We won't know what he died of until the autopsy, but if he climbed down it's likely he died of "
positional asphyxia," a condition in which the contortion of your body prevents the normal in-and-out motions of your diaphragm.
In other words: if you don't get out of that position, you're going to die from lack of oxygen. And, in a chimney, there's not enough room to get out of that position. "
positional asphyxia," a condition in which the contortion of your body prevents the normal in-and-out motions of your diaphragm.
And, in a chimney, there's not enough room to get out of that position.
So that means he could've been dead with 15 minutes of climbing in the chimney.