Dan Moir was one of several parents watching their children play in a weekend-long hockey tournament in December 2024, when his son came off the ice not feeling well.
Moir, an off-duty firefighter from Calgary, says it wasn’t like his son to experience a headache and nausea but he did what he could to take care of him.
But it was only 10 to 15 minutes later that a second player came off the ice with similar symptoms. Then, a third.
At first he thought maybe it was a flu, but he noticed the boys started feeling a bit better once they left the rink and got some fresh air. Moir continued to ponder the cause as they made their way home to Calgary.
“I started going through the Rolodex of symptoms in my head of what that could be, as a firefighter,” he told CBC News. Those symptoms, he says, checked a lot of boxes for carbon monoxide (CO) poisoning.
Moir later found out his suspicions were correct and that his son — along with 22 other children, around the ages of 10 and 11, and two adults — would need to be treated at Calgary’s Alberta Children’s Hospital.
Moir is one of three parents who shared their stories and concerns in the Canadian Medical Association Journal (CMAJ) highlighting the risk of exposure to CO and nitrogen dioxide (NO2) emitted by fuel-powered equipment used in ice arenas.
Despite there being federal recommendations — but no firm rules —about air quality in ice arenas, their research found best practices aren’t universally adhered to, including having CO monitors installed, and that CO exposures at hockey and skating rinks are more common than many people might think.
Local jurisdictions may also have their own standards and measures in place to manage air quality.
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The CMAJ article did not mention the name or location of the arena. But the Village of Rockyford, about 90 kilometres northeast of Edmonton, confirmed the incident on its Facebook page at the time.
No village or arena officials were available for interviews for this story.
Moir and the other co-authors hope that more awareness might help reduce the chance that other families will have to deal with what they went through.
“We’re a country that loves ice sports,” said co-author Laurie Lee, a pediatric nurse practitioner and epidemiologist. “My kids spent a lot of time in an arena and they should be safe.”
After he and his son drove away from the rink, Moir called a local fire department and suggested they test the facility.
Fire officials detected elevated levels between 90 to 150 parts per million, Moir said, with the highest levels in the dressing room his son and his team had been using.
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Health Canada recommends immediately stopping all public activity on the ice when CO levels are greater than 25 parts per million and that public health officials should be notified to investigate.
“My understanding was the heat exhaust was blocked by a bird’s nest and that exhaust was dumping back into a dressing room where our boys were,” Moir said.
He and other parents were dismayed to learn that there was no CO monitor on site and that they are not officially required.
“To learn that these arenas do not have rules … is mind blowing,” said Jessica Marshall, whose son had one of the higher CO levels among the young players when medical workers tested him at the emergency department.
“It’s such a simple thing that can be fixed just like a smoke detector,” she said, adding that her son now carries his own handheld monitor with him to rinks because he’s afraid of having to go through the ordeal again.
But what happened at that tournament, which involved four teams of young players, wasn’t an isolated incident.
The CMAJ article cited 11 CO poisoning incidents and one NO2 poisoning at indoor ice rinks across Canada between 2016 and 2026.
After one in 2019, nearly 80 people sought treatment at hospital after being exposed to carbon monoxide at a St. John’s arena.
More recently, a carbon monoxide leak sickened a number of people at a facility on the Piikani Nation, in southern Alberta, in August 2025.
Vittoria Vecchiarelli, with the Canadian Institute of Public Health Inspectors, says combustion-engine equipment — such as ice resurfacers and edgers, heaters and boilers — are common sources of carbon monoxide and nitrogen dioxide.
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“If that equipment is not maintained or well tuned on a regular basis, they can emit higher levels of those pollutants,” said Vecchiarelli, who is involved in the inspection of ice rinks and contributed to the peer-reviewed CMAJ article.
“With insufficient ventilation, they can be allowed to accumulate to more dangerous levels.”
Carbon monoxide is odourless, tasteless and colourless — unlike nitrogen dioxide which has a harsh smell and reddish-brown hue — so people may not know that they’ve been exposed until they exhibit symptoms and have been tested.
Vecchiarelli says symptoms can include dizziness, headaches and nausea but CO also interferes with the blood’s ability to carry oxygen.
And that’s certainly the case for athletes on the ice, exerting energy and breathing more heavily, she says.
The symptoms can be alleviated with oxygen, either from fresh air or administered by health-care workers. More extreme cases may require oxygen therapy using a hyperbaric chamber.
But Dr. Bruce Campana, an emergency physician at Vancouver General Hospital and clinical assistant professor at the University of British Columbia, says there are other serious conditions that can emerge weeks or even months after a CO exposure that has gone untreated.
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Those can include personality, emotional and cognitive changes that can affect a person’s daily life, he says.
“It’s insidious,” he said.
Campana, who was not involved in the CMAJ article, says he believes many “reasonably up-to-date arenas” will likely have taken steps to prevent carbon monoxide poisoning.
“Because if something happens, he says, “the risk is high to multiple people and obviously the liability is high.”
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