me too, but I was in my 20's...
I lived in a small cottage my family called a "hovel." Ice would form on the inside of the house along cracks in the plaster on cold days. My roommate insisted on using a Kerosene heater in this place.
One winter afternoon I was relaxing in a hot bath with the heater going in the other room. I was more sleepy in the tub than normal. I barely got out of the tub and staggered into the living room. The world went all blurry, then black, and I fell to the floor. I managed to crawl, naked, to the front door. I opened it and crawled into the cold air, saving my life. I instantly felt better. Death was close that day.
I use a kerosene heater now in the garage, but that garage is a sieve, so I'm not concerned there - it gets plenty of O2.