What happens to your lungs from smoking? 3 things to know

Roughly 85% of all lung cancer diagnoses are caused by smoking. But what does smoking actually do to your lungs? 

Does the lung damage start from your very first puff or vape, or only after years of a pack-a-day habit? How long does it take your body to recover once you stop smoking? And is the lung damage caused by smoking temporary or permanent? 

We asked tobacco treatment expert and addiction specialist Maher Karam-Hage, M.D. Here are three things that he wants you to know. 

Nicotine isn’t what causes lung damage. Tar is.

There’s no question that nicotine is an addictive substance. And using products that contain this chemical before age 25 can permanently alter parts of the brain that control attention, learning, mood and impulse control. Nicotine obtained through smoking is even more addictive. 

Still, when it comes to lung damage, Karam-Hage stresses, “While nicotine has many effects on the body, it’s not what’s causing illnesses or damaging your lungs. The damage is actually done by tar – the black, sticky substance created when some of the chemicals in cigarettes burn and melt together.” 

Experts estimate that cigarette smoke contains between 7,000 and 8,000 different chemicals. About 70 of those are known carcinogens, or substances that can cause cancer. So, whenever you inhale cigarette smoke, you’re bathing the delicate lining of your lungs in a toxic fog. This can leave a thin coating of tar on its surface similar in color and composition to the kind used to pave streets. And every time you smoke, you’re adding more damage. 

Smoking causes damage to lungs over time — and it’s permanent

Your lungs contain around 500 million tiny air sacs called alveoli that pull oxygen from the air you breathe and release carbon dioxide when you exhale. Smoking destroys these air sacs by killing the cells that line them. 

“Many structures in the body are capable of repairing themselves,” says Karam-Hage. “If you break a bone, for instance, it will eventually mend. If you cut your skin, it will heal. Even the liver can grow back sometimes if a portion of it is removed. But lung tissue doesn’t grow back. Once it’s gone, it’s gone.” 

Damage to alveoli gets worse over time, too. And as lung tissue is damaged, it becomes more fibrous, making it harder for people to expand their lungs fully with each inhalation. Less lung tissue and less expansion mean less oxygen getting to all the places it’s needed. That’s why many people don’t think there’s a problem until they start feeling short of breath. 

“It happens silently. So, smokers just keep walking around because they don’t feel anything,” says Karam-Hage. “And since people start out with millions of alveoli, it can take 15 or 20 years to lose enough of them to really become obvious. But once you develop something like chronic obstructive pulmonary disease (COPD), there’s no going back. Once you get to that point, you’re never going to get off the oxygen tank.”  

Still, Karam-Hage notes, “It really is kind of amazing that some smokers don’t develop lung cancer. Their lungs are getting so much daily exposure to smoke and carcinogens.”

Quitting smoking offers lung and heart health benefits

Thinking about the effects of smoking on lung tissue can be scary. But the good news is, quitting at any age can still benefit your health. 

“Statistically, smoking shortens your life span by 10 to 15 years,” says Karam-Hage. “But if you quit by age 30, you can recover almost all of them. One year after quitting smoking, your risk of having a heart attack goes down by half, too. And four years later, your risk reverts to the same as a non-smoker’s. Five years after quitting, your risk of developing cancer due to smoking falls by 50%, and after 15 years, it reverts to the same as someone who has never smoked.” 

Don’t be deterred, though, if you hear about people who had heart attacks or developed cancer even after quitting cigarettes. 

“Sometimes, I have patients tell me, ‘See? I quit smoking and then I still had a heart attack a year later. So, smoking didn’t have anything to do with it,’” says Karam-Hage. “What they don’t understand is that they didn’t have the heart attack because they quit smoking. They had it because of the 10 years they smoked before that. So, quit as soon as you can to give your body as much time as possible to recover.” 

Learn about smoking cessation studies at MD Anderson.