Asthma and Mold Exposure Risk

by Eli Hendel, M.D. Medical Reviewer

A patient shares that he noticed “there was mold in the walls of his house or workplace,” and he developed symptoms of cough and congestion. His sputum sample is read by the lab as “presence of yeast.” Mold caused his symptoms, right? Not exactly.

What are molds?

Molds are microscopic fungi that live on plant and animal matter. Mold is found anywhere, especially when moisture is present. Molds can begin growing indoors when the spores land on wet surfaces. That’s why mold is common in basements, bathrooms, and laundry rooms. Mold spores can also exist in fabrics, carpets, stuffed animals, books and wallpaper. So mold is pretty much everywhere.

How do we prevent mold exposure and is it toxic?

The best way is to control our environment and minimize exposure. If all exposure to mold was toxic, there would be more disease evident. When disease related to mold does occur it’ usually not in the form of infection (as is commonly believed) but rather as inflammation in allergic individuals and those with hyper-reactive airways. Breathing mold spores in large concentrations can trigger an asthma attack, though not necessarily in all patients with asthma. Only asthma patients sensitive to molds will have an asthma attack.

Is there any benefit to molds?

Molds also play a very beneficial role. They can be the source of enzymes used in medicinal products. One species, Aspergillus Niger, is the largest source of citric acid. Other molds are used for fermentation of alcoholic beverages and some molds are used in the production of sour breads.

How do you know if you are sensitive to molds?

It is important to identify those who are sensitive to molds. This can be done with a blood test that measures the level of immune protein in the blood, IgE (immunoglobulin E) to see if it is significantly elevated. First we measure the total amount of IgE and then we measure for specific antibodies to specific molds.

If I am mold-sensitive, what can I do to limit symptoms?

For those individuals who are sensitive and reactive to mold, it’s important to take measures to control the indoor environment, especially the humidity level. Indoor humidity levels should be maintained to less than 50 percent and ideally at or below 30 percent. A dehumidifier can keep the air drier, thereby keeping mold spore levels reduced. It’s also important to change the filters in air conditioners, clean the exhaust fan after taking showers, minimize the damp clothes or towels in open hampers, clean curtains, and use high efficiency particulate air filters (HEPA filters) to remove mold from the air. Also focus on basements, garages, and outdoor areas of the house that are susceptible to dampness and spore accumulation.

If I do all that will I completely prevent mold?

Even that will not completely eliminate the possibility of disease. One of the most important molds that cause disease is Aspergillus Fumigatus. It grows in oxygen-rich environments, so it’s commonly found in the lungs. That’s why it’s often found in individuals with COPD and tuberculosis, lung diseases that result in stagnation of air and poor air movement in the airways. Finding aspergillus in lung secretions does not necessarily correlate to symptoms, and does not necessitate treatment.

When does a diagnosis of aspergillus in the lungs require treatment?When there is an excessive inflammatory reaction to the fungus that results in airway destruction, treatment is warranted. This condition can happen in asthmatics and is called Allergic Bronchopulmonary Aspergillosis (ABPA). It requires treatment with steroids (not antifungal medication). The steroid helps to prevent permanent destruction of the bronchi and resulting bronchiectasis.

Why was I given antifungal medication with this diagnosis?There are situations where it is important to use antifungal medications (antibiotics against fungi). Patients with poor immune function, patients taking steroids long term, and patients who receive organ transplants and are taking immune suppressing agents are at high risk for proliferation of the spores. Invasive Apergillosis can then occur. To prevent this dire condition, the use of antifungal medication is warranted. Mycetoma is another situation where the fungus can solidify into a cavity of the lung, without actually causing symptoms. It is often seen on X-rays and viewed with alarm, but patients are usually symptom-free.

Of course, everyone benefits from limiting moisture in the home and keeping a relatively clean environment, which will limit mold.

Eli Hendel, M.D.
Meet Our Writer
Eli Hendel, M.D.

Eli Hendel, M.D., is a board-certified internist/pulmonary specialist with board certification in Sleep Medicine. An Assistant Clinical Professor of Medicine at Keck-University of Southern California School of Medicine, and Qualified Medical Examiner for the State of California Department of Industrial Relations, his areas include asthma, COPD, sleep disorders, obstructive sleep apnea, and occupational lung diseases. Favorite hobby? Playing jazz music.