Dust, grime, and debris can accumulate faster than you'd imagine. With air constantly flowing through your ducts, that means so are micro particulates that begin to buildup the moment your ducts are clean.
Even with air purification systems installed in the house, ductwork is recommended to be cleaned every 3 - 5 years (more depending on your home and location).
If you're unsure if your ducts need cleaning, contact a First Call Jewel specialist for a consultation.