How Smoking Affects the Lungs

Burning tobacco produces more than 4,000 chemicals, including nicotine, carbon monoxide, and tars. These chemicals can transform normal cells into cancer cells.

Find out how:

  • Smoking changes your lungs and airways.
  • Quitting smoking can help reduce your risk of many health problems — from a troublesome cough to life-threatening conditions, like COPD and cancer.
  • Secondhand smoke has a harmful effect on your lungs.

The Effects of Cigarettes to Your Lungs and Airways

Smoking causes significant changes in your lungs and airways. Some changes are sudden, lasting just a short time, such as colds and pneumonia. Other more chronic changes happen slowly and can last a lifetime — like emphysema.

Here are some of the changes that happen in your lungs and airways when you smoke.

More mucus and infections

When you smoke, the cells that produce mucus in your lungs and airways grow in size and number. As a result, the amount of mucus increases and thickens.

Your lungs cannot effectively clean out this excess mucus. So, the mucus stays in your airways, clogs them, and makes you cough. This extra mucus is also prone to infection.

Smoking causes your lungs to age faster and hinders their natural defense mechanisms from protecting you against infection.

Less airflow

Smoking inflames and irritates the lungs. Even one or two cigarettes cause irritation and coughing.

Smoking also can destroy your lungs and lung tissue. This decreases the number of air spaces and blood vessels in the lungs, resulting in less oxygen to critical parts of your body.

Fewer cilia

The lungs are lined in broom-like hairs called cilia, which clean the lungs.

A few seconds after you light a cigarette, cilia slow down in movement. Smoking just one cigarette can slow the action of your cilia for several hours. Smoking also reduces the number of cilia in your lungs, leaving fewer to properly clean them. 

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Additional Health Risks Caused by Smoking


Cigarette smoking can be very damaging to your circulation system. Because the tar in cigarettes contains harmful chemicals, your blood stream is infected by them when you smoke. When these poisons enter your blood:

  • You are at an increased risk for experiencing blood clots, as your blood becomes thicker.
  • Your blood pressure and heart rate increase, causing your heart to work harder.
  • Your arteries become thinner, which reduces the amount of blood carrying oxygen as it circulates to your organs.


Smoking cigarettes is also quite harmful to your brain. Smokers are 50% more likely to have a stroke compared with nonsmokers. With that, smokers are twice as likely to die from a stroke.


Your digestive system, particularly your stomach, is greatly impacted by smoking cigarettes. The esophagus can be weakened by smoking, allowing acid to travel in the wrong direction through it. This process is better known as reflux.


Though few people are aware, smoking reduces the amount of oxygen your skin receives. In other words, smoking causes your skin to age faster, by 10 to 20 years. Facial wrinkling is likely to occur around your eyes and mouth.

How Quitting Smoking Can Benefit Your Health

When you smoke, you have a much greater chance of developing health problems.

Breathing-related health problems from smoking

When you smoke: When you quit:
  • Chronic cough.
  • More mucus.
  • Shortness of breath.
  • Wheezing.
  • Fast decrease in breathing-related symptoms, no matter how much or how long you smoked.
  • Easier breathing within 72 hours.
  • Marked decrease in cough, mucus, shortness of breath, and wheezing within one month.
  • Less irritated and inflamed airways.
  • Cilia growth in one to nine months.
  • Lungs more able to handle mucus, self-clean, and fight infection.


Asthma is a chronic airway disease. People with asthma have periods of shortness of breath, wheezing, chest tightness, and cough.

When you smoke: When you quit:
  • Asthma symptoms are harder to control.
  • Many inhalers aren’t as effective.
  • Symptoms of asthma decrease.

Colds and lung infections

When you smoke: When you quit:
  • More colds and lung infections.
  • Worse colds and lung infections.
  • Fewer colds and lung infections.
  • Milder colds and lung infections.

Flu and pneumonia

Smoking increases the number of deaths from flu and pneumonia. As fewer people smoke, the death rate from flu and pneumonia also has declined.

When you smoke: When you quit:
  • More and worsened bouts of the flu.
  • More chance of pneumonia.
  • Poor response to flu vaccine.
  • 50% less risk of pneumonia within five years.
  • Fewer and milder bouts of the flu.
  • Better response to flu vaccine.

Chronic obstructive pulmonary disease (COPD)

Cigarette smoking is a major cause of chronic obstructive pulmonary disease, or COPD. COPD blocks the flow of air into and out of your lungs. It’s a leading cause of death in the United States.

When you smoke, your risk of death from COPD is 10 times greater than if you did not smoke.

COPD includes two diseases: chronic bronchitis and emphysema.

When you have chronic bronchitis: When you quit smoking:
  • You develop a long-lasting cough every year.
  • Your cough produces excess mucus that blocks airflow.
  • Chronic bronchitis symptoms decrease.
  • Symptoms of chronic bronchitis may disappear over time.
When you have emphysema: When you quit smoking:
  • It destroys your lung tissue over time.
  • Your lungs are less able to take in fresh air and let out stale air.
  • Your lungs and airways produce excess mucus that blocks airflow.
  • You get a small improvement from emphysema symptoms right away.
  • The disease slows down.
  • You have a better chance of living longer.

Lung cancer

Lung cancer is the leading cause of cancer death in the United States. Smoking causes 85% of lung cancer cases.

Smokers have a higher number of precancer changes in their airways than nonsmokers.

When you smoke: When you quit:
  • Precancerous tissue can change to cancer.
  • Your risk of lung cancer and death are 20 times greater than that of a nonsmoker.
  • This risk increases the more you smoke and the longer you smoke.
  • Precancerous tissue may return to normal.
  • Your risk of lung cancer decreases within five years.
  • Your risk of lung cancer keeps decreasing over time.

How Secondhand Smoke Affects Your Lungs

When people smoke, they pollute the air around them. This secondhand smoke comes from two sources:

  1. The burning end of the cigarette.
  2. The smoker when they exhale smoke.

Researchers have studied adult nonsmokers who breathe cigarette smoke in the workplace, and results show these adults have impaired lungs.

When you breathe second-hand smoke, you can have health problems, such as:

  • Wheezing.
  • Chronic cough.
  • Increased mucus.
  • Shortness of breath.
  • Trouble controlling asthma.
  • More lung infections and pneumonia.
  • Lung cancer.

In the United States each year, about 3,000 people die from lung cancer caused by secondhand smoke.

Stay away from secondhand smoke.

Get Help to Quit Smoking

UPMC offers smoking cessation programs to help people quit smoking. To get help or learn more about our programs to quit smoking, call the UPMC Referral Service at 1-800-533-UPMC (8762).

Editor's Note: This article was originally published on , and was last reviewed on .

About UPMC

Headquartered in Pittsburgh, UPMC is a world-renowned health care provider and insurer. We operate 40 hospitals and 800 doctors’ offices and outpatient centers, with locations throughout Pennsylvania, Maryland, New York, West Virginia, and internationally. We employ 4,900 physicians, and we are leaders in clinical care, groundbreaking research, and treatment breakthroughs. U.S. News & World Report consistently ranks UPMC Presbyterian Shadyside as one of the nation’s best hospitals in many specialties and ranks UPMC Children’s Hospital of Pittsburgh on its Honor Roll of America’s Best Children’s Hospitals. We are dedicated to providing Life Changing Medicine to our communities.