March 20, 2018 -- As spring allergy season approaches, you may hear companies make bold promises to improve your health by reducing allergens in your home. Such boasts may appeal especially to the nearly 25 million American adults and children with asthma and the approximately 50 million who have allergic rhinitis, or hay fever, because the symptoms of both can be triggered by dust mites, mold, and other allergens often found in air ducts and elsewhere in the home. Allergies, according to the CDC, are the 6th leading cause of chronic illness in the U.S.
But should you believe the hype? Will air duct cleaning help you breathe more easily?
“There’s never been a great study that shows objective evidence of disease improvement (as a result of air duct cleaning),” says allergist Anthony Montanaro, MD. “But to me, it’s always been a commonsense move. If you’re sensitive to what’s found in dust, it’s to your best advantage to minimize exposure to it.”
Montanaro, a professor of medicine and chief of the allergy and clinical immunology division at Oregon Health and Science University in Portland, often talks with patients about their heating systems as he investigates the possible environmental triggers of their allergies.
“If they have forced air, that’s part of the conversation,” he says.
Heating, ventilation, and air conditioning (HVAC) systems push air through ducts that run throughout your house in walls, ceilings, and floors. Mark Zarzeczny, who sits on the board of directors of the National Air Duct Cleaners Association (NADCA), calls ducts the "lungs of the home."
How can you tell whether your air ducts need attention? Visual clues, like signs of mold and excessive dust around the air vents, can point to a need for cleaning. But when there’s no evidence in plain view, allergist Tania Elliott, MD, advises people to ask themselves the following questions:
- If your house is more than 10 years old, have your ducts ever been cleaned?
- Does your house constantly collect dust no matter how much you clean it?
- Do you notice allergy symptoms when you turn on your heating/cooling system?
- Do you have asthma that’s not well controlled even though you’re taking your medicine?
Answering yes to any of these questions should encourage you to consider cleaning your ducts.
“It’s better safe than sorry for people who have underlying asthma or allergies or breathing issues,” says Elliott, a spokesperson for the American College of Allergy, Asthma and Immunology and chief medical officer of EHE International, a healthcare management company that focuses on preventive medicine.
The Cleaning Process
Before cleaning begins, identify the source of the problem. Mold, for example, likely means a buildup of moisture somewhere in the system. If you don’t correct that problem before cleaning, the mold will return. In the case of dust, poor air filtration may be to blame. Critters like mice and cockroaches also can contribute to debris in your air ducts. You’ll want to learn how they get in and plug up any entry points before you clean. Some underlying problems can be addressed by an air duct specialist, says Zarzeczny, while others may require the services of a different professional.
Once the underlying cause has been addressed, the cleaners can get to work. After they seal your system to prevent dust, mold, insects, animal droppings, and other muck in the ducts from escaping into your home, they use high powered vacuum cleaners and other tools to dislodge and remove debris. The entire HVAC system should be cleaned.
“The equipment used depends on the nature of the debris and what the duct work is made of,” Zarzeczny says.
He also says that some cleaning may require the use of chemicals such as pesticides to kill mold and other potentially harmful microbes that may be found in your air duct system. Before you agree to the use of such chemicals, have samples of suspected mold verified by a laboratory, which the Better Business Bureau says will cost about $50. Do not rely on in-home or other types of tests, advises the EPA.
Other types of chemicals include degreasers, deodorizers, sealants, and more. Review the chemical’s label, which will explain its EPA-registered uses and any health risks associated with it. Deodorizers, for example, may trigger headaches, asthma attacks, and allergies. You and your pets may need to vacate your house during and after cleaning.
“Only a small number of chemicals have been registered with the EPA for use in HVAC systems,” Zarzeczny says. “They should not be used arbitrarily and used only on non-porous surfaces.”
There are companies that advertise "green" or "eco-friendly" duct cleaning. At least one says it uses a non-toxic disenfectant made from thyme, rosemary and other herbs. But Zarzeczny urges consumers to be cautious about such claims.
"I have personally dealt with companies that claim to be green," he says. "They don't have any paperwork to identify what the chemical is and some recommend applying more than one during the duct cleaning process at one time. It is not wise to arbitrarily create a mix of chemicals."
Time, Cost, and What to Avoid
Zarzeczny says a typical job on a 2,000-square-foot home will take about 3 to 5 hours and should be done every 3 to 5 years or if the signs described above return. Expect to pay at least $500 to $600.
“Anybody who offers to do a job for less than a few hundred dollars is not going to deliver to you what you need to have done,” says Zarzeczny, who chairs NADCA’s anti-fraud task force. “You don’t want a company that advertises at prices like $79.95 because they’re either going to be in and out in half an hour or they’re going to upsell you and walk out with $4,000.”
In fact, a rushed, inadequate job can do more harm than good. According the EPA, “an inadequate vacuum collection system can release more dust, dirt, and other contaminants than if you had left the ducts alone.”
So before you hire a service, do your homework about the companies you’re considering. Read customer reviews on reputable websites, look for NADCA certification, check their standing with your local government’s consumer affairs department or Better Business Bureau, and be sure they hold the proper licenses required in your state.
While ductwork can’t be cleaned without specialized tools, Zarzeczny says homeowners can slow down the accumulation of debris by keeping vent covers clean and checking and changing air filters often.
Also, try to reduce the likelihood that allergens will accumulate in the first place. For example, Elliott recommends that you keep your house below 50% humidity. “If it’s higher than 50%, you’re at risk for dust mites and mold,” she says.
Be aware of other potential sources of allergens as well, such as carpets, upholstered furniture, gas and wood-burning stoves, and pets.
“It’s almost never an air duct issue in isolation,” Montanaro says.