A routine day of mail deliveries turned into a tense situation for a Canada Post employee in Winnipeg this week, when the carrier discovered an unresponsive woman while on his mail route and chose not to offer her CPR.

Corey Gallagher has been delivering mail in Winnipeg for nine years. On Tuesday morning, his daily route took him to a subsidized apartment building, where he discovered a woman lying in the lobby, unconscious.

"I've never come across anything like this. This was kind of a big eye-opener and kind of a big reality check,” Gallagher told CTV Winnipeg.

He says he tried to rouse the woman but she didn't respond. He tried to get help from other people in the building but they walked away. So he called 911.

Gallagher says the paramedic who took the call asked if the woman was breathing and directed him to begin performing CPR while waiting for an ambulance to arrive. Gallagher decided not to.

"I told them I wasn't feeling comfortable, I didn't feel up to it. I think at one point I mentioned there's like white stuff, she's OD’d,” he said.

When he saw the white powder on the woman’s clothing, Gallagher worried it might be fentanyl, he said. He had heard that a dose the size of just a few grains of salt could be lethal and that simply touching the toxic opioid could be deadly.

Gallagher said while the 911 operator repeatedly asked him to start CPR, he refused, not wanting to put himself in danger.

Paramedics arrived on scene within minutes and the woman was transported to hospital. Her condition is not known.

The city says it can't comment on the specifics of the case. A spokesperson says calls like the one Gallagher made are patched through to the Winnipeg Fire Paramedic Service and that callers may be asked to help until first responders arrive on scene.

Brent Fowler, the president and CEO of St. John Ambulance, says fentanyl is posing new challenges for people trained to provide first aid and CPR. He says for bystanders, deciding how much to help is a personal decision.

"The issues at the end of the day are you need to protect yourself and keep yourself safe, first and foremost as the rescuer and then keep your casualty safe,” he said.

“If the scene isn't safe and you can't make it safe, then there's nothing you can really perhaps other than call 911."

The Winnipeg Fire Paramedic Service says it reviewed the call Gallagher made and determined it was handled properly.

Gallagher says he doesn’t fault the 911 operator for trying to convince him to start the CPR.

"I don't blame them because that's their job. That's what they're trying to do. That's why I called them, to try to save a life and hopefully they did that. But I don't feel totally responsible to be doing that,” he said.

Gallagher says it’s unfortunate that while his first instinct was to help, in the end, all he could do was pick up a phone. He knows he did the right thing, but he hopes he never again has to decide between helping and putting his own safety in danger.

With a report from CTV Winnipeg’s Josh Crabb