'It's eye-opening and frightening.' The stark reality of being a triple-0 call operator. 

Harrison Searle is one of the voices at the other end of the line when you call ‘000’.

The 21-year-old has been an emergency medical dispatcher (EMD) for 12 months now, and absolutely loves his job.

He’s the one who actually sends the paramedics’ lights and sirens to car crashes, cliff falls, stabbings and suicides after taking the initial call.

WATCH: Ambulance Australia kicks off for another season on Thursday. Post continues after video.

Despite all of his training (it took eight weeks of intensive training and then a month as a student EMD to become qualified) there’s one thing that really took the Brisbane local by surprise.

“Growing up it was almost like I was wrapped in bubble wrap. I never knew just how common mental health and suicide are in the world until I started working for Ambulance Australia,” he told Mamamia.

Harrison, I think, is like a lot of us. We know it’s bad out there, but can we comprehend just how bad?

On an average Friday or Saturday night shift, Harrison says he can end up taking “call after call” related to mental health.

“It was eye-opening, and it was frightening,” he explained, while reliving his first few weeks on the job.

"I certainly got to an age where I knew mental health was a thing. But I certainly didn't realise how serious it was. For me, it didn't affect me, my family or my friends so I was really, really confronted when I started working and realised its true presence."

In 2018-19, 4.3 million people received mental health-related prescriptions in Australia, according to the Australian Institute for Health and Welfare.

The AIHW research suggests 2-3 per cent of Australians are living with a severe mental disorder, 4-6 per cent have a moderate disorder and 9-12 per cent have a mild disorder.

It's hard just reading numbers, to put that into perspective.

But if Harrison and his paramedic and police colleagues' experiences are anything to go by, it can take up the majority of their 12-hour shift, particularly on weekends.

"A couple of nights ago I had someone call who was having an anxiety attack. He didn't want an ambulance, and I just sat with him for 15 minutes talking. We together just devised a coping strategy for him in that situation," Harrison told Mamamia.

This is where it gets tricky.

On any given night EMDs are juggling a whole range of emergencies - and often don't have time to sit on the phone for hours with a patient. It becomes a careful balance of helping where they can, while making sure they've got their ears across what else is needed of them.

"It's a great job. It's thrilling and exciting. No two jobs are the same... when you press the button and you answer the call, you don't know what you're going to get," reflects Harrison.

They've also got a mental health clinician on staff most of the day, who they can hand a patient over to if they need to. That's only a fairly recent initiative they've introduced.

Harrison is talking to people often on the worst day of their life. Sometimes, it can be their last minutes on this earth.

That can take a toll.

"It would be amiss of me to say calls don't affect us. They do. We are human," Harrison told Mamamia. 

Research from the Australian Institute for Disaster Resilience found rates of PTSD were 8 per cent amongst ambulance employees compared to 9 per cent amongst firefighters and 11 per cent in the police force. In comparison, the prevalence of PTSD has been estimated at 4 per cent in adults in Australia.

Paramedics’ mental health can be affected by the very nature of the job: shift work, fatigue and having to make critical decisions under time pressures.

Not only has 21-year-old Harrison had to quickly learn the hard way about the extent of mental health issues in the wider community, but he's also had to come to terms with the fragility of his own.

"I think you become more aware of your own feelings and how things affect you and things like that," he said. "Before the job I wasn't thinking about that at all."

Ambulance Australia returns Thursday, February 6 on Channel Ten. It airs 7.30pm every Thursday.