I never thought that it was controversial to suggest that cleaning air ducts is a routine part of HVAC maintenance. I have always had my air ducts professionally cleaned by an HVAC technician from my local HVAC company. I have been doing business with them for almost a decade now, and I trust their experience and expertise. I have read some articles online that suggest that even if your air ducts are filthy, typically any undesirable contaminants, like allergens, mold, and mildew will remain within the air ducts and won’t necessarily blow out into the air you breathe. I find this very difficult to believe. My home has metal air ducts, and I’ve read that the EPA recommends that these kinds if air ducts in particular require cleaning. I still find it hard to believe that if you have mold or mildew or any other dangerous thing in your air ducts that it is not a good idea to have it cleaned out, and that there is no chance that it will end up in the air you breathe, much less permeate it. I’ve heard that other air ducts that are designed with more flexible materials may not need cleaning as often. I think I take the middle road viewpoint: you shouldn’t necessarily completely ignore the kind of stuff that could be festering in your air ducts, although some types of air ducts may need cleaning less often than others. Moreover, above all, I trust the expertise of knowledgeable, certified, and experienced HVAC technicians! The HVAC company I work with hasn’t steered me wrong yet.