SNP ministers plan to spend £300,000 chopping the bottoms off hundreds of classroom doors to try to stop the spread of Covid in schools.

Shirley Anne-Somerville, the Scottish Education Secretary, wrote to MSPs informing them that around 2,000 doors could be “undercut to increase airflow”.

In a letter to Holyrood’s education committee, she said between two and four per cent of rooms across Scotland’s schools and nurseries had been identified as having “problematic” carbon dioxide levels because of inadequate ventilation.

She said this was the equivalent of around 2,000 classrooms and £5 million would now be spent trying to improve their airflow using filtration units, extraction fans and by chopping off the bottoms of doors.

Each door is expected to cost around £150 to rectify, she said, resulting in a total cost to the public purse of around £300,000.

But Willie Rennie, the former Scottish Liberal Democrat leader, attacked the SNP for only acting to improve ventilation nearly two years after the pandemic had started and argued that schools deserved a “better solution” than having their doors shortened.

The move emerged the day after Nicola Sturgeon refused again to allow secondary pupils to remove face masks in classrooms, claiming the change was still premature despite it being made in England on January 20.

Scotland’s pupils are being forced to endure “very cold” classrooms with windows being kept wide open for the second winter running, teachers warned last month.

Scottish Teachers for Positive Change and Wellbeing (STPCW) said it was “unfathomable” that two years into the pandemic pupils were still being asked to layer up with warm clothing because of the temperature in classrooms.

The group complained it had received no response from SNP ministers after writing to them expressing their concerns and argued it was “shocking” that air filtration systems were not being bought, despite orders being placed in England.

In her letter, Ms Somerville set out a list of three potential “remedial measures” for problem classrooms and the cost of each.

Air cleaning and filtration units costing £1.6 million are to be installed as a “temporary” measure, with a further £2.4 million on extractor fan units as a “longer-term solution”.

She added: “Finally, we have assumed the door in the example space will need to be undercut to increase airflow, at a cost of £150, in line with business ventilation fund guidance.”

Facemasks likely to remain for weeks

But Mr Rennie said: “Rather than putting an air filter in every classroom, the Education Secretary’s solution is sending a handyman round to chop up classroom doors.

“We are two years into the pandemic and three terms into this school year but only now has the Scottish Government admitted there is a problem in thousands of classrooms. Yet this could only be the tip of the iceberg.”

He added: “Opening windows in winter and chopping up doors is an insult to the thousands of teachers and pupils who deserve a better solution to the problems of ventilation.”

Meghan Gallacher, the Scottish Tories’ Shadow Children’s Minister, said: “If this issue wasn’t so serious, you’d be hard pressed not to laugh at this crackpot SNP proposal.

“Is sawing off the bottom of classroom doors seriously Scottish Government policy to tackle the ventilation problem in classrooms?”

But Ms Sturgeon said: “Having adequate spaces under doors is an important way of improving airflow in some spaces where perhaps that is one of the rectifications that is needed.

“It’s not the only way, so air filtration systems on a temporary basis, mechanical ventilation systems – all of these are important to improving ventilation and air flow in classrooms.”

Ms Sturgeon told MSPs on Tuesday it was now “close to the time” when face coverings would not need to be worn in classrooms, but her advisors had stopped short of recommending the change be made immediately.

They will reconsider the issue at a meeting next Tuesday but it is likely to be weeks before any change is implemented.