Amberley tyre fire: Air quality monitors installed as the fire reaches its fifth day

Residents near a large tyre fire in North Canterbury are being urged to keep their windows and doors closed as the fire continues to burn out.

Forty-five firefighters were called to the burning of 160,000 discarded tyres in Amberley at about 3:10pm on Friday afternoon.

But because of the potential for contamination of groundwater, not a drop of water has been put on this fire. 

Authorities instead have had to stand back and let it burn.

"The bulk of it now is ash and steel... obviously still some fuel there" Environment Canterbury region manager Andrew Arps said.

That fuel - 160,000 discarded tyres that have been burning for five days now.

"A number of the fire crews said this was a bit weird to have to stand back, they made the site as safe as they could so that's what they focussed on not putting any water, not putting any foam on... It was a bit strange for them."

As smoke continues to billow across the area, air quality monitors have been installed at nearby Broomfield school.

Authorities are hoping the fire will burn out in the next couple of days.

"When it's safe enough, we'll move into the plan of smothering the fire then capping it with clay so it's got an impermeable cap stabilising the site," Arps said. 

"So if there's a rain event we don't get anything through to the water table."

Arps says eventually it will all be moved off-site and discarded safely.

A 63-year-old man has been charged with arson over the fire.

He received a registrar's remand at a scheduled appearance in the Christchurch District Court on Tuesday afternoon, and is summoned to appear later this month.