The Environment Protection Authority has confirmed that testing of the Port Kembla Copper stack revealed no signs of asbestos.
There has been concern from the public that the brickwork in the stack contains asbestos and its planned demolition on February 20 would release it into the air.
But EPA Illawarra manager Peter Bloem said both the EPA and WorkCover had undertaken independent tests of the stack in September last year for asbestos.
"Samples were collected from a number of different locations within the stack of the concrete, brick and mortar used to construct the stack," Mr Bloem said.
"All samples were analysed by NATA [National Association of Testing Authorities] accredited NSW government and independent laboratories.
"No asbestos was detected in any samples."
The EPA also conducted testing for "a wide range of metals" at the same time, he said.
"Some metal residues were detected in the lining. However, they are strongly adhered to the brickwork and the quantity of material is very small compared to the total mass of the stack."
In December last year, the EPA also tested bricks for technically enhanced naturally occurring radioactive materials (TENORMS). The testing was done to see if "elevated levels of TENORMS were present in the inner wall of the inner stack that was exposed to previous smelting emissions".
The results were compared with those taken from normal bricks and concrete unrelated to the Port Kembla Copper (PKC) site.
"No elevated levels of radioactivity were detected in the testing," Mr Bloem said.
The testing was in response to "community concerns".
He said these results were used to ensure Port Kembla Copper had sufficient dust and metals management measures in place.
These included "dust-suppression devices", including specialised water sprays and cannons, and air-quality monitoring and reporting programs.
"The demolition of the PKC stack is a unique and highly specialised activity and the location of the stack very close to residential areas demands a high level of protection be achieved," Mr Bloem said.
"The company has made a number of commitments to the community and the EPA in terms of protecting the environment and property and the EPA expects the company to honour these commitments."