Indoor Air Quality (IAQ) Practice Exam 2025 - Free IAQ Practice Questions and Study Guide

The primary function of a mechanical exhaust system is to actively extract indoor air contaminants. These systems are designed to remove stale air from indoor environments and help reduce the concentration of pollutants, such as volatile organic compounds (VOCs), odors, and other harmful substances. By pulling air out of the built environment, mechanical exhaust systems promote better indoor air quality by facilitating the exchange of indoor air with fresh outdoor air, thereby lowering the levels of various contaminants that could negatively impact health and comfort.

In contrast, other options pertain to different functions. Circulating air within a building is typically the role of a mechanical ventilation or air distribution system rather than an exhaust system. Filtering allergens from the air is more related to air purification systems that involve filtration methods, while humidifying the indoor environment refers to systems designed to add moisture to the air, which is not the primary role of an exhaust system. Therefore, extracting indoor air contaminants is the definitive purpose of a mechanical exhaust system, underscoring its significance in maintaining a healthier indoor environment.