A report has criticised the way the NZ Transport Agency has assessed the potential air quality effects of the proposed Waterview motorway connection in Auckland, saying it could be worse than first thought.
The report was commissioned by the Environmental Protection Authority as part of the consent process for the link.
The authors say they are worried the NZTA has underestimated the volume of traffic which will use the road as well as the emissions calculations.
They say pollution in the Oakley Creek area, which borders the motorway, was also underestimated and will exceed air quality targets.
NZTA says it's confident the research is robust.