Ally Enright loves bouncing on the trampoline, shooting basketball hoops and playing with her dog, but when the air reeks of the stench of Bromley's burnt-out wastewater treatment plant she hides in her bedroom.

Even then, the smell creeps in.

"I always just constantly get the smell in my room and it makes me feel sick and want to spew," she said.

Ally goes to Bromley School with Ezmae Campbell, who also holes up in her room when it stinks.

"I have to lock myself in my bedroom because of how smelly it smells," she said.

Council contractors are about to start removing the rot from inside the plant's trickling filters in a process that is expected to take four months, but parents and teachers are worried about their children's health and the worsening stench over winter.

Work has begun this week to resolve the smell of rotting material at the Christchurch Wastewater Treatment Plant (Photo: Screenshot/Christchurch City Council).

While the council insists there is no danger to public health, Bromley School teacher Cathy Baker carries a nagging concern.

"When the smell is at its worst we really worry about having the kids outside. We have a lot of kids with sore tummies. We don't know what this revolting smell is doing to our children's health," she said.

Bromley School pupil Amelia Piggin said the smell put her off lunch and made it hard to concentrate in class.

"I would usually pull my top over my nose and mouth, nose mainly, so then I can't smell it. It stops me from writing and doing work on my iPad because I can't really do it when I'm holding my t-shirt up," she said.

Sulphurous gases including one known as "swamp gas" were detected in specialist air quality tests around the plant last month.

The results detected small amounts of hydrogen sulphide and methyl mercaptan, but the council said they remained well within WorkSafe's exposure standards.

Mother of three Abbi Skyes said her children were suffering from headaches, especially after playing sport.

"As soon as they've had a little run around in it they're saying they're tired, they've got a headache, they need to go home," she said.

"We've been told it's under WorkSafe guidelines, but we're not working in it, we're living in it. For little lungs to be breathing that in, it makes me concerned."

Bromley School principal Scot Kinley has been trying to ventilate classrooms to reduce the risk of Covid infections and shut out the foul-smelling air at the same time.

He worries people are getting used to living with the stench.

"When you get used to it you stop taking precautions of fresh air and withdrawing from it and looking after yourself because you become almost acclimatised to it. I think that's a huge concern," he said.

"It must be playing havoc with people's mental health. This is a low socio-economic area, it was absolutely smashed in the earthquakes and then high rates of the Covid virus. It's not good enough, it has to be fixed."

A big crowd is expected at a public meeting in Bromley tonight, where Christchurch mayor Lianne Dalziel and council chief executive Dawn Baxendale will again hear community pleas to clear the air.

Southern Demolition and Salvage will work 12-hour days, six days a week, to remove 26,000 cubic metres of material from the fire-damaged filters from 6 June.

The council has warned the smell could worsen as material deep inside is exposed to the elements and starts rotting, leaving Ally Enright contemplating a winter indoors.

"If it gets worse I'm probably not going to want to go outside at all," she said.