Identify three indicators of an indoor air quality (IAQ) problem and a corresponding remediation action.

• A. Persistent odors/irritation — increase ventilation; Elevated CO2 levels indicating poor ventilation — implement source control; High PM or VOCs — upgrade filtration.
• B. Persistent odors/irritation — improve filtration; Elevated CO2 levels indicating poor ventilation — increase ventilation; High PM or VOCs — use chemical scrubbers.
• C. Persistent odors/irritation — increase ventilation; Elevated CO2 levels indicating poor ventilation — increase ventilation; High PM or VOCs — upgrade filtration.
• D. Persistent odors/irritation — ignore; Elevated CO2 levels indicating poor ventilation — implement source control; High PM or VOCs — upgrade filtration.

Answer: (C)

Persistent odors or irritation, elevated CO2 levels, and high PM or VOCs are clues that indoor air quality isn’t meeting comfort and health needs. The best way to address each is to tailor the action to how the contaminant affects the air: odors and irritants are often reduced most quickly by bringing in more outdoor air to dilute them, so increasing ventilation helps clear those smells and irritants from the space. Elevated CO2 serves as a tracker of ventilation adequacy; when CO2 climbs, it means the room isn’t exchanging air quickly enough, and increasing ventilation fixes the root by flushing the space with fresh air. For high particulate matter and volatile organic compounds, upgrading filtration directly removes many of these contaminants from the air that’s circulating, reducing exposure to particles and adsorbed VOCs.

In short, odors and irritation respond well to more ventilation, CO2 levels improve with better ventilation, and high PM/VOCs are effectively addressed by better filtration. This combination aligns actions with how each indicator impacts indoor air.