The lungs are the major organs of the respiratory system, and are divided into sections, or lobes. The right lung has three lobes and is slightly larger than the left lung, which has two lobes.

The lungs are separated by the mediastinum. This area contains the heart, trachea, esophagus, and many lymph nodes. The lungs are covered by a protective membrane known as the pleura and are separated from the abdominal cavity by the muscular diaphragm.

With each inhalation, air is pulled through the windpipe (trachea) and the branching passageways of the lungs (the bronchi), filling thousands of tiny air sacs (alveoli) at the ends of the bronchi. These sacs, which resemble bunches of grapes, are surrounded by small blood vessels (capillaries). Oxygen passes through the thin membranes of the alveoli and into the bloodstream. The red blood cells pick up the oxygen and carry it to the body's organs and tissues. As the blood cells release the oxygen they pick up carbon dioxide, a waste product of metabolism. The carbon dioxide is then carried back to the lungs and released into the alveoli. With each exhalation, carbon dioxide is expelled from the bronchi out through the trachea.

Every organ in the human body serves an important purpose in keeping it running and in prime condition. Most healthy people are not cognizant of their organs—like lungs—on a daily basis, because they are able to breathe without difficulty and perform their daily tasks without major effort. But damage to these vital organs can cause serious disease, and sometimes death. Cigarettes can harm the tissue of the lungs, impeding their ability to function properly, and can increase the risk for conditions such as emphysema, lung cancer, and chronic obstructive pulmonary disease (COPD).

The primary function of your lungs is to deliver oxygen-rich blood to the rest of your body from the air you breathe in and expel carbon dioxide as waste when you exhale. While no tobacco product is safe, combustible products—or those you must light on fire to use, like cigarettes—are especially damaging to the lungs.

Smoking and Your Lungs

Cigarette smoking can cause immediate damage to your health. Each puff of cigarette smoke contains a mix of over 7,000 chemicals. When you breathe this in, the smoke hits your lungs very quickly, and the blood that is then carried to the rest of your body contains these toxic chemicals. Because tobacco smoke contains carbon monoxide, this deadly gas displaces the oxygen in your blood, depriving your organs of the oxygen they need.

Other chemicals found in cigarette smoke include acrolein, which can cause irreversible lung damage, and even in low amounts, it can cause a sore throat in 10 minutes. Cigarettes may also contain bronchodilators, or chemicals that are meant to open up the airways of the lungs and could increase the amount of dangerous chemicals absorbed by the lungs.

Cigarette smoking can have major consequences on the lungs at all ages. Babies whose mothers smoked during pregnancy may have lungs that develop abnormally, and teens who smoke cigarettes can develop smaller, weaker lungs that never grow to full size and never perform at their peak capacity. In addition, smoking can destroy the cilia—or tiny hairs in your airway that keep dirt and mucus out of your lungs. When these cilia are destroyed, you develop what is known as “smoker’s cough,” a chronic cough that is often seen in long-term or daily smokers.

Lung damage due to smoking does not end there. 8 out of 10 cases of chronic obstructive pulmonary disease (or COPD) are caused by smoking. People with COPD experience difficulty breathing and eventually die because of a lack of air. There is no cure for COPD. Furthermore, nearly all lung cancer—the top cause of cancer death in both men and women— is caused by smoking, and smokers are 20 times more likely to develop lung cancer than nonsmokers. In addition to lung cancer, smoking can lead to other respiratory cancers, such as:

• The oropharynx (the back of the mouth, including parts of the tongue, the soft palate, the side and back of the throat, and the tonsils)
• Larynx (the “voice box”)
• Trachea (the “windpipe”)
• Bronchus (one of two large airways that connect the trachea to the lungs)

Not Just Cigarettes: Other Tobacco Products and Lung Health

While cigarettes—given their high rate of use, addictive nature, and toxic mix of chemicals—are the most dangerous tobacco product, any tobacco product you inhale could cause lung damage. Cigar smoking can increase the risk of COPD, and lead to cancers of the lung, oral cavity, and larynx, among other cancers.

