Air duct cleaning's effectiveness depends on the methods used, the cleaner's expertise, and the severity of contamination. Professional cleaning by NADCA-certified technicians using proper equipment demonstrably reduces dust, allergens, and other airborne particles, improving indoor air quality and HVAC efficiency. However, duct cleaning is not a cure-all for allergies or respiratory issues and should be part of a comprehensive indoor air quality management plan. Combined with these practices, cleaning can effectively enhance indoor air quality.