Bronchitis is an inflammation or swelling of the bronchi, accompanied with daily cough and the production of mucus. Mucus could lead to narrowing and obstruction of the airways, which increases the likelihood of bacterial lung infections. When fetid sputum is brought up, it gives the breath an unwholesome odor.
Pneumonia is a lung infection where the alveoli (the mini sacs that absorb the oxygen) become inflamed and flooded with fluid. That can be caused by different types of germs, including bacteria, viruses, fungi, and parasites. It may lead to a foul smell arising from the lungs.
Emphysema is caused by loss of elasticity in the lung tissue. The lungs loose their shape. The small airways collapse during exhalation, leading to an obstruction. Normal airflow is impeded, which primarily causes shortness of breath. The destruction of lung tissue around smaller airways, may cause unpleasant odors exhaled in breathing.
Lung Abscess is a cavity filled with pus (necrotic debris or fluid) caused by microbial infection in the lung, surrounded by inflamed tissue. It can produce very foul-smelling breath.
Tuberculosis (TB) is a bacterial infection caused by a germ called Mycobacterium tuberculosis. The bacteria usually attack the lungs, but they can also damage other parts of the body. It have been reported to cause foul odor in expired air.