Keith Tremblett got a nasty surprise when he started renovating his family's old home in Colinet, St. Mary's Bay.

It wasn't the usual culprits — rotting foundations, leaky roofs, or substandard plumbing.

He found a gasket, which acts as a heat shield inside the furnace, had deteriorated until it was almost gone.

Replacing it would have been easy for Tremblett, who has worked as a mechanic for over 20 years. But he hesitated.

"In the process of taking it apart and doing the repairs, I was looking at the gasket and I was saying, ‘Jeez, I wonder what material that's made out of, and should I be concerned here with what I'm dealing with?’ " he recalled.

So he contacted the manufacturer, Newmac Furnaces.

The Nova Scotia company told him, given the age of the unit, the gasket likely contained asbestos and should be replaced.

"All I found was remnants of it," he said. "It's not even a full sheet anymore. It's just remnants of the gasket and most of the material, I would have to assume, is either within the ductwork or throughout the house."

If released into the air, microscopic asbestos fibres can travel into the lungs. Over time, that can lead to asbestosis — which impairs lung function, and is incurable — or a number of deadly cancers.

Tremblett says the manufacturer simply told him to remove the gasket.

"I think they handled it truly unprofessionally," he said. "Their recommendation to me was to wet it down and remove it."

Health Canada banned asbestos use in furnaces in the early 1980s. But there was no recall — not even a public warning about the potential danger.

Today, three decades later, that's still a worry. The lifespan of a furnace is 50 years or more.

Janet O'Reilly has been repairing furnaces for more than 30 years, and now teaches the trade at the College of the North Atlantic in Seal Cove.

"There could be quite a few furnaces out there that do have asbestos," O’Reilly told CBC News.

"But like I said, as long as contained, as long as it's in good condition, asbestos is not a health or risk factor to the homeowner or to the people working on the system. It becomes an issue when it’s disturbed."

And that's exactly what Tremblett believes happened with his furnace.

"These furnaces are still in use, and when this breaks down this is going to be circulated throughout the house," he said.

"It’s in a bad location. It's not like it's in your home, in a wall or something and it’s undisturbed. It's disturbed. It's got a blower acting on it."

Tremblett spent months looking for information on the affects a deteriorating gasket would have on human health.

He turned up nothing that addressed his fears.

Neither did efforts by CBC News to do so.

One of America's leading experts on the effects of asbestos exposure, Dr. Barry Castleman, was not aware of any research in this area.

But he conceded that failure of an asbestos gasket in a furnace of this type could lead to long-term exposure.

"Well, that is worrisome," Castleman said. "If I had that in my house I'd feel concern about that, because the material will deteriorate with enough time and heat.

"At the same time, you don't want to panic people and have them start to ripping these things out."

O'Reilly, meanwhile, agrees the gaskets can break down over time, especially in damp environments like this province. Long periods when the furnace is not operating can accelerate that deterioration.

But she says the most likely scenario is that chunks of the gasket would fall away inside, and not be slowly released into the air inside the house.

Hot-air furnaces are by far the most popular way to heat a house in Canada. Millions have been sold over the years.

According to Statistics Canada, they comprised 56 per cent of the market in 2007.

There's no way to know how many older furnaces containing asbestos may still be in operation. Or if that asbestos is breaking down.

O'Reilly says it's best to play it safe.

"I'd have a qualified person come in and look at it," she said. "If they think that yes, you could have asbestos products, they should be able to tell you that. They should be able to minimize the risk factors by making sure it's in good condition and letting you know.

"And if they don't, they can always turn the furnace off and say you shouldn't use it until this is taken care of."

Health Canada says it's regulated the use of asbestos in Canada since the late 1970s, but that no warnings or alerts have been issued on this specific issue.

Nor did it conduct any studies to determine if this problem can lead to long-term asbestos exposure.

Instead, Health Canada says the effects of asbestos exposure are well known and available on its website.

Health Canada also urged anyone who suspects their furnace contains asbestos to have it inspected by a qualified technician.

That response is not enough for Keith Tremblett. He thinks Health Canada should take some responsibility.

Tremblett now plans to replace the heat shield with one that doesn't contain asbestos. He will also get an asbestos abatement company to thoroughly clean the house and its heating system.

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