Before steam engines and electricity in the 1800 created the conditions for the effective operation of the fans, the best way to avoid tainting indoor air was to either air vent or create drafts by heating the air in the stoves/fireplaces, air which then left the building via chimneys or towers (nowadays known as stack effect). This happened when an under pressure occurred based on pulling in fresh air through leaks in particular, walls, doors and windows. We can call it the events of the fire-driven ventilation that is simply based on the principle that hot air rises.
Certainly, the hand-operated wood fans and others had begun to be used in some buildings already in the mid 1700s, but only in small scale because they had an obvious disadvantage; they required major efforts. Just for example to vent Queen Victoria’s opera loge in London demanded two people.