Dark Side of the Fireplace

This is why the kitchen is not quite a rectangle. I'm going to tear down all this drywall, but I gave a little test tear to check things out. This is the back side of the chimney. It's dark, though these days the front side is dark, too. That's because we pretty much stopped having fires several years ago because of the particulate pollution they produce. I became more aware of that after visiting Yellowstone NP and reading about the problems they were having from campfires some times. Of course, even if we wanted to have fires, we frequently couldn't because the local air quality district realized the same thing, and passed regulations limiting when people can have fires, and only EPA-certified inserts, wood stoves, etc. can be installed in new construction. Glass doors I installed many years ago plus the damper keep it from sucking too much warm air out of the house, but the fireplace sits dark.