In the context of IAQ, what is meant by "fresh air"?

"Fresh air" in the context of Indoor Air Quality (IAQ) refers specifically to unpolluted outdoor air brought indoors. This definition emphasizes the importance of sourcing air from outside environments that are free from indoor pollutants, allergens, and other harmful substances.

Bringing fresh air indoors can help dilute indoor contaminants and improve overall air quality. This concept is essential for maintaining a healthy indoor environment, as it helps to reduce the concentration of indoor air pollutants that can originate from various sources such as building materials, furnishings, and occupant activities.

The other options touch on different types of air manipulation and treatment but do not capture the essence of what fresh air means in the context of IAQ. For instance, air that has been filtered multiple times refers to processed air that may still originate from an indoor environment. Artificially cooled or heated air does not necessarily ensure the absence of pollutants since it could still originate from a compromised indoor atmosphere. Capturing air from indoor spaces would likely involve air that is already polluted, failing to meet the criteria for being considered "fresh." Hence, fresh air is fundamentally about bringing clean, outdoor air into indoor spaces for better air quality.