Electronic Nicotine Delivery Systems (ENDS), like e-cigarettes, are still relatively new tobacco products and are still being evaluated for their impacts on health. But e-cigarette use—or “vaping”—may be harmful to your lungs. Some e-cigarette aerosols have been found to contain some of the same chemicals in cigarettes, including the lung irritant acrolein, and formaldehyde, which may adversely affect the throat.Flavoring chemicals are considered safe for eating, but could be harmful when inhaled. Buttery flavors like caramel, toffee, and chocolate contain the chemicals diacetyl and acetoin, which can be harmful to your lungs. Additionally, fruit flavored e-cigarettes can have higher concentrations of a chemical called acrylonitrile, which is a known respiratory irritant.

How You Can Protect Your Lungs from Tobacco

Your lungs are one of your body’s filtration systems, taking in air from the atmosphere, adding oxygen to the blood for circulation throughout the body, and expelling excess carbon dioxide. When tobacco is inhaled, it interferes with this delicate balance. The best way to ensure lung health is to never start using tobacco, but if you are an addicted smoker, the sooner you quit, the sooner your lungs can begin to heal. Quitting smoking can lower the risk of getting cancer. In fact, when you quit smoking, your risk of:

• Cancer of the larynx is reduced immediately;
• Lung cancer drops by 50 percent 10 years after quitting;
• Mouth and throat cancers drop by 50% five years after quitting.

Anyone who quits smoking will experience better overall health. Just 12 hours after quitting, the carbon monoxide level in your blood drops to normal, allowing more oxygen to circulate to your organs.

Even though you can’t see it, the air you breathe can affect your health. Polluted air can cause difficulty breathing, flare-ups of allergy or asthma , and other lung problems. Long-term exposure to air pollution can raise the risk of other diseases, including heart disease and cancer.

Some people think of air pollution as something that’s found mainly outside. They may picture cars idling or power plants with smoke stacks. But air pollution can also occur inside—in homes, offices, or even schools.

Whether outdoors or indoors, the effects of air pollution are most obvious for those who already have difficulty breathing. “All people are likely susceptible to the adverse effects of air pollution. But people who have chronic lung diseases such as asthma are more susceptible,” explains Dr. Nadia Hansel, who studies lung problems at Johns Hopkins University.

NIH researchers are working to understand and reduce the impact that air pollution—both outdoors and indoors—has on health.

What’s Outside

Several different types of pollutants can affect your health. When the weather is warm, an invisible gas called ozone can make it harder for some people to breathe. This gas is created when sunlight triggers a chemical reaction between oxygen and certain pollutants from cars, factories, and other sources.

Ozone can irritate the lining of your airways and lungs. People with asthma and other lung conditions are more likely to feel its effects.

“When people with poorly controlled asthma are exposed to low levels of ozone, the amount of inflammation in the lungs goes way up,” explains Dr. Daryl Zeldin, a lung and environmental health science expert at NIH. “As a result, air passages narrow, which makes it much harder to breathe.”

Another type of outdoor pollutant that affects health is particulates. These are fine and coarse particles that are released when fuel is burned. They can come from things like cars, power plants, and wildfires. Research has linked particulates to short- and long-term lung problems.

To track these and other harmful pollutants, air quality monitors have been set up at over 1,000 locations across the country. The U.S. Environmental Protection Agency uses these monitors to produce the Air Quality Index (AQI). The index can be found online at www.airnow.gov.

People who are sensitive to outdoor pollution may want to use the AQI to track when levels are high. This information can help you make choices about when to do outdoor activities.

Improving Air Indoors

Indoor air pollution can be harmful, too. It can come from many sources. Secondhand tobacco smoke contains tiny particles that can hurt your lungs. Gas stoves and appliances can create harmful gases.

Pets and pests (such as mice and cockroaches) can shed substances, called allergens, that cause allergies. Mold and dust mites also produce allergens. Even furniture and cleaning products can release harmful compounds into the air.

In recent years, researchers have learned a lot about how exposure to indoor pollutants contribute to disease. “Studies are now asking: What do we do about it? What sorts of things can help reduce some of these exposures?” Zeldin says.

Several NIH-funded researchers are looking at ways to reduce harm from indoor air pollution. Hansel studies the use of air cleaners (also called air purifiers) to improve the air quality for older adults with chronic obstructive pulmonary disease (COPD). This condition makes it hard to breathe and puts people at increased risk of dangerous lung infections, such as pneumonia.

