Mobile oral health units in Southland and Canterbury have been taken out of service due to a chemical scare.
The Southern District Health Board said it has temporarily removed seven units as a precaution after high levels of formaldehyde were found in a Canterbury unit of the same design.
It said an eighth unit remains in service as it is has a different design.
Southern Medical Officer of Health, Dr Marion Poore said the formaldehyde fumes in the Canterbury unit may have come from tiles used in the suspended ceiling.
She said that at the kind of concentrations found, the risk to anybody who was in the unit for a short appointment would be negligible.
The effect on staff or patients may have been itchy eyes, a headache or a sore throat in acute cases. The symptoms would have quickly diminished once they left the environment
In some cases pre-existing conditions such as asthma could worsen.