Modern homes can go up in flames even more quickly than older ones, and leave little time for residents to get out safely, according to an Ottawa fire safety expert.

"People do not understand how fast fire moves today. They have a misconception that they have enough time, that the smoke detector will provide enough time for them to get out," said Peter McBride, a firefighter and safety expert with the Ottawa Firefighters' Association.

"There [have] been numerous occasions where I have attended fires, [and] people have tried to go back in to get a dog or, as you can well imagine, a loved one. It's a very tough call, but the reality is they generally don't survive," McBride told CBC News.

McBride cites a study of smoke alarms by the U.S. National Institute of Standards and Technology in 2004, in which the institute found people had as few as three minutes to flee a fire under certain conditions, a substantial reduction in time compared with a 1975 study.

“The three-minute escape window for flaming fires differs from the 17 minutes NIST recorded in its seminal smoke alarm tests in the 1970s,” said Richard Bukowski — the NIST researcher who conducted both studies — in 2004.

“It confirms what fire scientists have recognized for some time: fires today seem to burn faster and kill quicker because the contents of modern homes (such as furnishings) can burn faster and more intensely," Bukowski said.

"Plastics have replaced the metal, have replaced the stone, and in some cases replaced the wood, and these materials are all over the house," said McBride.

He also said toys once made of metal or wood are now made of plastic.

"My kids play with plastic every day — Lego, the fitness balls."

Modern furniture presents another risk, he said.

Forty years ago, furniture stuffing was made of dense cotton or wool, which tended to smoulder. Now, it's usually made of foam, he said.

"It's like gelled gasoline, essentially, and starts to flow around," and spread fire to the house, which also contains a lot of plastic.

"The materials that were used in the 1950s were metal claddings, full wood siding or brick. Today, we have vinyl, other plastic products on the exterior of the structure," McBride said.

'We all came running': homeowner

Ottawa's David Glasberg has personal knowledge of the speed with which fire spreads. He is still picking through personal treasures in the rubble of his home that burned down last winter.

It was New Year's Eve, just before midnight, when he was alerted by the screams of his 10-year-old daughter, Stacey.

"We all came running. When I saw the [Christmas] tree, it was pretty much on fire, and instinctively, I pretty much knew I didn't have time to do anything," Glasberg said.

His family got out just in time to see the house burst into flames.

"Within two minutes the lights were gone, the smoke was really intense and heavy — hard to breathe — so you know it could have been a lot worse had we been upstairs asleep."

While the number of people who die in house fires is declining in Ontario, the fires themselves are burning faster than ever, McBride said.

Fatalities in residential structures in Ontario declined from 119 in 1997 to 73 in 2006, according to statistics gathered by the Office of the Ontario Fire Marshal. The reduction in the number of fires, and in the number of fatalities is due in part to the widespread use of smoke alarms, and also the result from many people quitting smoking.

McBride said that reduction has lulled people into not paying attention to warnings about how rapidly fires can spread in modern homes.