It’s a question of pressure, really, and of cumulative effects. The manner in which households of yore kept their homes warm without choking on the smoke was to instal a chimney, the pressure difference created by the hot column of gases creating draught and pulling air over the coals or the firewood, keeping it burning while also chasing the smoke away. Naturally the soot adheres itself to the walls of the chimney over time, reducing its efficiency and also posing a risk of combustion. It’s an elegant scientific process that also brings with it a frisson
