The seven most common lung diseases are asthma, chronic obstructive pulmonary disease (COPD), lung cancer, pneumonia, pulmonary fibrosis, pulmonary hypertension, and lung infections like tuberculosis. Together, respiratory diseases rank as the fifth leading cause of death in the United States, responsible for roughly 145,643 deaths per year. Understanding what each condition does to the lungs, who it affects, and how it’s detected can help you recognize warning signs early.
Asthma
Asthma is a chronic condition in which the airways narrow and swell, making it harder to breathe. About 25 million Americans have it, roughly 7.7% of the population. It affects adults at a slightly higher rate (8%) than children (6.5%), though childhood asthma tends to get the most attention because it’s a leading cause of missed school days.
During an asthma attack, the muscles around your airways tighten while the lining produces excess mucus, leaving less room for air to pass through. Common triggers include allergens like dust mites and pollen, cold air, exercise, respiratory infections, and air pollution. Most people manage asthma with two types of inhalers: a quick-relief inhaler that relaxes airway muscles within minutes, and a daily controller inhaler that reduces the underlying inflammation over time. With consistent management, most people with asthma live without major limitations.
Chronic Obstructive Pulmonary Disease
COPD is an umbrella term covering two related conditions: emphysema, where the tiny air sacs in the lungs are destroyed, and chronic bronchitis, where the airways stay inflamed and produce excess mucus. Both make it progressively harder to exhale fully, trapping stale air in the lungs.
Smoking causes the vast majority of COPD cases, but long-term exposure to fine particulate matter, chemical fumes, and indoor air pollution also contributes. The World Health Organization has identified chronic exposure to fine particles as a direct risk factor for COPD because these particles are small enough to penetrate deep into lung tissue. Symptoms develop gradually, often starting as a persistent cough or mild shortness of breath that people dismiss as aging. By the time breathing becomes noticeably difficult, significant lung damage has already occurred.
A breathing test called spirometry is the standard way to diagnose COPD. It measures how much air you can force out in one second compared to the total amount you can exhale. A low ratio between these two numbers signals an obstructive pattern, meaning air is getting trapped. COPD can’t be reversed, but quitting smoking, pulmonary rehabilitation (structured exercise and breathing techniques), and inhaled medications can slow progression and improve quality of life considerably.
Lung Cancer
Lung cancer is the leading cause of cancer death in the United States for both men and women. It falls into two main categories: non-small cell lung cancer, which is far more common, and small cell lung cancer, which tends to grow and spread more aggressively.
Survival depends heavily on when the cancer is found. When lung cancer is caught while still confined to the lungs, the five-year survival rate is 65.5%. Once it spreads to nearby lymph nodes, that drops to 38.2%. If it has metastasized to distant organs, the rate falls to 10.5%. These numbers have improved in recent years thanks to better treatments and wider use of low-dose CT screening, which is now recommended for adults aged 50 to 80 who have a significant smoking history.
Smoking remains the dominant risk factor, but roughly 10 to 20% of lung cancers occur in people who have never smoked. Radon gas, which seeps into homes from the ground, is the second leading cause. Prolonged exposure to secondhand smoke, asbestos, and heavy air pollution also raises risk. Early lung cancer rarely causes symptoms, which is why screening matters so much. As tumors grow, persistent cough, chest pain, unexplained weight loss, and coughing up blood become more common.
Pneumonia
Pneumonia is an infection that fills the lungs’ air sacs with fluid or pus, making it difficult to get enough oxygen into the bloodstream. It killed over 41,600 Americans in 2024, a rate of about 12 deaths per 100,000 people. Bacteria, viruses, and fungi can all cause pneumonia, and the severity ranges from mild cases manageable at home to life-threatening infections requiring hospitalization.
The classic symptoms are a productive cough, fever, chills, and shortness of breath. For otherwise healthy adults, bacterial pneumonia typically responds well to antibiotics, with most people feeling significantly better within a few days and fully recovering within a few weeks. The danger increases sharply for adults over 65, young children, smokers, and anyone with a weakened immune system or existing lung disease. Vaccines against pneumococcal bacteria and influenza are the most effective preventive measures, since flu often opens the door to a secondary bacterial pneumonia.
