National Air Duct Cleaners Association (NADCA) Practice Test

Verification after cleaning should combine what you can visually assess with objective measurements to confirm cleanliness. Using static pressure or air velocity measurements provides numerical evidence of how airflow behaves through the system and helps detect any remaining obstructions or imbalances that visuals alone might miss. When these measurements are taken in addition to post-cleaning visual inspection, borescope imagery, and thorough documentation, you get a solid, data-supported confirmation that the ducts are clean and performing as intended. Odor testing by itself isn’t sufficient to prove cleanliness, and relying only on visuals or borescope footage can miss hidden debris or flow issues. The measurements add the quantitative check that complements the qualitative observations.