“Studies have shown that high pollutant levels inside the home can make breathing harder for people with COPD,” Hansel says.

Hansel’s team is now testing whether using air cleaners with special filters in the home can decrease COPD symptoms. The filters they’re testing remove both particulates and nitrogen dioxide, a gas pollutant produced by cooking.

The researchers will compare COPD symptoms in people who use the filters with those who don’t. They hope the use of the filters will also reduce hospital visits.

Research has shown that improving indoor air quality in the home can improve the health of kids with lung conditions, explains Dr. Wanda Phipatanakul, a children’s health expert at Boston Children’s Hospital.

But while air quality in the home matters, children can spend more than eight hours a day indoors at school. Improving air quality in schools has the potential to improve the health of many children at once, Phipatanakul adds.

“Home-based interventions help individual families, but targeting schools could help all the kids that are there, and has much more potential for impact,” she says.

Phipatanakul is running an NIH-funded study in about 40 schools. The intervention includes air cleaners in classrooms to remove particles and special pest control strategies to reduce allergens. The researchers are tracking children with asthma at the schools over the school year to see if the intervention improves their symptoms.

Research has shown that, in addition to improving health, improving indoor air quality can also boost how well kids do in school. “Kids who come to school and aren’t as sick are going to do better. So that’s kind of the overall goal,” Phipatanakul says.

Inside Out

One good thing about indoor air pollution is that many causes can be removed or changed. “It’s difficult to change the outdoor environment,” Phipatanakul says, “but indoors is more contained.”

A simple tool for many homes is making sure inside air has a chance to escape. “Ventilating your house, such as opening windows, can actually lower the air pollution levels inside, and it really doesn’t cost anything,” Hansel explains.

This strategy may not work on days when outdoor pollution is very high, she says. Paying attention to the AQI or other measures of outdoor air quality can help you decide when to let inside air out.

Tips to Breathe Easier

To reduce the effects of poor quality air on your health:

• Avoid outdoor activities in the afternoons on warm days, when the risk of air pollution is highest.
• Avoid strenuous outdoor activities if the air is polluted.Check your region’s air quality index (EPA). Orange and red mean it’s a bad air day, so people with lung problems should avoid the outdoors. Purple and maroon mean air pollution is extreme, and everyone should try to stay in an indoor environment with clean air.
• Reduce pollutants in your home. Don’t let anyone smoke in your home. Avoid burning candles, incense, or wood fires. Run fans or open a window when cooking. Use a vacuum with a HEPA filter instead of sweeping to avoid stirring up dust and allergens.

It is normal for lung function to decline gradually after age 35. For example, lung tissue may lose some elasticity, causing airways to get a little smaller. But it is still important to pay attention to changes in your breathing, such as a nagging cough and other signs.

Knowing the early warning signs of lung disease may help you receive treatment before the disease becomes more serious. Contact your provider if you have any of the following warning signs:

• Chronic cough – Lasts two months or longer

• Shortness of breath – Difficulty breathing that does not go away after exercising, or occurs with little or no effort

• Chronic mucus production – Lasts one month or longer

• Wheezing – Breathing that makes a noise

• Coughing up blood – Even small amounts may signal the presence of a lung infection

• Chronic chest pain – Lasts one month or longer, especially if it gets worse when you breathe in or when you cough

Based on your symptoms and medical exam, your provider may recommend lung tests to measure your lung function, lung volume, and blood gases to help diagnose the problem.

Some lung diseases affect the airways or tubes that carry oxygen and other gases into and out of the lungs. This often causes a narrowing or blockage, making it feel like breathing through a straw. Examples include asthma and chronic obstructive pulmonary disease (COPD). Another type affects the lung tissue, such as pulmonary fibrosis. Scarring or inflammation prevents the lungs from expanding fully, which can feel like wearing a too-tight vest.

Other lung diseases damage blood vessels in the lungs. One example is pulmonary hypertension, which is high blood pressure in the blood vessels leading from the heart to the lungs. This can cause shortness of breath, especially when a person exerts themselves.

