Duct cleaning has never been shown to actually prevent health problems. Neither do studies conclusively demonstrate that particle (e.g., dust) levels in homes increase because of dirty air ducts. This is because much of the dirt in air ducts adheres to duct surfaces and does not necessarily enter the living space.

Cleaning air ducts every three to five years is important to ensure the system is running at capacity and can reduce dust and mold in the home. According to Fourner, benefits of cleaning air ducts include: Gets rid of dust mites and reduces allergies and asthma issues.

The best times to have your ducts cleaned is either in the spring or in the early fall, after you have stopped using your HVAC system to cool or heat your property and before you need to start using it again. You have likely experienced that dusty or musty smell when turning on your HVAC system.