TORONTO - Carbon monoxide is often referred to as the silent killer because it's odourless and colourless, and its victims can succumb without realizing what's happening.
And in winter, when there might be more power failures, problems with chimneys or a tendency to want to warm up the car in the garage, people need to be especially aware of how to prevent carbon monoxide poisoning and what to do if they come across such a situation.
Tragically, a family of four in Woodstock, Ont., died late last year after carbon monoxide from a blocked vent pipe in a natural gas fireplace seeped into their home.
And on New Year's Day, the Roman Catholic archbishop of St. John's, N.L., was rushed to hospital after he was found semi-conscious in bed after failing to show up to conduct mass at the basilica.
Archbishop Martin Currie, 65, was still in hospital Monday recovering. A church official said he was "doing quite well" and expected to be released this week.
"It seems what happened was that part of the liner in the chimney broke off and fell down into the chimney, partially blocking the chimney itself," said Rev. Frank Puddister.
"So the furnace actually backfired sometime during the night, and then some smoke and soot and gases escaped into the house. ... Apparently he'd been asleep, so he ingested the carbon monoxide."
Cases like these are why emergency officials can't stress enough the importance of a functioning carbon monoxide detector in the home.
"Our best defence with carbon monoxide poisoning is to prevent it," William Chute of the Paramedic Association of Canada said from Vancouver.
Statistics are hard to come by, but the B.C. Poison Control Centre reported that in 2004, 121 people had carbon monoxide - or CO - poisoning in that province. And in 2002, more than 12,000 calls related to carbon monoxide were received in Ontario, according to data compiled by the Canada Safety Council.
"What carbon monoxide does is it interferes with the body's ability to use oxygen, and to deliver oxygen," explained Dr. Wes Palatnick, a consultant toxicologist for the Manitoba Poison Control Centre.
"So they tend to get symptoms related to oxygen deficiency, so they may be very mild symptoms, such as a headache, nausea, malaise - it may in fact look like a flu."
On the other hand, he said, very severe toxicity can affect the central nervous system and cause seizures or a coma, and the patient could sustain heart injuries as well.
Health Canada says that at high levels - or even low levels over a long period of time - people can experience dizziness, chest pain, tiredness, poor vision and difficulty thinking.
"People can die," said Palatnick. "It's one of the major causes of poisoning deaths in North America."
Chute said that a civilian who comes across what could be the scene of a carbon monoxide poisoning should remain cautious.
"The best thing to do is to try and ventilate the area with fresh air from the outside as quickly as possible, but to also do so in such a way that it doesn't put your own health and safety at risk," he said.
"I would have a hard time, for example, advocating that somebody go into a garage where there's suspected carbon monoxide poisoning because we don't want to have another patient to succumb to the fumes."
Rather, open a garage door or windows from the outside and call 911.
Would-be rescuers might be tempted to think they can hold their breath for the short period of time it would take to run inside and pull someone out. But they should avoid the temptation, Chute said.
"That's actually the number 1 reason why we have two and three people that go down in these sorts of situations."
"What people don't realize is that when they're breathing in that carbon monoxide, they're displacing the oxygen that's in their system already," he added.
First responders - often firefighters - normally have self-contained breathing apparatus so they can safely enter the area. When paramedics arrive, they assess the situation.
"If a person was still conscious and able to follow our commands we would have them come outside into the fresh air and treat them with oxygen therapy," Chute said.
"If somebody was unconscious and stopped breathing, then obviously we have the equipment to help people breathe and if needed, perform CPR and have our defibrillators ready as well."
At the hospital, physicians take over.
"If the patient is critically ill we look at certain things such as their airway blood pressure, vital signs, etc.," said Palatnick, who works in Winnipeg and is a board member of the Canadian Association of Emergency Physicians.
"And if they're stable, the first key is to do a carbon monoxide level. While we're waiting for that to come back, the patient should be put on 100 per cent oxygen."
Oxygen will decrease the time that the person has the carbon monoxide in their body, he said.
The higher the level of carbon monoxide, the worse the prognosis.
"(At) levels greater than 40 or 50 per cent, people have a high incidence of having very bad outcomes, whether it's death or sort of chronic effects," Palatnick said.
The use of hyperbaric oxygen is somewhat controversial, he said, and there's "really there's been no definitive proof that it's effective."
He does use it for the occasional patient, though.
"Examples include pregnant women with a level greater than 20 per cent, and the reason being there's a higher incidence of fetal loss and stillbirth. If someone's got a very high level of over 40 per cent, with decreased levels of consciousness, I probably will send them."
In terms of prevention, Chute said people need to use common sense.
"We don't want to see people running their vehicles inside, we don't want to see people using their barbecues inside or gas powered stoves inside," he said.
If the power goes out and it's cold, don't bring a propane heater or barbecue inside.
"Obviously that's just a recipe for disaster. You need to have those types of appliances in the outdoors in a well-ventilated area."
