Professor Gabriel Scally also said staff working at an education maintenance helpline are unlikely to have the expertise required to carry out effective assessments of ventilation in schools.

Instead, he said on-site inspections should be carried out by ventilation engineers and results of how effective ventilation is in a classroom should be freely available to parents.

Prof Scally, a member of independent Sage, has also blasted as “ridiculous” the stance taken by the education minister not to roll out air filtration systems to classrooms across Northern Ireland.

It comes after Michelle McIlveen said “the scientific evidence regarding the effectiveness of air cleaners is inconclusive”.

The DUP minister also revealed it could cost £40m to install them in 20,000 classrooms across the school estate.

However, Prof Scally pointed to a research study from the Centers of Disease Control and Prevention (CDC) in the US, which he described as “the most authoritative public health agency in the world”.

The CDC study, published in July 2021, found using two HEPA air filters close to an infected person reduced aerosol exposure by up to 65%.

A combination of HEPA air cleaners and universal masking reduced exposure by up to 90%, said the study, which concluded “portable HEPA air cleaners can reduce exposure to simulated SARS-CoV-2 aerosols in indoor environments, especially if combined with universal masking”.

“It seems to me the Department of Education has done nothing to make schools safer since the start of the pandemic,” said Prof Scally.

“The problem is the politicians are looking at each measure individually rather than how air filtration systems work in combination with other measures.”

A Department of Education spokesman said: “The most effective mitigating measure in relation to Covid-19 is natural ventilation and the Department and the Education Authority will continue to support schools in prioritising the effective implementation of this measure.

“Air cleaning units are not required in every classroom and to install them would cost around £40m.

"Ventilation will mainly be an issue in smaller windowless rooms or where there are issues with windows. Air cleaners should never be used as a substitute for ventilation.