Learn About Respiratory Disease Information Guide

Understanding Respiratory Diseases: What They Are and How They Develop

Respiratory diseases are conditions that affect how your lungs and airways work. These diseases damage your ability to breathe properly, which means your body may not get enough oxygen. According to the World Health Organization, respiratory diseases cause about 4 million deaths each year worldwide, making them one of the leading causes of death globally.

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Your respiratory system includes your nose, mouth, windpipe (trachea), lungs, and the small air sacs inside your lungs called alveoli. When you breathe in, air travels through your airways into these tiny air sacs, where oxygen enters your blood. Carbon dioxide—a waste product your body creates—leaves your blood and gets expelled when you exhale. When disease damages any part of this system, the process breaks down.

Respiratory diseases fall into two main categories: obstructive and restrictive. Obstructive diseases make it hard to move air out of your lungs because the airways become narrowed or blocked. Restrictive diseases reduce how much air your lungs can hold because lung tissue becomes stiff or scarred. Some diseases have characteristics of both types.

Several factors increase your risk of developing respiratory disease. Smoking is the leading cause—it damages lung tissue directly and increases risk for conditions like chronic obstructive pulmonary disease (COPD) and lung cancer. Other risk factors include long-term exposure to air pollution, chemical fumes in the workplace, family history of lung disease, repeated childhood respiratory infections, and certain genetic conditions. Age also plays a role, as some respiratory diseases become more common as people get older.

Practical takeaway: Understanding how your respiratory system works and what damages it helps you recognize symptoms early. Keep track of any persistent cough, shortness of breath, or chest pain that lasts more than a few weeks, and discuss these symptoms with your doctor.

Common Respiratory Diseases: Recognizing Symptoms and Types

Chronic obstructive pulmonary disease (COPD) is one of the most common respiratory diseases. COPD includes emphysema and chronic bronchitis, conditions that make breathing progressively more difficult. The American Lung Association reports that about 16 million Americans are living with COPD, though many more may have it without knowing. COPD typically develops after years of smoking or exposure to air pollutants. Symptoms include persistent cough (sometimes called "smoker's cough"), shortness of breath during normal activities, wheezing, and chest tightness.

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Asthma is another widespread respiratory condition affecting about 25 million Americans. Unlike COPD, asthma can develop at any age and often begins in childhood. Asthma causes inflammation and narrowing of the airways, leading to sudden episodes called asthma attacks. During an attack, people experience severe shortness of breath, wheezing, coughing (especially at night or during exercise), and chest pain. Some people have mild asthma with few symptoms, while others have severe asthma that significantly limits their activities.

Pneumonia is an acute infection that inflames the air sacs in your lungs, which fill with fluid or pus. Pneumonia can be caused by bacteria, viruses, or fungi. The Centers for Disease Control and Prevention reports that pneumonia causes over 50,000 deaths annually in the United States. Symptoms include cough (sometimes with phlegm), fever, chills, fatigue, shortness of breath, and chest pain when breathing or coughing. While some people recover quickly with treatment, others—especially older adults and people with weak immune systems—face serious complications.

Other common respiratory diseases include pulmonary fibrosis (scarring of lung tissue that makes breathing progressively harder), bronchiectasis (permanent damage to airways), interstitial lung disease (inflammation and scarring of the tissue between air sacs), and sleep apnea (repeated breathing pauses during sleep). Lung cancer develops when abnormal cells grow in the lungs and can spread to other parts of the body. Tuberculosis, caused by bacterial infection, is less common in developed countries but remains a serious global health threat.

Practical takeaway: Different respiratory diseases have different symptoms and require different treatments. Write down any symptoms you experience over two weeks—when they occur, what makes them worse or better, and how they affect your daily life. This information helps your doctor identify what might be causing problems.

How Respiratory Diseases Are Diagnosed: Tests and Evaluations

Your doctor will start by asking questions about your medical history, current symptoms, and whether you smoke or have been exposed to harmful substances. They'll ask when your symptoms started, whether you cough up anything, whether you feel short of breath during rest or activity, and whether anyone in your family has had respiratory disease. This conversation gives your doctor important clues about what might be happening.

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A physical examination comes next. Your doctor listens to your lungs using a stethoscope, checking for abnormal sounds like wheezing or crackles. They check your oxygen level using a pulse oximeter—a small device that clips onto your finger and measures the percentage of oxygen in your blood. Normal oxygen levels are usually 95% or higher. They may also check how fast you're breathing and look for other signs like swollen ankles or lips with a bluish tint, which can indicate your lungs aren't delivering enough oxygen to your body.

Spirometry is the most common lung function test. You breathe into a machine called a spirometer that measures how much air your lungs hold and how fast you can breathe air out. This test helps doctors detect obstructive diseases like asthma and COPD. A chest X-ray creates a picture of your lungs and can reveal pneumonia, pulmonary fibrosis, lung cancer, or other abnormalities. CT scans provide more detailed images than X-rays and help doctors detect smaller problems and determine how far diseases have progressed.

Depending on your symptoms and initial test results, doctors may perform additional tests. Arterial blood gas tests measure oxygen, carbon dioxide, and acid levels in your blood. Bronchoscopy involves threading a thin tube with a camera down your windpipe to examine airways directly and collect tissue samples if needed. Sleep studies monitor your breathing, oxygen levels, and heart rhythm while you sleep to diagnose sleep apnea. Sputum tests examine phlegm you cough up to identify bacterial or fungal infections. The specific tests your doctor orders depend on what respiratory disease they suspect based on your symptoms and initial evaluation.

Practical takeaway: These tests are not invasive or painful, though some people find them uncomfortable. Understanding what each test measures helps you prepare and communicate with your doctor about any concerns. Ask your doctor which tests they recommend and why, so you understand what information each one provides.

Risk Factors and Prevention: Reducing Your Respiratory Disease Risk

Smoking is responsible for about 80% of COPD cases and significantly increases risk for asthma attacks, lung cancer, and other respiratory diseases. If you currently smoke, quitting is the single most important action you can take to protect your lungs. The good news is that lung function can improve after quitting—even for people who have smoked for decades. Within one week of quitting, cilia (tiny hair-like structures that clean your airways) begin healing and moving mucus more effectively. Within three months, lung function can improve by up to 30%.

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Air quality affects everyone's respiratory health. Long-term exposure to outdoor air pollution containing particulate matter, ozone, nitrogen dioxide, and sulfur dioxide damages lung tissue and increases respiratory disease risk. If you live in an area with poor air quality, limit outdoor activity on high-pollution days—check your local air quality index. Secondhand smoke is also dangerous, containing more than 7,000 chemicals, hundreds of which are poisonous and about 70 can cause cancer. Children exposed to secondhand smoke have higher rates of asthma, pneumonia, and ear infections.

Workplace exposures cause about 15% of COPD cases. People who work with asbestos, silica dust, coal dust, grain dust, metal fumes, or chemical vapors face elevated respiratory disease risk. If your job involves these exposures, use protective equipment provided by your employer, follow safety procedures, and report unsafe conditions. Many respiratory diseases from occupational exposure develop gradually after years of exposure, so protecting yourself now prevents problems decades later.

Other modifiable risk factors include maintaining a healthy weight, exercising regularly, eating a diet rich in vegetables and fruits (which contain antioxidants that protect