The old axiom about things that are out-of-sight also being out-of-mind often goes double when it comes to the inner workings of a building’s operating system. The maze of wires, pipes, and ducts is a mystery to the untrained person or board member, but the truth is that what you don't see can definitely hurt you. And what you don't see in the seemingly endless caverns of a building’s HVAC system, for example, can be surprising—from dead rodents and insects to various forms of potentially dangerous mold.
Since it's easy to determine the cleanliness of common rooms such as garbage and recycling areas, these shared spaces tend to get more attention than hidden vents and ductwork does when it comes to keeping things sanitary. On top of the visibility problem, there are no federal or state guidelines that require a building to have its air ducts cleaned.
According to a recent Harvard study, nearly every home tested for indoor air pollution had at least one air quality concern—and most had more than one. The following facts are not pleasant, but they underscore the potential health issues associated with poor indoor air quality. For example, there are 42,000 dust mites living in every ounce of dust. On average, dust mites leave fecal droppings about 20 times a day. When dust is disturbed and goes airborne, it can be inhaled, causing respiratory and sinus distress, and aggravating pre-existing conditions like asthma and emphysema. This is but one segment of possible pollutants. Add mold spores, pet dander and cigarette smoke to the environment and allergens increase exponentially.
“Indoor air is very different than outdoor air,” says Kristy Lee, technical director of Rockville, Maryland-based Indoor Environment Communications. “Indoor air is not circulating or being refreshed so if there is any kind of problem in a building such as mold or dust or anything like that it becomes an irritant, gets worse and keeps getting circulated throughout the building.”
To be clear, however: the Environmental Protection Agency (EPA) finds that there is not enough current research to determine whether or not air duct cleaning definitively prevents health problems. Additionally, studies have not conclusively demonstrated that particulate levels in homes increase because of dirty air ducts. However, the EPA does state that “it makes no sense to clean duct-work if air handlers are left untouched. Air ducts deliver exactly what an air handler drives, and if the duct-work is dirty, so are the air handler’s guts.”