Lead battery recycler Exide says it is confident a fire at its Lower Hutt plant has not exposed the public to lead emissions.
The company says early indications suggest the weekend fire broke out from an electrical source near the plant's roof.
Spokesperson Mark Unsworth says 90% of the smoke stayed inside the Petone building because of an extraction system designed to retain emissions.
Mr Unsworth says Exide will release the results of monitoring for lead emissions when they come through.
Greater Wellington Regional Council says it has prosecuted the company twice in the past four years for breaching its allowable lead emissions level.