VANCOUVER - Eighteen years as a firefighter had exposed Greg Gauthier to endless trauma but a call involving a tour bus hitting a family triggered his descent into mental illness as intrusive thoughts and sleepless nights became his daily existence.

Gauthier, 48, could no longer function at work but the stigma of asking for help in a job where chaos is the norm initially prevented him from reaching out.

"I knew something was wrong right after that call," he said of the August 2017 incident when an American man died and three others were injured as a bus rolled into a crowd of tourists, pinning at least two people beneath the vehicle.

Gauthier said it wasn't the most horrific situation he'd encountered, but it was the one that broke him emotionally.

Over and over again, he would relive the scene of people taking cellphone video of the crash scene as police dealt with a hoard of visitors near a busy cruise-ship terminal and convention centre. Gauthier's family life began to unravel and he felt helpless.

"When you don't have control of your mind and when you can't block those thoughts then you feel like you're losing control and it's an incredibly distressing feeling," he said. "I'm still dealing with it a year and a half later but I'm certainly managing it."

Gauthier finally realized that as a supervisor he had to set an example for the rest of his crew at a Vancouver fire hall so colleagues who had also been at the scene and others like it could feel free to talk about their struggles in a job that required them to soldier on day after day.

"There's a stigma and we're trying to break that down," he said as he prepared to share his experience and gradual return to work at a conference of first responders meeting in Richmond, B.C., on Thursday and Friday.

About 350 people including firefighters, police officers, paramedics, dispatchers as well as their unions and associations are taking part in the event that will feature Gauthier and others in jobs where trauma is part of the job but talking about its impact is not.

Gauthier said he wondered if he'd have to prove himself all over again if he took time off, if he'd put the "brotherhood and sisterhood" of his job at risk.

"Part of my healing, part of my therapy, is talking about it," he said, adding he got counselling. When he returned to work after five months he didn't initially go out on calls, worked shorter days and slowly exposed himself to the rigours of the job, including driving past the accident scene that led to his breakdown.

WorkSafeBC, the provincial workers' health and safety agency, brought together a committee of 14 first responder agencies that organized the conference.

Trudi Rondou, senior manager of industry and labour services for WorksafeBC, said the goal is to work toward dismantling the stigma of mental illness suffered by those who focus on protecting public safety but often need help themselves to cope with extraordinary stress.

The key to getting that help is a commitment from employers to put prevention, peer-support and return-to-work programs in place, she said.

"We did some research among first responders and that was one thing we clearly heard, that this has to be a culture change and we need to make sure our leaders are invested in this, not only with their words but with the budget and action behind it."

Otherwise, the costs range from low productivity, a high number of sick days and the potential for long-term disability from post-traumatic stress disorder, Rondou said.

Last year, the British Columbia government amended legislation allowing first responders including emergency medical assistants, firefighters, police officers, sheriffs and correctional officers to make WorkSafeBC claims for compensation and health-care support if they'd been diagnosed with a mental health disorder, without having to prove it was related to their work.

Greg Anderson, dean of applied research at the Justice Institute of B.C., said most provinces have similar legislation, but coverage for first-responder jobs varies.

In Nova Scotia, for example, emergency-room nurses are included in so-called presumptive legislation while some provinces have coverage for post-traumatic stress injury and others only accept claims for post-traumatic stress disorder, Anderson said.

Last June, the federal government adopted presumptive legislation to combat post-traumatic stress disorder experienced by federal first responders, including employees of the RCMP, the Correctional Service of Canada and those in enforcement roles for Fisheries and Oceans Canada.

On Wednesday, Conservative MP Todd Doherty, who had introduced the bill, asked Prime Minister Justin Trudeau during question period why the government had not yet acted on the legislation to develop a national action strategy.

"This spring we will be moving forward with the plan to fight PTSD that the minister of Public Safety and Security will put forward," Trudeau said.