Test results from the Southern District Health Board's mobile oral health clinics have shown they meet workplace and environmental standards.
The board temporarily removed seven mobile oral health units from service as a precaution, following concern about the levels of formaldehyde detected in a Canterbury DHB mobile oral health unit of the same design.
Southern DHB Medical Officer of Health Marion Poore said the results clearly show levels of formaldehyde are well below workplace exposure standards and the air quality guidelines.
The units will be back in service next week.
