[snrplfth]

Haha. They breathed tons of fumes, most of their households' cooking and heating was fueled with either wood, charcoal or dung, in open or not-well-sealed hearths. (Woodsmoke is still the world's deadliest source of pollution.) Roman cities especially were ferociously polluted.

[alexasmyths]

If there is a stove-pipe then they are not breathing any fumes.

[snrplfth]

A lot of stovepipes leak fumes, an in any case most people in the Roman empire had no such thing as a stovepipe. It's absolutely a myth that most premodern people had "clean air". No, it was generally filled with smoke, dung dust, mold spores, etc.