Historically low air pollution during lock down

NIWA estimates levels were down by three quarters across the country

Road traffic pollution in Auckland, Wellington and Christchurch were between 25 to 35 percent of normal in level 4.

Air quality scientist Dr Ian Longley says we've rarely seen these levels of clean air before.

He says the only other time you see these levels of air quality would be early on the morning of New Year's Day when there's almost no traffic on the road, which only lasts for a couple of hours.