Hidden Respiratory Dangers at Home

Mycobacterium avium-intracellulare (MAI) and other atypical Mycobacterium can cause a variety of diseases that are on the rise in the US.(2) Patients may present with a productive cough, fatigue, poor appetite, and other nonspecific symptoms. CXR may show some subtle interstitial abnormalities, usually better seen on CT, often some adenopathy, or in more advanced cases, nodules and cavities. Diagnosis is confirmed by more than one sputum culture growing MAI.

Although the cause for the rise in MAI in the US is not known, atypical Mycobacteria can often be cultured in shower heads. In particular, plastic shower head material may be the culprit for the rise in this disease. However, as a disclaimer, Mycobacterium are ubiquitous in the environment, and culturing from showerheads is not proof of causation. Much still needs to be learned about the pathogenesis and epidemiology of this disease before blame can be squarely placed on this one item.

Two-thirds of US families own a pet. . . according to the most recent survey by the American Pet Products Association, up from 56% in 1988. Approximately 60 million American families own dogs, and 47 million own cats. That all adds up to a tremendous quantity of pet dander being shed in US homes. This dander can contribute to asthma in susceptible individuals. Both my wife and daughter developed wheezing after no previous history of asthma after exposure to my cat. Cats may be particularly dangerous because of the constant licking of their fur to clean themselves, unlike dogs, who could care less if they are clean. Cat saliva contains a particularly potent allergen.

For those affected by pet dander, I recommend removal of the pet from the home-a recommendation universally ignored, even by myself! Alternatively, I suggest that the pet be kept out of the bedroom, and an air purifier with HEPA filtration put in bedroom.

Many other indoor allergens can precipitate asthma in susceptible patients. Dust mites are particularly allergenic (actually, it is the feces from dust mites that can become airborne and inhaled.) Dust mites feed on human skin, thus tend to multiply and flourish in areas where human skin can accumulate, such as carpeted floors and bedding. Ways to reduce dust mite exposure include:
1. Wash bedding in hot water
2. Enclose mattress and pillows in special impermeable covers
3. Get rid of carpeting and rugs, particularly in bedroom
4. Keep humidity low
5. Vacuum regularly, remove dust

Other vermin implicated in asthma include rodents and cockroaches, especially in urban areas.

Although I gave showerheads their own category, there are other numerous sources of excess moisture in homes that can lead to serious illness. Water reservoirs, ultrasonic humidifiers, cool mist vaporizers, hot tubs, damp or leaking basements, and poorly ventilated bathrooms all can become growth media for molds, Legionella, and other microorganisms implicated in human illness. Mold is not only a potent inciter of asthma, but can cause a more serious respiratory illness, hypersensitivity pneumonitis.Legionella outbreaks often occur in pool facilities, hotels, and hospitals and can be traced back to water supplies, but can similarly occur in a patient’s own home.

Birds deserve their own category, separate from dogs and cats, because many patients will deny mentioning their birds as pets, unless you specifically ask them. I’ve had patients with birds in their basement, and those who raced and trained pigeons who kept them in their garage, who initially denied keeping them when I asked. Bird allergen can also trigger asthma, but is probably the most common cause of hypersensitivity pneumonitis that I see in my practice. Birds can also be a harbinger and transmitter of infectious diseases, including viruses and psittacosis.

Radon is an inert gas that is a decay product of uranium. It is a definite risk factor for lung cancer in the uranium mining industry, but it is a naturally occurring substance as well, and can accumulate in some areas to measurable degrees in patient homes.(3-5) Some reports have suggested that even low levels of radon are a risk factor for lung cancer, but others have questioned this finding.

Although asbestos has been banned from building materials for at least 40 years, it was used in older buildings for pipe insulation, shingles, and roofing extensively in older buildings. Usually present in very low levels in the ambient air, that can change to very high concentrations if unrecognized and a demolition/renovation of the house is undertaken. Asbestos is a potent carcinogen and can cause a variety of other lung diseases including fibrosis and pleural effusions.