A second attempt to measure lead in air levels near a battery recycling plant north of Wellington is under way.
Lower Hutt company Exide Technologies was fined $30,000 last year for releasing too much lead into the air in breach of the Resource Management Act.
It was the second offence by the company in nine months.
Wellington Regional Council recommenced monitoring the plant and says the tests will run until the end of June.
It says its tests will measure human exposure to lead, while Exide's tests will focus on compliance with the Resource Management Act.
The council will collect dust particles every second day at nearby sites.