Some principals doubt they can properly and adequately ventilate their classrooms to reduce the spread of Covid-19 during winter.
They say leaving doors and windows open is not practical on cold days and the 5000 air purifiers the Education Ministry is providing won't be enough for the country's 2400 schools.
They say their best hope of containing the virus will be continued use of face-masks.
RNZ education correspondent John Gerritsen reports.
