnight, so efforts to sterilize the air are in vain. The next morning, a contagious person returns to class for the day, spends hours in the company of other people, and in doing so, the risk of infection persists.

Surfaces are highly likely to be disinfected, but the sterility of the room’s ledges or baseboards does not prevent one from contracting Covid-19.

The UK Health and Safety Executive has published guidelines on the use of disinfectants such as ozone.

It states that: “Upholstery can act as a ‘sink’ for airborne chemicals and emit them for some time after treatment (remove items such as sofas before treatment)”

They state that people should not enter rooms treated with such chemicals. The space in which this technology would be operated would have to be completely sealed, posing an additional challenge for schools and polluting the outdoor environment. As any science teacher would tell you, ground-level ozone is not nature’s friend.

The irony of all of this is that once the ozone gas is released into space, the environment has to be made safe again so that no residue is left when teachers and learners return.


Guess what they should use to do this? Yes, ventilation.

Fresh air helps remove disinfectant after treatment as long as ventilation can be controlled from outside the room. Another challenge for the school guard!

What is really surprising is that the adoption of ozone technology seems to go against the government’s own advisers. In a report titled ‘Air Purifying Devices’, the Welsh Government Technical Advisory Group (TAG) said that’ devices that use HEPA filters and germicidal ultraviolet (UV-C) light are better than purifiers using other technologies such as oxidation ‘ozone is one of them.

Thus, it seems clear that ozone should have no role to play in trying to reduce the risk of inhaling the virus. But its current use in other environments such as the food industry and healthcare is focused on surface disinfection.

However, we must ask ourselves if surface cleaning is worth more than half of the technological prevention funds in our educational establishments? Will sterile surfaces make a significant difference in the risk of transmission, or could money be better wiser?

For some time, the U.S. National Health Protection Agency, known as the Centers for Disease Control and Prevention (CDC), has called the possible risk of becoming infected through contact with surfaces or contaminated objects, called fomites, as being weak.

He states that: “There is little scientific support for the routine use of disinfectants in community settings, whether indoors or outdoors, to prevent the transmission of SARS-CoV-2 by vectors. liabilities “

He adds that when a confirmed case of covid-19 has been identified within 24 hours, high-contact surfaces should be disinfected, which fits well with the current role of the school’s household cleaner.

Instead of deploying expensive, untested, and unnecessary technology that could be damaging to the environment and dangerous to human health, I would say that we should focus our efforts on the interventions that provide the most benefit in terms of reducing harm. risks.

It should focus on what we know. Spending time with others outdoors offers a 20-fold reduction in transmission. If natural ventilation is provided for indoor environments, transmission is reduced by up to 70%.

There is no data to suggest that the use of surface disinfection equipment will reduce the transmission of SARS-CoV-2 in schools. Instead, substantial government funds should be redirected towards maximizing natural ventilation, and failing that, turn to air purification methods while classrooms and auditoriums are occupied, such as halls. high efficiency particle absorbing filters.

Remember, nothing beats bringing in some fresh air to make indoor environments safer.


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