Which action most effectively improves Indoor Air Quality?

• A. Source control
• B. Air cleaners
• C. Improved ventilation
• D. Humidity control

Answer: (A)

Reducing or preventing pollutant sources is the most effective way to improve Indoor Air Quality because it stops contaminants before they enter the air, rather than trying to remove them after they’re present. By controlling sources, you lower the total amount of pollutants generated, which leads to larger and longer-lasting improvements. This includes choosing low-emission materials, sealing leaks and using products with low VOCs, preventing indoor smoking, maintaining moisture control to avoid mold, and ensuring proper ventilation design that doesn’t introduce new contaminants.

Air cleaners can remove pollutants that are already in the air but don’t prevent emissions and require ongoing maintenance. Improving ventilation dilutes indoor air with outdoor air, which can bring in outdoor pollutants or raise energy use if not well managed. Humidity control helps reduce moisture-related problems like mold and dust mites but doesn’t address other pollutant sources. Because it tackles the source of contaminants, source control yields the most effective overall improvement.