The demolition of a Mr Fluffy house last month reportedly created large plumes of asbestos-contaminated dust, exposing a WorkSafe inspector to the deadly fibres.
Residents who lived near the Torrens home were not told of the incident, though WorkSafe ACT and the ACT government were notified.
The government said air-monitoring equipment on the property's perimeter, set up and analysed by a licensed asbestos assessor, found no evidence that the deadly fibres had breached the site's boundaries.
But the head of the federal asbestos agency said air monitoring outdoors was not totally reliable and the neighbours should have been told as a precaution to reassure them they were not at risk.
WorkSafe ACT has since confirmed the private demolition of 9 Darke Street on August 20 created an asbestos-contaminated dust cloud.
At least three workers, including a WorkSafe inspector, were exposed to the fibres as a result. They immediately decontaminated themselves and sealed their clothes in bags.
Tests confirmed the presence of asbestos fibres on the clothes and equipment of the inspector.
In July, the government published the addresses of 1022 Mr Fluffy homes in Canberra. All but a handful of owners are taking part in the buy-back program, selling their properties to the government.
However, one of the eight owners who declined to take part organised a private demolition of the Torrens house.
WorkSafe said safety procedures were adhered to strictly before the demolition: the work plans were scrutinised, all visible asbestos was removed, a glue was used to seal in as much of remaining fibres as possible, and a licensed assessor issued a clearance for the demolition to go ahead.
But it is understood an excavator driver then smashed the building by dropping the machine's bucket through the roof before the WorkSafe inspector had completed further checks, reportedly sending large plumes of dust into the air.
Some of the asbestos-laden dust landed on the inspector.
WorkSafe was notified of the incident but nearby residents were not told of the potential danger.
The response differs markedly from that which followed a suspicious fire that gutted a Mr Fluffy home in Page earlier this month.
In that case, air-monitoring equipment was immediately installed around the house, and government staff door-knocked five neighbours and letter-dropped 43 properties in the area the next day to tell them about the incident.
ACT Worksafe commissioner Mark McCabe said tests indicated that asbestos did not breach the Darke Street property's exclusion zone.
"The licensed asbestos assessor has concluded 'it is safe to say that no elevated airborne fibre exposure occurred at 9 Darke Street'," he said.
"All of the normal controls to ensure that everything that could reasonably be done to ensure asbestos fibres would not be released on to surrounding properties had been put in place."
Mr McCabe said the contractor had told neighbours that the demolition would occur, but did not mention the incident.
He said WorkSafe did not inform the property's owner and "we are unclear what conversations the homeowner may have had with the contractor".
Meanwhile, federal Asbestos Safety and Eradication Agency chief executive Peter Tighe said air-monitoring outdoors could be unreliable.
He said the equipment took samples by sucking air that flowed past it, but dust that escaped upwards into the atmosphere would not have been detected.
He questioned the wisdom of relying on the air-monitoring results.
"The problem is if there is a prevailing breeze taking the dust or fibres away from the monitor, then it's not going to pick up anything," he said.
"You can monitor an area where there's friable asbestos, but if it's upwind of the fibres then it's not going to pick up anything because it's picking up air coming from another area."
Asbestos fibres were very light and could sit in the air for up to three days before settling, he said, adding that neighbours should have been notified.
"People need to be reassured that they weren't at risk and need to have it explained to them as a precautionary approach to protect the public interest."
Mr McCabe said an investigation to determine whether action should be taken against those involved had been launched.
The government would also conduct an independent review after that investigation concluded.