SASKATOON -- The plumbers who repaired the carbon monoxide leak at a Saskatoon apartment building say the issue originated from the chimney.

Dangerously high carbon monoxide (CO) levels were detected inside 12 Bateman Crescent on Thursday evening. 

All residents were evacuated from their units. Nearly 50 people, including several children, were received medical attention for high CO exposure. 

Brad Williamson and Craig Poggemiller, co-owners of Proactive Plumbing, were called to the apartment — along with firefighters and crews from SaskPower.

Williamson said the leak was caused by a deteriorating chimney. 

“There was wear and tear. The stainless steel just wore out and started leaking. And then with the wind, coming back in with the intakes of the boiler, it was mixing improperly and had to be re-done,” Williamson told CTV News. 

“It can be really scary because it’s carbon monoxide and it can be really harmful for anyone. The levels were really high, so we had to fix up what was leaking and replace everything with new [parts].”

Williamson said a similar issue was detected in a neighbouring apartment at 20 Basement Crescent. 

“We ended up going to the rest of the buildings and noticed one other building was doing the same thing,” he said. 

Residents allowed back inside

Following the repairs, residents are now allowed back inside their suites, according to the company that owns the building. 

“Both the Saskatoon Fire Department and SaskEnergy have approved the building for occupancy,” Mainstreet Equity Corporation told CTV News in an emailed statement. 

Resident Gloria Sognoso spent the past four days at her son’s home as a result of the evacuation. 

“I’m back now because the manager called me an hour ago and said, ‘You can go back in,’” Sognoso told CTV News.

“Fingers crossed.”

Building was up to code

Fire crews found the highest levels of carbon monoxide in the building's boiler room, at 400 parts per million. The fire department said at those levels people can die within about two hours. 

While the apartment didn’t have a CO sensor, the building was still up to code.

Because of the age of the building, CO sensors are not required under its relevant building code. 

“The building code is not retroactive,” Assistant Fire Chief Wayne Rodger said.

“Every [building code] revision is not intended for every existing building to come up to those new standards.”

Rodger recommends people living in shared spaces, such as apartment or condo buildings, install personal carbon monoxide detectors in their suites. 

Dr. Mark Wahba, the emergency room physician who first advised of the potential carbon monoxide issue after seeing symptoms in a patient, was presented the fire department's Award of Merit on Monday.

During the ceremony, which was held virtually due to COVID-19, Wahba said he hoped the incident would lead to change.

"I hope moving forward that we can get carbon monoxide detectors in all homes and buildings in the province. I don't know why it's only buildings after 2009. I can't understand that," Wahba said.

Williamson said new CO sensors have been installed in the buildings as a result of the incident. 

Carbon monoxide has no smell, taste or colour. It’s produced whenever fuel, such as natural gas, is burned.