The thick blackfumes covered the sky over eastern and southern parts of the city, prompting a series of warnings to be sent out by Fire and Emergency New Zealand.
People living in the area surrounding the fire were told to shut all doors and windows and told to not go outside unless necessary.
Residents as far as 19km away in Maraetai reported smelling smoke, described as like burning plastic.
Train services were halted for a period of time, and neighbouring businesses were forced to stop trade for most of the day.
Firefighters battled a blaze in a pile of scrap metal at a yard in South Auckland's Favona. Photo / Hayden Woodward
Now, fire investigators have revealed what started the inferno - “lithium batteries”.
Fire and Emergency New Zealand district manager Brad Mosby confirmed the cause today, saying lithium batteries were found in items such as vapes, cellphones, tablets and electric bikes, among others.
“FENZ noted unless properly disposed of, lithium batteries can end up in landfills or scrapyards where they can cause fires, which was the case with Sims Metals.”
Mosby said anyone who needed to dispose of a lithium battery should separate it from their general rubbish and look for a hazardous waste or recycling centre near them.
“FENZ has been working closely with the Auckland City Council and Sims Metals management regarding the safe disposal of lithium batteries.”
Fire and Emergency crews work to put out the blaze at Sims Metal on James Fletcher Drive in Favona, South Auckland on May 31. Photo / Alex Burton
More than a dozen fire crews were working to get the fire under control on James Fletcher Drive in Favona which was reported to emergency services at just after midnight on May 31.
When the blaze broke out Fire and Emergency Waitemata assistant area commander Garry Lane said firefighters responded to the third alarm fire where there were a number of cars used as scrap ready to be recycled within a large pile on fire.
“We have 14 fire trucks and approximately 40 firefighters at the scene,” Lane said.
“So our plan is in liaison with our management we are separating the piles out to make them smaller to be able to extinguish them quickly.
“It is a really big pile, 10m high.”
Lane said crews were working from aerial appliances and ladder trucks.
One local business owner called the recurring fires “inexcusable”. He told the Herald Sims Metals ought to be investigated for any issues. Auckland Council said it would review any issues which may have caused the fire.
Fire and Emergency NZ’s Mosby said they had responded to nine fires at Sims Metals since November 2017.
“Four of these required firefighting activities, two of which were scrap metal pile fires in 2018 and 2021,” Mosby said.
