Testing for asbestos at Bayfield School in Auckland has found no sign of the dust in areas accessible to children and staff, the Ministry of Education says.
Parents from the decile 10 Bayfield School were on Wednesday night sent an email saying the school would be closed until further notice.
The email said tests had indicated the possibility of asbestos from a building which was being demolished, and further testing was being carried out on Thursday.
Ministry of Education infrastructure service head Kim Shannon said it was reassured by results which showed no sign of dust in areas accessible to children and staff but that more testing would be done.
As well as a WorkSafe investigation, the ministry would investigate how the demolition site was managed.
Ms Shannon said Worksafe New Zealand has developed a plan to remove remaining demolition materials from the school.
Brett Archer, who runs a construction management company, has two children at the school.
He said he became worried when his wife was covered in dust after dropping off the children on Tuesday.
Mr Archer kept them home from school on Wednesday and said he carried out testing which revealed asbestos cladding outside the demolition cordon and asbestos dust on classrooms.
"I am worried ... the evidence would suggest that kids seem to be more susceptible to asbestosis or dust or issues from asbestos," Mr Archer said.
The school will be closed on Friday.