Health and safety representative Chit Chit Than, who has worked as a mental healthcare nurse for 16 years, lodged a statutory safety notice against Hunter New England Local Health District in June 2022 in response to claims co-workers were being forced to work alone in the unit's observation area.

The NSW Industrial Relations Commission heard last year that there were "high rates of physical and verbal abuse from patients" in the observation area.

"Staff in this area are working with patients that are very acutely unwell, and who pose significant violence and aggression risk, with those risk levels changing regularly and without warning," Ms Than wrote in the safety notice.

"There have been previous incidents of extreme patient violence and aggression towards staff in Maitland mental health which demonstrates the level of risk."

Ms Than gave evidence at a hearing last year, where she challenged SafeWork NSW's decision to cancel the safety notice, about the risks faced by staff.

She detailed how a colleague was assaulted by a patient in 2020 and lost nine teeth, suffered a fractured ankle and had several fingers severed.

In June 2022, Ms Than issued the health district with the provisional improvement notice (PIN) claiming staff were being forced to work alone in the volatile observation area.

In the notice, Ms Than said the risk of harm was increased because the duress alarm system did not work in certain areas of the unit, meaning staff working alone could not call for help.

She said there was "minimal line of sight" to the observation area from the nurses' station and there was no staff to monitor CCTV footage designed to mitigate risks.

According to Ms Than, sound proofing installed in the observation area meant that if staff called for help, they would not be heard.

She said a sound system designed to transmit audio from the observation area to the nurses' station switched itself off after a few minutes and staff struggled to remember to continually switch it back on.

"Compounding all of the above, there is currently no admission or exclusion criteria for the unit, resulting in a level of patient acuity that cannot be safely managed," Ms Than wrote.

"A model of care setting out clear admission and exclusion criteria would ensure that the ward is staffed appropriately for the acuity of patients admitted."

Hunter New England Health requested SafeWork NSW appoint an inspector in July 2022 to review the situation.

The provisional safety notice was cancelled two months later, following a SafeWork NSW report which found there was "insufficient evidence available" that management had directed staff to work alone.

The inspector also found there was not enough consultation with the health district to remedy the issues before the safety notice was issued, considering the mental health unit had only been open for six months.

In September 2022, the health district was issued with an improvement notice by SafeWork NSW after it was found the "Code Black system" in the mental health unit was not working properly.

"Specifically, the duress alarm/zebra phone system has on numerous occasions failed to initiate a Code Black Response due to technical grounds (remote signal/blackspot, handset failure) and the response time of Code Black Response team including security staff for staff in the observation unit has been excessively long and as such has placed workers and others at increased risk of injury," the inspector said.

The report found that at times it took 15 minutes for staff to be notified the alarm had been activated.

The commission heard this was due to a software issue, which was later addressed, and the frequency of delays was reduced, but the problem was not entirely resolved.

Ms Than then requested an internal review of the cancellation of the safety notice.

The internal review upheld the decision to cancel the safety notice, and Ms Than challenged the decision in the Industrial Relations Commission, with hearings held in May and August last year.

Last month, while acknowledging that Ms Than was "genuinely concerned about the health and safety of nurses working in the unit", Commissioner Janine Webster upheld the decision to cancel the safety notice.

The commission heard that Hunter New England Health had completed upgrades to the unit to improve staff safety.

These included installing mirrors to fix the line of sight issue, repairing the intercom switch, employing more security staff to respond to calls for help and improving the duress alarm system.

Commissioner Webster said it was clear there were times when it was not safe for a nurse to work alone in the observation area.

"However, I am not persuaded that it is never safe for a nurse to do so," she said.

"The risk of a patient being aggressive or violent is dependent on many factors."

Commissioner Webster described the observation area as "dynamic, changing with the patients and their circumstances".

"Given the small size of the observation area and the evidence that not all patients are predisposed to aggression and violence by reason of their illness or otherwise, I accept that there are times where the presence of two nurses in the observation area is unnecessary, for safety reasons," she said.

She confirmed the outcome of the internal review undertaken by SafeWork NSW to cancel the provisional improvement notice.