Prior to mechanical ventilation, how was fresh air typically provided in buildings?

Fresh air in buildings prior to the advent of mechanical ventilation systems was primarily acquired through natural means such as opening windows or allowing for accidental infiltration from outside. This approach relied on the natural movement of air and environmental conditions to bring fresh air into interior spaces.

Opening windows allowed occupants to control their indoor air quality by increasing ventilation when needed, like during warmer months or in mild climates. Additionally, buildings were often designed with certain airflow pathways that allowed air to enter through openings or around structural features. Accidental infiltration also contributed as buildings, especially older ones with less airtight construction, would allow outside air to seep in through cracks and openings.

This method of providing fresh air had its limitations, including variability based on weather conditions and potential outdoor pollutants, but it was the primary way to ensure air circulation before mechanical systems became commonplace. Other options like mechanical systems and air purifiers focus more on actively filtering or controlling air quality rather than facilitating the natural exchange of air that is indicative of fresh air provision.