When you inhale (breathe in), air enters your lungs and oxygen from the air moves from your lungs to your blood. At the same time, carbon dioxide, a waste gas, moves from your blood to the lungs and is exhaled (breathe out). This process is called gas exchange and is essential to life.

In addition to the lungs, your respiratory system includes the trachea (windpipe), muscles of the chest wall and diaphragm, blood vessels, and tissues that make breathing and gas exchange possible. Your brain controls your breathing rate (how fast or slow you breathe), by sensing your body’s need for oxygen and its need to get rid of carbon dioxide.

Healthy lifestyle habits, such as physical activity and not smoking, can help prevent lung injury and disease.

Chronic obstructive pulmonary disease (COPD). This includes:

Lung cancer. This is an abnormal growth of cells that can result in lumps, masses, or tumors. It may start in the lining of the bronchi, or other areas of the respiratory system. Smoking, including secondhand smoke, is the leading cause of lung cancer. Symptoms of lung cancer include:

Panagis Galiatsatos, M.D., M.H.S., is an expert on lung disease at Johns Hopkins Bayview Medical Center and sees patients with COVID-19. He explains some of the short- and long-term lung problems brought on by the new coronavirus.

Cigarette smoking is the major cause of lung cancer and chronic obstructive pulmonary disease (COPD), which includes chronic bronchitis and emphysema. Cigarette smoke can narrow the air passages and make breathing more difficult. It causes chronic inflammation, or swelling in the lung, which can lead to chronic bronchitis. Over time cigarette smoke destroys lung tissue and may trigger changes that grow into cancer. If you smoke, it's never too late to benefit from quitting. The American Lung Association can help whenever you are ready.

Secondhand smoke, chemicals in the home and workplace, and radon all can cause or worsen lung disease. Make your home and car smokefree. Test your home for radon. Avoid exercising outdoors on bad air days. And talk to your healthcare provider if you are worried that something in your home, school or work may be making you sick.

The air quality outside can vary from day to day and sometimes is unhealthy to breathe. Knowing how outdoor air pollution affects your health and useful strategies to minimize prolonged exposure can help keep you and your family well. Climate change and natural disasters can also directly impact lung health.

A cold or other respiratory infection can sometimes become very serious. There are several things you can do to protect yourself:

Regular check-ups help prevent diseases, even when you are feeling well. This is especially true for lung disease, which sometimes goes undetected until it is serious. During a check-up, your healthcare provider will listen to your breathing and listen to your concerns. If you need health insurance, learn more about your options.

Whether you are young or old, slender or large, able-bodied or living with a chronic illness or disability, being physically active can help keep your lungs healthy. Learn more about how exercise can strengthen your lungs.