A silent killer trickled into the homes of some New Brunswickers after parts of the province lost power more than a week ago.

Carbon monoxide, or CO, is a gas with no smell, no taste and no colour — an intruder all the more dangerous because it's so difficult to recognize. 

Carbon monoxide poisoning has been blamed for killing two people and putting 42 others in hospital since a severe ice storm blew through New Brunswick last Tuesday and Wednesday.

Most likely, the victims felt safe even as they breathed in the gas, said Robert Duguay, director of communications for New Brunswick's Emergency Measures Organization.

"Without knowing, they can lose consciousness," he said. "They're being poisoned by the carbon monoxide."

What is it?

Fire marshal Douglas Browne on how to detect CO0:20

Carbon monoxide is the product of an incomplete combustion of fossil fuels such as gasoline, oil, coal, wood, propane and natural gas.

When fossil fuels are burned inside a home, the occupants breathe in the toxic air, which saps their blood of its ability to absorb oxygen.

This makes it difficult for body tissues and cells to function properly. 

The gas can also seep into a house from the outdoors, where fuel-burning generators, barbecues, grills and other appliances are used. Vehicle exhaust can also cause carbon monoxide poisoning.

'Without knowing they can lose consciousness.' -Robert Duguay  

"If these are burned or attempted to burn in an environment where there may not be sufficient oxygen, instead of getting more safe carbon dioxide as a combustion product, you get carbon monoxide," said Richard Blais, director of compliance and regulatory review at WorkSafeNB.

In New Brunswick, 10 people died between 2008 and  2012 from accidental carbon monoxide poisoning, according to Statistics Canada. From 2003 to 2007, five people died.

What's being done?

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NB Power crews assess damage after last week's ice storm that left thousands of homes and businesses without electricity. (CBC)

The province has been trying to communicate the risks of carbon monoxide poisoning to residents affected by power outages in areas such as the Acadian Peninsula, where more than 6,000 people were still without power Wednesday.

But since the ice storm, some residents have resorted to generators, space heaters, barbecues and camping equipment as a source of heat inside their homes.

"After several days without power, they're just trying to protect their belongings," Duguay said. 

"People are desperate."

Anyone without power, however, should always use one of the warming centres in the area, he said.

Volunteers, including search and rescue teams, firefighters and members of the Department of Natural Resources, have been going door–to–door in areas without power.

They've been reminding people of the dangers of using heating sources that aren't appropriate for indoors.

Symptoms

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Carbon monoxide poisoning doesn't have many obvious symptoms. Headaches, nausea, dizziness and fatigue can be some of them. (Paul Sakuma/Associated Press)

Nausea, headaches, fatigue and dizziness are among the first signs of carbon monoxide poisoning. With high levels of exposure, a person can fall asleep and never wake up.

Symptoms can arise within minutes to a couple of hours, depending on the amount of CO inside a home.

Earlier this week, Duguay said, a volunteer with EMO found some people at home using a questionable heating source.

They had headaches and were taking medication, without realizing they were being exposed to carbon monoxide poisoning.

If residents suspect  carbon monoxide poisoning, they should get out of the house or building and air out it out. They should also seek medical attention immediately.

Carbon monoxide alarms, considered a lifesaver

It was a carbon monoxide alarm that saved Jason Cormier's life last week.

The resident of McQuade, about 80 kilometres north of Moncton, lost power after the ice storm, so he set up a generator near a window outside his home, running extension cords throughout the house.

'If we didn't have the alarm I don't know what would've happened to my uncle.' - Jason Cormier

After about an hour, his CO alarm went off, getting him out of bed.

"When I went downstairs, I could smell the fumes, it smelled like exhaust," he said.

Immediately, he ran downstairs, where he woke up his uncle.

The two men then rushed out of the house to shut off the generator. From there, they taped up holes and air ventilations behind the house, where carbon monoxide was getting in, and aired out the house by opening windows.

"It was definitely the generator. It was feeding into the house," he said.

"If we didn't have the alarm I don't know what would've happened to my uncle."

Cormier received the carbon monoxide alarm from his father a few years ago as a gift.

"He said it could save somebody some day," Cormier said. 

"It saved his brother."

Douglas Browne, the fire marshal with the Department of Public Safety, said an alarm doesn`t have to be installed high in a space.

"Just make sure it's in a well-circulated area," he said, suggesting a hallway, outside the bedroom or main areas inside the home. 

How to prevent carbon monoxide poisoning

Carbon Monoxide

If exposed to carbon monoxide poisoning, get out of the house, air it out, call the fire department and always seek medical attention. (Megan Goddard/CBC News)

Blais said it's important to know the hazards of burning fuel, including wood, inside a home.

Appliances such as furnaces, water heaters, fireplaces and wood stoves should have regular maintenance. Ventilation should also be checked, making sure it isn't blocked by snow.

Residents should also buy a carbon monoxide alarm. They can be purchased at any hardware store for about $30.

"There's always a risk," said Blais.

"Monitoring for CO — it's really important."