How can mechanical ventilation improve indoor air quality?

Mechanical ventilation improves indoor air quality primarily by filtering harmful particles from the air. This ventilation system actively draws outdoor air into the building while also expelling stale indoor air. Equipped with filters, mechanical ventilation systems can capture dust, pollen, allergens, and other contaminants that exist in both indoor and outdoor environments. As a result, the air circulating within the building maintains a higher standard of cleanliness, which is vital for the health and comfort of occupants.

The other options do not directly contribute to improving indoor air quality. Cycling air with a constant temperature doesn't necessarily correlate with filtering out contaminants, and while it may help maintain comfort, it does not inherently enhance air quality. Eliminating outdoor noise is a benefit that may come from sealed windows but is unrelated to the cleanliness of the air itself. Finally, reducing the need for window openings might assist in maintaining controlled temperatures and consistent airflow, but it does not itself filter or clean the air. Thus, the primary and most direct mechanism by which mechanical ventilation improves indoor air quality is through the filtration of harmful particles.