I've been feeling light-headed and woozy and finding it hard to focus lately, so I stopped taking my medicine that helps me focus (just to see what my baseline is) and... it didn't help and I felt the same.
So at the urging of a friend, I got a CO2 monitor to check the air quality in the house.
400 ppm is outdoor quality air. My house apparently idles at around 700-800 overnight which is pretty good.
Oh, I wonder what happened at 12:37 today? ...we turned on our gas oven and the air quality two floors up got obliterated.