The National Air Duct Cleaners Association (NADCA) says that “through normal occupation in a home, we generate a great deal of contaminants and air pollutants, such as dander, dust, and chemicals. These contaminants are pulled into the HVAC system and re-circulated 5 to 7 times per day, on average. Over time, this re-circulation causes a build-up of contaminants in the duct work.

While dirty ducts don’t necessarily mean unhealthy air in your home, school or workplace, they may be contributing to larger health issues or harbouring contaminants that could cause serious problems for people with respiratory health conditions, autoimmune disorders or some environmental allergies.”