Every home and business is different. Many factors influence the hygiene levels of your HVAC duct system including the type and frequency and proper maintenance of filter maintenance, A/C component maintenance frequency (evaporator coils, blower motors, pan treatments, etc), duct leakage, humidity levels and structure location, to name a few.
How often should they be cleaned?
The frequency of cleaning depends on many factors within the building. These 6 main factors are among a few to consider:
1- Renovations/Remodeling
2- Flood or water contamination
3- Allergies
4- Pets
5- Smoking
6- Moving into a new home
For best preventive measures, minimally, your A/C system should be inspected yearly and ductwork inspected every 2 years.