Information on lung diseases that affect the air sacs known as alveoli. Includes pulmonary edema, ARDS, black lung, pneumonia, emphysema and more.

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Types and Causes of Lung Diseases - Diseases Affecting the Air Sacs (Alveoli)


(JANUARY 2014) A number of diseases adversely affect lung function. Some impact the airways or lung tissues directly while others impede normal breathing by transforming structures around the lungs. Together, they represent some of the most common health conditions in the United States. Causes range from genetics and infections to environmental influences and smoking.


After breath moves through the airways and into the lungs, it eventually branches off into tiny tubes called bronchioles that deliver air to small air sacs called alveoli, the walls of which are just one cell thick. These sacs make up the majority of surface area within the lungs, through which oxygen and carbon dioxide exchange occurs. Diseases that can affect air sacs include:


Emphysema is caused by the gradual loss of air sacs within the lungs. This loss results in less surface area for the absorption of oxygen, leaving the person constantly short of breath. As it progresses, breakdowns in the structure of the air sacs also makes it difficult to expel air as one breathes out. Smoking is the leading cause of this disease.


Pneumonia is an infection of the air sacs, usually caused by bacteria. Symptoms including coughing up mucus, chest pain and shortness of breath are common and may come on quickly. People are more likely to develop pneumonia while recovering from a cold or flu as the lungs’ ability to fight off infection is compromised. Similarly, people with asthma, cancer, heart disease or diabetes are more susceptible to pneumonia.

Tuberculosis (TB)            

Tuberculosis is an infection caused by the Mycobacterium tuberculosis bacteria. While it can infect any part of the body, it is most commonly found in the lungs. Once in the lungs, it produces symptoms similar to a slowly progressive pneumonia. It breaks down the connections between the air sacs, leading to emphysema. Tuberculosis is an infectious disease that can be transferred from one person to another.

Pulmonary Edema

Pulmonary edema is caused by excess fluid in the lungs. Fluid leaks out of small blood vessels in the lung and into the air sacs and surrounding area. This excess fluid makes it difficult to breathe. Heart problems are the most frequent cause of pulmonary edema, but it can also result from exposure to certain toxins, lung injury or high elevation.

Acute Respiratory Distress Syndrome (ARDS)

ARDS typically occurs in patients who are already critically ill or suffer serious injuries. Like pulmonary edema, excess fluids build up in the lungs, making it extremely difficult to breathe. Symptoms usually occur within a few days of the original illness or trauma. Life support with ventilation is usually necessary for the patient to survive while the lungs recover.

Pneumoconiosis (Black Lung Disease)

Black lung disease is also known as coal worker’s pneumoconiosis. The walls of the air sacs are inflamed by the inhalation of dust (likely coal dust). This creates scarring that stiffens the lungs and prevents proper inhaling and exhaling. Shortness of breath and chronic coughing are the most common symptoms.

People with lung disease or any serious ongoing medical condition should consider wearing a medical alert bracelet to provide critical information to first responders in case of emergency.



Types and Causes of Lung Diseases – Diseases Affecting the Airways

Types and Causes of Lung Diseases – Diseases Affecting the Other Tissues