When a certain family rugrat was small I caught her playing by a toilet. Her mother thought me paranoid when I told her of the kids who died each year from pitching in headfirst and drowning.
In fact, it can even happen in a bucket. The kids are so topheavy that if they go in head first and there's enough water in the bowl, that's it - they're not likely to be able to get themselves out. They won't even be able to scream for help. And Mom would only have to be out of the room for a couple of minutes...
And now we read this. At least it wasn't a toilet, but this would be worse. With a little imagination it becomes Poe-like - slowly getting wedged in a little farther with every exhalation, possibly over hours, until breathing became impossible.
Maybe I've been scarred by my nuclear power days, which I spent mostly looking for things that could go wrong and what could be done about them. Or maybe it's remembering a house that I lived in as a kid - the heater that always made my mother nervous while we lived there eventually started a fire that burned it to the ground. But the fact is that this is the time of year that lots of people die at home in ways they probably never gave a second thought to.