Reducing the dust in your home may be a logical reason to clean your air ducts however, after reviewing an article written by The U.S. Environmental Protection Agency (EPA), it raises the suspicion that air duct cleaning may be a deceiving tactic carpet cleaners use to lure consumers into thinking it's causing an unhealthy living environment.
To summarize, The EPA does not recommend that the air ducts be cleaned routinely, but only as needed. However, the EPA recommends regular cleaning the air filter at your furnace. We suggest checking this filter in early October on an annual basis. If you have central air conditioning, we suggest a check in April as well. PG&E offers this filter inspection/change as a free service to their customers; if you need help, just call them and request an appointment.
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. Moreover, there is no evidence that a light amount of household dust or other particulate matter in air ducts poses any risk to your health.
Some research suggests that cleaning heating and cooling system components (e.g., cooling coils, fans and heat exchangers) may improve the efficiency of your system, resulting in a longer operating life, as well as some energy and maintenance cost savings. However, little evidence exists that cleaning only the ducts will improve the efficiency of the system.
Based on this information we recommend any work done on your HVAC system or Air Ducts be performed by a licensed HVAC company and not a carpet cleaner!