Authorities are asking pregnant and breastfeeding women to move temporarily outside of an area where a fire has been burning near Hamilton.
The Waikato Regional Council said a precautionary health notice had been issued to residents within three kilometres of Puke Coal's landfill in Pukemiro.
A fire has been burning at the site since August.
A preliminary health assessment was done last week and indicates there is potential for increased levels of dioxins in the atmosphere, which can pose health risks.
Testing will be done when specialist equipment arrives from overseas.
Waikato District Council chief executive Gavin Ion said the welfare response team advised some members of the Pukemiro and Glen Afton communities to find other accommodation.
"This is a precautionary approach because we promised the community we would do everything we could," he said.
The advice focused on women who are pregnant and those who are breastfeeding.
Only a small number of people were likely to be affected by the health notice, the council said.