Firstly, I know it's none of my business but this worries me.
I was chatting to my neighbour yeaterday as she was heading off out for a run. She mentioned her 2 year old DS was asleep inside the house (alone). I gently queried how often she left him, to which she replied for half an hour every week day while she runs, as he sleeps reliably and doesn't wake up. I must have made an 'eeek' face as she then (very nicely) explained that mum knows best. I even offered to pop around and sit with my DD in the house while she runs but she thought I was being neurotic.
So AIBU to sit and stare at the house while she runs to check smoke doesn't start poring out?! Or maybe even sit in the garden incase the poor little mite wakes up screaming (although not sure what I could do about that....)