Students have been kept of Bromley Primary School grounds for a third day because a mystery smell can't be ruled out as dangerous.
Principal Scot Kinley posted on the school's Facebook page saying "the origin and type of gas has yet to be identified or whether there are any associated health risks", he says. "I feel by closing Friday and then having the weekend there is a high probability that the air will be clear by Monday or the issue identified."
He says the smell had decreased but was still evident in some places.
Environment Canterbury thought the cause may have come from a pile of dirt dumped in the Maces Rd area.
ECan have been using meterological software to track which direction the smell could have been coming from as well as conducting air tests and visiting sites.
The green lines track potential paths
Emergency services were first called to the school, on the east of the city, on Wednesday. They gave the students the all clear at 10:15am but students stayed inside as a precaution until 12.50pm. They gas smell returned in pockets around 1:30pm and became stronger in certain areas after 2pm.
ECan believes the smell is no risk to the school and the school could reopen.
The fire service were called eight times in the past 48 hours, while ECan has had almost 20 phone calls about the mystery smell in the surrounding areas of Wainoni, Dallington, Bexley.
ECan gets about 6000 calls a year about bad or strange smells.