Popcorn lung, or bronchiolitis obliterans, is a serious lung condition that damages the small airways in the lungs, causing coughing, shortness of breath, and difficulty breathing.

This condition was initially linked to inhaling diacetyl, a chemical used in microwave popcorn flavoring. Though some companies have stopped using it, diacetyl is still present in certain e-cigarette flavors.

Other chemicals that can cause popcorn lung include acetaldehyde (found in marijuana smoke and some e-cigarettes), formaldehyde, sulfur dioxide, and metal oxide fumes. It can also occur as a result of lung diseases like pneumonia or bronchitis, or even as a side effect of rheumatoid arthritis or lung transplant rejection.

Symptoms typically appear between 2 weeks and 2 months after exposure to harmful chemicals and may include a dry cough, shortness of breath, fatigue, and wheezing. Early detection is critical, as treatment can slow the progression of this irreversible condition. Avoiding harmful chemicals and seeking medical attention is essential.