Video report by ITV Wales reporter Hamish Auskerry
Plans to provide schools in Wales with ozone machines that disinfect classrooms have been scrapped, the Welsh Government has confirmed.
The machines, developed by Swansea University, emit a toxic gas that the university said was very effective at removing Covid.
But a review of the machines found they could cause 'harm to human health'.
The Welsh Government announced last month the plan to spend £3.31m on 1,800 ozone disinfecting machines to disinfect schools and reduce the spread of Covid-19.
Plaid Cymru raised questions about the safety of the toxic chemicals contained within the technology.
A Technical Advisory Group review concluded the proposed ozone machines are not suitable for use in education settings.
The review warned the gas ozone, which can be used as a disinfectant, "is a highly harmful indoor pollutant."
It found children with underlying respiratory conditions were "particularly sensitive to ozone exposure" and the deployment of ozone to educational settings would require 'substantial resources' to ensure their safety.
Opposition parties accused welsh ministers of a 'u-turn' when the Welsh Government said that it would wait for its Technical Advisory Group to review the machines and 'provide further advice on their use within education settings', before implementing them.
In a statement, Swansea University defended the machines, saying they "were extensively tested in a variety of school settings."
A spokesperson said: “Ozone is already being used effectively as a disinfectant in a range of settings and our involvement has been to provide the research and development behind ozone machines."
"The machines reduce the contact of users with Covid-contaminated environments and must always be used according to strict safety guidelines.”
What are CO2 monitors?
CO2 'Traffic light' monitors are due to be provided to classrooms, seminar rooms and lecture halls in Wales, with the rollout expected to be completed by mid-November.
The new CO2 monitors which include sensors will notify teachers and lecturers when CO2 levels rise, so they can identify where ventilation needs to be improved.
This will help maintain comfortable temperatures for learners and staff during colder periods, reduce heat loss and save on energy costs, according to the Welsh Government.
Where the monitors identify a recurring CO2 issue, schools, colleges and universities will be able to access funding from the Welsh Government to undertake improvement works.
The Welsh Government has now unveiled plans to spend the money on CO2 monitors and improving ventilation in schools.
Minister for Education and Welsh Language Jeremy Miles said: "This investment for ventilation improvements, along with the rollout of CO2 monitors, will help to keep transmission rates low.
"However, it is still really important that we all do our bit to reduce the spread of Covid-19, and this includes regular handwashing and maintaining distance where we can."
Welsh Conservative Shadow Minister for Education, Laura Anne Jones MS welcomed the move and added: "This was another Labour policy that was sadly not thought through in the chase for a cheap press headline.”
David Evans, Wales Secretary for the National Education Union Cymru says the NEU is 'pleased' to see the investment towards ventilating Wales' education settings.
"Everyone wants education to return to normal, but whilst the pandemic is still with us, mitigations in education settings are necessary to keep staff and students safe."
Unions have been calling for ventilation to ensure schools, colleges and universities can remain open over the winter for as long as possible.
"We look forward to learning how schools and colleges will easily access this funding. It is absolutely vital that any work needed to improve ventilation is undertaken as quickly as possible," Mr Evans added.
"We note that in Scotland, the local authorities have been tasked with auditing ventilation in education settings, which seems a sensible approach. We look forward to more details from the Welsh Government."