Pulmonary Fibrosis
Pulmonary fibrosis occurs when lung tissue becomes scarred and stiff, making the lungs less elastic and less efficient at transferring oxygen into the blood. Unlike COPD, where exhaling is the main problem, pulmonary fibrosis makes it hard to take a full breath in. On spirometry, this shows up as a restrictive pattern: both the total volume and the one-second volume are reduced, but their ratio stays normal or even increases.
In many cases, the cause is never identified, a form called idiopathic pulmonary fibrosis. Known triggers include long-term exposure to asbestos, coal dust, silica, certain medications, and autoimmune diseases like rheumatoid arthritis. The scarring is irreversible, but medications can slow the rate at which it worsens. Symptoms typically begin with a dry cough and gradual breathlessness during activity, eventually progressing to difficulty breathing even at rest. Supplemental oxygen helps maintain activity levels as lung function declines, and lung transplantation is an option for eligible patients with advanced disease.
Pulmonary Hypertension
Pulmonary hypertension is high blood pressure in the arteries that carry blood from the heart to the lungs. It’s diagnosed when the mean pressure in the pulmonary artery exceeds 20 mm Hg, measured by threading a catheter into the right side of the heart. That threshold was revised downward in recent years to catch patients earlier in the disease process, before the heart sustains significant damage.
There are five broad categories based on the underlying cause: pulmonary arterial hypertension (a problem in the artery walls themselves), left heart disease, lung diseases or low oxygen levels, blood clots in the pulmonary arteries, and a group of mixed or unclear causes including sickle cell disease and sarcoidosis. The most common type by far is the one linked to left heart disease, where a failing left side of the heart causes pressure to back up into the lungs.
Early symptoms are easy to brush off: breathlessness during exercise, fatigue, and occasional dizziness. As the condition advances, the right side of the heart works harder and harder to push blood through narrowed lung arteries, eventually leading to right-sided heart failure. Swelling in the ankles and abdomen, chest pain, and fainting spells signal worsening disease. Treatment targets the underlying cause when possible, and for pulmonary arterial hypertension specifically, several classes of medication can relax and widen the lung’s blood vessels.
Tuberculosis
Tuberculosis (TB) is a bacterial lung infection that remains one of the top infectious disease killers worldwide, though it’s far less common in the United States than in many other countries. The bacterium spreads through airborne droplets when an infected person coughs or sneezes, making it particularly dangerous in crowded or poorly ventilated environments.
Most people who are exposed develop what’s called latent TB: the bacteria live in the body without causing symptoms, held in check by the immune system. About 5 to 10% of people with latent TB eventually develop active disease, with that risk rising significantly for people with weakened immune systems. Active TB causes a persistent cough lasting three weeks or more, chest pain, weight loss, night sweats, and sometimes coughing up blood. Treatment requires a long course of multiple antibiotics, typically lasting six to nine months. Stopping early, even when symptoms improve, can lead to drug-resistant TB strains that are much harder to treat.
How Air Quality Affects All of These
One thread runs through nearly every lung disease on this list: what you breathe matters. Fine particulate matter, particles small enough to bypass the body’s natural filters and settle deep into lung tissue, can enter the bloodstream and cause damage throughout the body. Short-term spikes in air pollution worsen asthma, trigger respiratory infections, and reduce lung function even in healthy people. Chronic exposure over years raises the risk of COPD, lung cancer, and cardiovascular disease.
Indoor air quality deserves equal attention. Radon, an odorless gas that accumulates in basements and ground floors, is a proven carcinogen. Secondhand smoke, cooking fumes in poorly ventilated kitchens, and mold exposure all stress the lungs over time. Testing your home for radon, improving ventilation, and avoiding prolonged exposure to smoke or chemical fumes are practical steps that lower risk across multiple conditions on this list.