The cause of the blaze in central Auckland remains unclear, but Fletcher Building has confirmed blowtorches were being used on the roof on Tuesday, the day the fire broke out about 1.15pm.
Unite senior organiser Joe Carolan claims three workers passed out today and others had complained of a burning feeling in their throats after returning to work yesterday.
"It wasn't the fire that was the hazard, it's the stuff that we're breathing in. And we were breathing it in for far too long."
The strike was also about giving workers a weekend, something Unite had previously campaigned on, Carolan said.
SkyCity responded to say emergency officials had confirmed yesterday that the fire was under control and it was safe for business to resume.
"Air quality has been rigorously monitored over the past three days, consistently meeting all regulatory standards, at no stage showing any level of threat."
Streets still closed
Fire and Emergency say they want to reduce the disruption to CBD traffic, but say they will be moving a large crane into Nelson St tomorrow.
Fire crews tackling the blaze are still in "active firefighting mode" and are being confronted with pockets of flames today.
Fire and Emergency incident controller Dave Woon said today's work also included an "overhaul" phase as firefighters pull off iron and roofing and sealing materials from the roof.
While firefighters hope to reduce their "footprint" around the scene a large crane will be set up in Nelson St tomorrow.
Woon told reporters that fire crews had done an "outstanding job".
"We still have active fire fighting going on. There are still fires in pockets," he said.
Mike Shaw, who is leading the recovery team said: "This is new to us from an urban perspective, this is the first time we've put a recovery team together.
"We're working with all the local stakeholders and business to make sure that everything gets back to normal."
Shaw said it is was hard to say how long the surrounding CBD roads would remain closed.
"It may take a couple of days, or up to a week."
Shaw said they were in communication with Worksafe, Civil Defence and Fire and Emergency.
Six days to pump flooded basement
Safeswim programme manager Nick Vigar said it would take up to six days to pump water out from the flooded basement carpark.
Water was originally pumped into the stormwater network for 20 hours, but was switched to the wastewater network from 6.30pm yesterday when their testing confirmed that run-off contamination levels were "sufficiently low".
"Our main concern was that emergency services needed to pump water from an immediately dangerous situation."
Vigar said the water in the basement had some hydro-carbon contamination and could be sufficiently treated at a wastewater treatment plant.
They are still waiting for eco-toxicology results which are expected to come in after the weekend.
Vigar advises the public to treat water as potentially hazardous, and there were some reports the water was 'not particularly discoloured'.
He said he doesn't expect contamination levels to increase while cars are in the flooded basement.
Still a lot of work to be done: Goff
Meanwhile Auckland mayor Phil Goff is feeling positive after a hectic week of 4.30am starts since one of Auckland's biggest fires in recent years broke downtown on Tuesday.
"I'm breathing in fresh air and I won't need to get my suit dry-cleaned at the end of today - which is good, because I was running out of suits,'' he laughed.
The mayor said he had been briefed at 5am and then constantly throughout this morning by authorities about the situation.
All indications is that the fire at SkyCity's new convention centre is definitely out - save for a few hot spots needing to be put out every so often.
"We're really on top of that now. We've still got a whole lot of work to be done, but it's getting back to business as usual in the city centre''.
