The answer to 'why is my air duct filthy' is that air ducts can become dirty over time due to a buildup of dust, dirt, pet hair, and other airborne particles. This can be caused by factors like poor indoor air quality, infrequent cleaning, and inadequate air filtration. Symptoms of a dirty air duct system include reduced airflow, increased dust and allergens in the home, and higher energy bills.
To address a dirty air duct, you have a few options. For minor buildup, you may be able to do some basic DIY cleaning by vacuuming out the visible dust and debris. However, for more significant or hard-to-reach areas, it's best to hire a professional air duct cleaning service. They have the specialized equipment and expertise to thoroughly clean the entire duct system and restore proper airflow.