Mold in Lungs: Asthma, Aspergillosis and Who's at Risk

Mold spreads by releasing spores into the air, and you breathe them in all the time. The CDC says Aspergillus spores are common indoors and outdoors and that most people breathe in Aspergillus spores every day without getting sick. A healthy immune system clears them.

Problems happen in three ways, according to a position paper from the American Academy of Allergy, Asthma & Immunology (AAAAI): mold can cause a harmful immune response (eg, allergy or hypersensitivity pneumonitis), direct infection by the organism, and toxic-irritant effects. For the lungs, the first two matter most.

Table: lung conditions linked to mold, and who is mainly at risk.

Asthma is by far the most common way mold affects the lungs.

• The CDC says breathing in mold can trigger an asthma attack whether or not you are allergic to mold.
• The NIEHS says mold exposure can increase a person's risk of developing asthma or worsen its symptoms, particularly in young children.
• The CDC says people with asthma or mold allergy may have severe reactions.

The evidence here is solid. The Institute of Medicine's 2004 review for the CDC found sufficient evidence linking damp indoor spaces to cough, wheeze and asthma symptoms in sensitized people, and limited or suggestive evidence for asthma development. The World Health Organization similarly found the most important effects of damp, moldy buildings are increased prevalences of respiratory symptoms, allergies and asthma.

The CDC's asthma advice for mold is practical: dry damp or wet items within 24 to 48 hours, fix leaks quickly, keep humidity under 50% and check it with a hygrometer, and run the bathroom fan when showering. A dehumidifier helps in humid parts of Texas. If you're allergic to mold, our mold allergy guide covers testing and treatment.

The CDC says aspergillosis is an infection caused by breathing in spores of Aspergillus, a common mold. It cannot be spread between people or between people and animals. The CDC says cough and shortness of breath are common symptoms among all types of aspergillosis.

Aspergillosis isn't one disease. MedlinePlus describes several forms:

Allergic bronchopulmonary aspergillosis (ABPA)

ABPA is an allergic reaction to the fungus that usually develops in people who already have lung problems such as asthma or cystic fibrosis. Symptoms include cough, coughing up blood or brownish mucus plugs, fever, wheezing and weight loss. The CDC estimates ABPA likely affects between 1 and 15% of cystic fibrosis patients, and one study estimated 2.5% of adults who have asthma also have ABPA. Treatment uses immunosuppressive medicines such as prednisone, usually with antifungals; it usually improves over time, though relapse is common.

Aspergilloma (fungus ball)

An aspergilloma is a fungus ball that forms in lung areas with past disease or scarring, such as from tuberculosis or a lung abscess. It's usually not treated with antifungals unless it causes bleeding.

Chronic pulmonary aspergillosis

This long-term infection mostly follows other lung disease. The CDC cites estimates of about 1.2 million people with CPA after tuberculosis and over 70,000 as a complication of sarcoidosis.

Invasive aspergillosis

This is the serious form. The CDC says it occurs when the infection spreads from the lungs to other parts of the body, and that it is uncommon and occurs primarily in immunocompromised people. CDC clinical guidance lists those at risk as people with blood cancers, stem cell or solid organ transplants, prolonged very low white blood cell counts, or high-dose steroid or other immune-suppressing treatment. MedlinePlus says treatment involves several weeks of antifungal medicine.

The AAAAI position paper makes a useful point about home mold here: because Aspergillus is everywhere indoors and outdoors, host factors, rather than environmental exposure, are the main thing that decides who gets an opportunistic fungal infection. Your immune status matters more than whether you saw mold. That said, the CDC still says immune-compromised people should not stay in a moldy home, or even be there while it is being cleaned.

MedlinePlus defines hypersensitivity pneumonitis as inflammation of the lungs due to breathing in dust, fungus, molds, or other substances. It usually affects people who work where these are present at high levels. "Farmer's lung," from moldy hay, straw and grain, is a classic example. MedlinePlus also notes that humidifiers, heating systems, and air conditioners harboring fungi or bacteria can cause it. Keep those clean; see our guides to mold in AC vents and mold in a humidifier.

Table: hypersensitivity pneumonitis symptoms by stage.

Treatment starts with avoidance. MedlinePlus says the offending substance must be identified and avoided, and most symptoms go away when you avoid or limit your exposure. The outlook is good if exposure stops in the acute stage; in the chronic stage, the disease may keep progressing.

How likely is this from ordinary home mold? The CDC notes the Institute of Medicine found sufficient evidence linking indoor mold with hypersensitivity pneumonitis in individuals susceptible to that immune-mediated condition. The AAAAI paper adds that typical home exposure is an extremely unlikely cause of HP, except in highly unusual circumstances, such as workplace exposure. Uncommon, but real.

A doctor, not a mold test of your house, diagnoses lung disease. Depending on what they suspect, tests can include:

• For aspergillosis: MedlinePlus lists an Aspergillus antibody test, chest x-ray, complete blood count, CT scan, galactomannan blood test, IgE blood level, lung function tests, sputum culture and sometimes a biopsy.
• For hypersensitivity pneumonitis: MedlinePlus lists chest x-ray, CT scan, lung function tests, bronchoscopy with lavage, blood tests and sometimes a lung biopsy.
• For mold allergy that drives asthma: allergists use skin or blood tests.

These are ordered based on symptoms and history. The AAAAI paper says mold antibody (IgG) testing has demonstrated value for suspected HP or allergic lung disease, but only when the clinical picture fits. Using such tests as screening without that is discouraged. Online "mold toxicity" panels are a different thing; see our guide to mold exposure tests.

Call a doctor if you have a lasting cough, wheezing or shortness of breath, especially if symptoms ease when you're away from home or work. Tell them about any mold or water damage.

Get care right away:

• Weakened immune system with fever. MedlinePlus says to contact a provider right away if you have a weakened immune system and develop a fever, and right away if you develop symptoms of aspergillosis.
• Trouble breathing. Cleveland Clinic says to go to the nearest emergency room as soon as you can if you have trouble breathing.

For people with weak immune systems, the CDC suggests ways that may lower the chances of severe Aspergillus infection, such as avoiding dusty construction sites, wearing an N95 respirator if you can't, and avoiding close contact with soil or dust. The CDC notes these steps haven't been proven to prevent aspergillosis.

If you or a family member has asthma, lung disease or a weakened immune system, don't wait on household mold. The CDC says if you see or smell mold, you should remove it, and its cleanup guidance advises that people with immune suppression or underlying lung disease not take part in cleanup.

In Texas, TDLR allows unlicensed cleanup of less than 25 contiguous square feet of visible mold. For anything larger, hidden, or in a home with a high-risk person, hire a licensed mold testing company to assess it and a separate licensed mold removal company to remove it. Texas law says a license holder may not perform both mold assessment and mold remediation on the same project. After removal, clearance testing confirms the job is done.

Find licensed companies in Houston, Dallas, San Antonio or Fort Worth, or browse the Texas directory. Check licenses with our license check tool. For broader health context, see mold exposure and black mold symptoms.