Do you have dirty ducts? When did you last look? And while regular cleaning of your ducts may be important for your homeowners insurance policy, what might your ducts have to do with your health?
Highly respected authorities on household air quality have studied the relationship between cleaning air ducts and your health. Years ago, the Canada Mortgage and Housing Corporation (CMHC) investigated whether cleaning air ducts leads to healthier air quality in homes, and they concluded it didn’t.
The U.S. Environmental Protection Agency conducted tests that showed, whether air ducts are clean or dirty, virtually the same concentration of dust can be found in the air. This is because dust and dirt tend to stick to the vents and filters, not blow through the air.
However, there are some situations that may give cause for concern. You might think that only old, unkempt farmhouses in rural areas make inviting homes for nasty rodents like rats. But we have seen exponential growth of rat populations in big cities. Homeowners need to make sure there are no compromised vents into the house. Rats, or even smaller pests like cockroaches, when living in your air ducts, can lead to pest-related contaminants that aggravate allergies, asthma, and sinus problems.
Fans that force air through your home can cause condensation inside the duct. Mold can multiple in these places, and then be distributed through the ducts to other rooms. Mold is a culprit in respiratory illness.
If you live in a house that is 50 years old or older, there’s a chance your ducts might be insulated with products containing asbestos. This is a serious problem, and you should call in the professionals and be prepared for a major disruption. Asbestos is associated with lung cancer.
Consider the case of a 33-year-old banker whose chest x-ray showed ominous nodules suggesting he was suffering from lung cancer. The patient refused further treatment on the premise that he was young, didn’t smoke, and his symptom were getting better, not worse.
The banker remained well for a year. But then he began to experience the same symptoms, complaining of fever, coughing, body aches and shortness of breath. An X-ray showed a recurrence of the conditions suggesting cancer. But after several weeks, his symptoms mysteriously vanished again.
This prompted his doctor to send the patient to Dr. Robert Rubin, an infectious disease expert at the Massachusetts General Hospital. Rubin noted that X-rays showed the lesions in the lungs were always in different locations, hardly what one would expect with a malignancy.
Dr. Rubin’s diagnosis was “Hypersensitivity Pneumonia”. But what was causing his symptoms and the disappearing lesions in the lung?
Hypersensitivity pneumonia occurs when the lungs become inflamed from dust laden with mold, fungi and spores. The most common culprit, thermophilic actinomycetes, which decomposes leaves, bark and plant materials. This is why farmers suffer from “farmer’s lung”. There’s also “wine grower’s lung” due to moldy grapes, “crack lung” from heavy use of crack smoking, and “bird farmer’s lung” from feathers and bird droppings.
But bankers don’t harvest sugar cane, cure tobacco, work with wood dust, soybean feed, barley or mushrooms.
Dr. Rubin then became as much a detective as a doctor. He questioned the patient about humidifiers, his hobbies and home heating system. Finally he got a clue. The banker’s symptoms began when his bank moved into new office space. Rubin discovered the building’s ducts had been blown clean twice. It was on each of these occasions that the patient had developed symptoms and cancer-like lesions of his lungs.
But Rubin, still in detective mode, took swabs from the ducts, particularly from wet areas. Analysis showed the culture was loaded with actinomycetes.
But why didn’t other workers develop hypersensitivity pneumonia? Rubin believes it depends on the severity of exposure and a person’s genetic predisposition.
Following cleaning of the ducts the banker worked in the building for another four years without any more attacks.
Today I wonder how many doctors would put on work clothes and examine ducts? More likely, you will need to do your own detective work. Know when it’s worth disturbing your ducts, and when to just leave them be.
Dr. W. Gifford-Jones can be reached at firstname.lastname@example.org