The inquest into 2016's deadly thunderstorm asthma event has recommended callers to triple-0 be given an estimated time of arrival for ambulances.
Ten people died after a cool change blew through Melbourne on November 21, 2016, sparking asthma-like symptoms in thousands across the city.
An hour after the storm hit the city, authorities had received an unprecedented surge of calls for ambulance assistance.
A coronial inquest into the wave of deaths found some callers were told an ambulance was on its way when none had yet been dispatched.
This was due to operators — who were unprepared for such an event — following standard scripting.
While the Emergency Services Telecommunications Authority (ESTA) had rostered on extra staff to deal with the fallout of the forecast thunderstorm, it "did not expect an increase in the number of calls requesting Ambulance Victoria attendance", coroner Paresa Spanos found.
This was because "the likelihood of a TA [thunderstorm asthma] event was not appreciated at the time".
"Therefore," the coroner found, ETSA "did not revise the staffing roster for call-takers trained and dedicated to taking calls for ambulance assistance".
While the 12 hours following the arrival of the storm saw ETSA inundated with the "single greatest volume of calls for ambulance assistance" in its history, the coroner noted it was "important to appreciate that the cause of the surge of calls was unknown at the time".
A number of strategies were used to deal with this unprecedent demand for ambulance assistance, however, operators had "no discretion to deviate from the mandated exit script", which been developed over many years and was "thought to allay callers' concerns".
Therefore, operators were "not permitted to provide callers with an estimated time of an ambulance's arrival".
Many who spoke at the inquest complained that they would have made their own arrangements to get to hospital had they been advised of the lengthy delays.
The coroner found that providing estimated times of arrival would allow callers to consider their best transportation options in an emergency.
Fifteen minutes to cardiac arrest
Because of grass grown in the northern parts of Victoria, Melbourne is a hotspot for thunderstorm asthma, and conditions were right for a perfect storm the day of the event.
Rye grass pollen swept in from the countryside north-west of the city and burst into very fine particles, causing illness across Melbourne.
By 6:00pm, authorities were flooded with calls for help.
The victims were mostly men, with an average age of 36, and were predominantly from Asian backgrounds who had recently immigrated to Australia, this year's inquest heard.
The youngest victim was 18-year-old Greenvale student Omar-Jamil Moujalled, who reported severe symptoms an hour after the cool change came through, and died around an hour later.
The inquest also heard eight of the victims were from Melbourne's north-west, where the storm might have hit hardest and where socio-economic conditions and access to treatment might have been a factor.
University of Melbourne allergy specialist Professor Jo Douglass told the inquest that there was, on average, 15 minutes between victims experiencing severe symptoms and then entering cardiac arrest.
While most victims died within a week of the storm hitting Melbourne, two — Min Gui, 29, and Le Hue Huynh, 46 — died in the following months.ABC