Hon CHRIS HIPKINS: It is important to recognise that most schools do not have artificial ventilation systems; they have windows and doors. They don't have air conditioning, they don't have ducted air ventilation, and it is through ducted air ventilation that HEPA filters are used. So, in most cases, the best way of ventilating those spaces is going to be to have the windows and doors open. Where it's not possible to open the windows and doors or where ventilation opportunities are very poor, or where there are structural ventilation systems, we'll work with schools on a case by case basis to identify what's best for their needs. 