It was a series of catastrophic errors that caused the death of the Ghanem family's baby boy, John, and serious brain damage to a baby girl at Bankstown-Lidcombe Hospital, found the Chief Health Officer's final report released Saturday.

Their suffering was exacerbated by health minister Jillian Skinner's decision to publicly release the report just 24 hours after their legal counsel had received it, the family's lawyer said.

Two employees have been stood down, a further 14 people have been interviewed and 13 other personnel, including senior manager, have been flagged by investigators tasked with discovering how the newborns were exposed to nitrous oxide instead of oxygen in a resuscitation unit at the hospitals in June and July this year.

The first parlous error set in motion the tragic failures long before the two mothers had even conceived their babies.

In July 2015, a contractor for medical supply company BOC Ltd incorrectly installed the gas pipes in one of the hospital's operating theatres. BOC also failed to properly test and commission the pipes, found the report.

It was all the more tragic considering the hospital decided to install the pipes to protect newborns, after after a gas cylinder ran out of oxygen as staff attempted to resuscitate a baby in January 2014.

"[T]here were failings in the installation of the piping, by BOC," chief health officer Kerry Chant said at a press conference on Saturday.

Existing pipe work supplying nitrous oxide had been mislabelled as oxygen, the report read.

If correct procedures were followed  when the gas was installed in July 2015 the error would have been identified, it concluded.

"That commissioning and testing process was also flawed … so you have the combination of those two errors that led to this fatal incident," Dr Chant said.

South West Sydney Local Health District, which oversees the hospital, and BOC failed to comply with national standards for installing medical gas, the report found.

"Clearly we have failed the families [of the babies]," she said.

The Ghanem family were "deeply distressed" by the report's findings, their lawyer Stephen Mainstone said in a statement on Saturday.

"If proper procedures had been followed regarding the installation and testing of the gases, this tragedy would not have occurred," he said.

The family's pain and suffering had been further exacerbated by the health minister's insistence on providing the interim and final reports to them without giving them sufficient time to properly consider the findings before she released them publicly, Mr Mainstone said.

"The minister has continually stated she is deeply sorry for the pain and suffering caused to the family. The timeliness of the release of these reports has done nothing to relieve that," he said.

Mr Mainstone received the report via email at roughly 11.30am on Friday.

The family had not had the chance to see the report, and would not have time to process its contents before its was released on Saturday, Mr Mainstone said.

Health Minister Jillian Skinner did not front the press conference with Dr Chant. Her office said the Minister has apologised for the pain and suffering caused to the families. She did however briefly appear for TV cameras later in the day.

Opposition leader Luke Foley said it was "utterly outrageous" that Ms Skinner did not "front up" and she should be dumped immediately.

"I find it disgraceful that the government slips out a report through a public servant on a weekend," Mr Foley said.

"Babies have been gassed in a NSW hospital ... It is frankly a disgrace that neither Mike Baird or Jillian Skinner is standing up today," he said.

The Health ministry has taken charge of continuing investigations into to whether further disciplinary action is needed, Dr Chant told the press conference.

Two employees have been stood down over the errors, a senior health bureaucrat and former general manager at the hospital, and a biomedical engineer.

An additional 13 people have been interviewed over the course of the investigation and a range of other people have been flagged for further interviews.

The Health ministry has taken charge of continuing investigations into to whether further disciplinary action is needed, Dr Chant said.

"It is important that we afford those individuals procedural fairness," she said.

"The report also identifies that there is problems with the level of governance in relation to the commissioning of the clinical infrastructure of Bankstown Lidcombe Hospital and that need further investigation," she added.

The report made several recommendations, including a separation between the person who installs the gas and the person who tests the installation.

SWLHD has been put on "performance watch" to ensure recommendations were implemented, she said.

"We are taking step to further strengthen our system to ensure the public has confidence that this will not happen again," Dr Chant said.

In a statement on Saturday, Ms Skinner said: "The public can be assured the health system is safe".

"The Ministry of Health will accept all recommendations raised in the Chief Health Officer's final report to ensure this tragic error can never happen again."