Dirty ducts and HVAC systems can be a breeding ground for mold spores, bacteria, dust, pollen and other harmful deposits. Many different contaminants can accumulate over time. Every day, your family breathes air that is continually re-circulated through this contaminated ductwork. The National Air Duct Cleaners Association (NADCA) recommends to have your air ducts inspected every two years. Depending on your location and the conditions within your home, air ducts need to be cleaned every four to eight years.
You should consider having the air ducts in your home cleaned if there is substantial visible mold growth inside hard surface (e.g., sheet metal) ducts or on other components of your heating and cooling system. “There are several important points to understand concerning mold detection in heating and cooling systems:
Many sections of your heating and cooling system may not be accessible for a visible inspection, so we will show you any mold that we say exists.
You should be aware that although a substance may look like mold, a positive determination of whether it is mold or not can be made only by a mold expert and may require laboratory analysis for final confirmation.
If you have insulated air ducts and the insulation gets wet or moldy it cannot be effectively cleaned and should be removed and replaced by a competent mold remediator.