Some of the most common lung diseases include the following:

• COPD – This occurs when airways in the lungs become inflamed and thicken. Less oxygen gets into the body’s tissues, making it harder to get rid of carbon dioxide. COPD includes emphysema and chronic bronchitis. Symptoms include chronic cough and shortness of breath. The main cause of COPD is smoking, but nonsmokers can get COPD, too. Other risk factors include air pollution and working with chemicals, dust, and fumes. There is no cure, but COPD can be managed with medicines and breathing therapies.

• Pneumonia – This lung infection is caused by bacteria, viruses, or fungi. Symptoms vary from mild to severe. These include a cough, which may include greenish or bloody mucus, fever, and shortness of breath. Most healthy people recover in one to three weeks with treatment, but pneumonia can be life threatening, too.

• Lung Cancer – Cancer forms in the tissues of the lung. Smoking is the leading cause of lung cancer. Other causes include secondhand smoke, family history, air pollution, and exposure to certain chemicals, radiation, and radon gas. Early lung cancer may not cause symptoms. Treatment may include surgery, chemotherapy, and radiation therapy, depending on the type and how advanced it is. If lung cancer is found at an earlier stage, it is more likely to be treated successfully.

Breathing is something your body does naturally every day to survive. But did you know that breathing is also a tool you can use to help relieve stress and stay calm?

By making a few simple tweaks to change your breathing, you can release more “feel-good” hormones and slow down your heart rate. You can also supply more oxygen to your blood. This makes every system in your body work better. Breathing for stress relief is about slowing down your breathing, taking deeper breaths, and controlling your exhales.

There are many simple breathing techniques you can use at any time. These may be helpful when you feel stressed out talking to someone, stuck in traffic, or any time you would like to take a few minutes to relax. Breathing exercises can also be a part of your “wind down” activities before bedtime to help prepare your body and mind for sleep.

Here are two simple breathing techniques that take just a few minutes to do:

• Square Breathing. Breathing is typically done in two parts: 1. breathe in and 2. breathe out. Square breathing adds two more parts, as in four sides to a square: 1. breathe in, 2. hold your breath, 3. breathe out, and 4. hold your breath. You can do this to any count that is comfortable for you. For example, breathe in for two counts, hold for two counts, breathe out for two counts, and hold for two counts. Repeat this breathing cycle for a few more minutes.

• Ocean Breathing. This technique is like breathing with the waves. Picture yourself standing on a beach by the ocean. Imagine that you have your bare feet in the sand while you watch the waves. Next, match your breathing to the rhythm of the waves – breathe in as the waves come in and breathe out as the waves go out. Repeat this breathing cycle for a few more minutes.

These breathing techniques can help you slow down and be more present in your day. You can use them any time and any place to help take care of yourself. If you feel like you need more help with stress relief, talk with your provider.

Your lungs are amazing, allowing you to breathe about 20,000 times a day, around the clock.

When you breathe in, air travels down into the alveoli (air sacs) in your lungs. This is where oxygen from the air moves to your blood and travels to all parts of your body. As this happens, carbon dioxide moves from your blood to your lungs. When you breathe out, the carbon dioxide leaves your body.

Protecting Lung Health

Your body has natural defenses to protect your lungs from germs and other harmful substances. In addition, here are things you can do to keep your lungs healthy for life and reduce your risk of lung disease:

• Quit smoking or don’t smoke. If you smoke, it’s never too late for your lungs to benefit from quitting. When you are ready, ask your health provider about resources available to help you quit. Avoid secondhand smoke. Make your home and car smoke-free.

• Avoid exposure to pollutants. Test your home for radon gas and ensure it is well ventilated. Use protective gear if you work around dust, chemicals, fumes, or other pollutants. Avoid outdoor exercise on bad air days.

• Protect yourself from infections. Get a flu shot every year. Ask about a vaccine to protect against pneumonia if you are 65 or older. If you haven’t already, get a COVID-19 vaccine. This is your best protection against severe lung related illness if you are infected with COVID-19.

• Aim for a healthy weight. Lose excess weight to maintain proper lung function and reduce risk for airway diseases.

• Exercise. Be physically active to strengthen your lungs and heart so they work most efficiently.

• Get regular checkups. See your provider for regular checkups. Getting recommended health screenings help prevent lung diseases. In fact, early detection could save your life.