Mystified about how they could see, in deep levels, without smoking out everybody above. And, what happens to sewage. Maybe they ventured above ground at night

Mystified about how they could see, in deep levels, without smoking out everybody above. And, what happens to sewage. Maybe they ventured above ground at night to empty the chamberpots? The Egyptians had mile after mile of tunnels, and left no hint of soot on the ceiling.