Asked if he was surprised to hear Mr Donnelly say the expert advice he had received states that there is not a role for these air filters in school, Prof Wenger said: “Our group was appointed specifically to provide advice on ventilation and related measures like filtration.”

Prof Orla Hegarty argues that proper ventilation of buildings to ensure a constant supply of clear air, in addition to proper masking protocols, is the most effective way to suppress the spread of the virus.