The proliferation of high-rise condominiums has made the job faced by firefighters increasingly difficult, warns Toronto's retiring fire chief.

Bill Stewart made the comments to Stephen LeDrew on Thursday afternoon as he prepared for his last day on the job on Tuesday.

"It is a huge factor. We are number two in North America for residential high-rise buildings and the reality for us is that anything above six stories is strictly interior firefighting," Stewart said. "We have what we call a vertical response time. We pull up to the front door, we have to move the equipment in and then you have to add on whatever time it takes to get to the fire floor."

Stewart originally became a firefighter in the former City of North York in 1972 and has led Toronto Fire Services since 2003.

He said throughout his career virtually all of the most dangerous blazes he has presided over have been in high-rise buildings.

"If you look at the most dangerous incidents (in my career) they are all high-rise fires because of smoke migration," he said. "We have in theory fire doors or exit doors which are supposed to be closed, but in many cases they are not, and as a result smoke begins to move through the structure compromising your means of escape. Stairwells become chimneys."

Though Stewart will retire from active duty Tuesday, he told CP24 he will still be actively involved in fire prevention as a member of the board of directors for the Institution of Fire Engineers in the United Kingdom and the National Fire Protection Association in the United States.

"I'm certainly not going to be sitting around or anything," he said.