As a thoracic surgeon, I spend a lot of time talking to patients about the impact of smoking on their risk of lung cancer, breathing capacity, and overall health. But what often surprises people is how quickly their body, especially the lungs, begins to heal once they quit smoking. The lungs are remarkably resilient, and the improvements after stopping can make a big difference in how you feel and breathe.  

Whether you’ve been smoking for a few years or several decades, it’s never too late to quit, and your lungs will start to recover almost immediately. Here’s what happens to your lungs in the weeks, months, and years after quitting—and how a low-dose CT scan can help save lives. 

What happens 3 weeks after quitting smoking? 

Even at this early stage, your lungs and body begin to experience positive changes: 

  • Improved Circulation: Blood vessels narrowed by smoking begin to open up, improving blood flow and oxygen delivery to your lungs and other organs. 
  • Healing Cilia: Tiny hair-like structures in your lungs (cilia) begin to recover, helping your body clear out mucus, bacteria, and other harmful substances. 
  • Easier Breathing: As your lungs clear out built-up mucus, you’ll notice it’s easier to breathe deeply, and coughing becomes less frequent. 

What happens 3 Months after quitting smoking? 

By the three-month mark, the improvements become more noticeable, especially if you’re active: 

  • Lung Capacity Boost: Lung function can increase by up to 30%, making it easier to exercise, walk, or climb stairs without getting out of breath. 
  • Decreased Lung Infections: With cilia now functioning properly, your lungs are better at clearing germs, lowering your risk of infections like bronchitis and pneumonia. 
  • Less Mucus Production: The excessive mucus production triggered by smoking decreases, resulting in clearer airways and fewer coughing fits. 

What happens 3 years after quitting smoking? 

By the time you’ve reached the three-year mark, the long-term benefits become clearer: 

  • Reduced Risk of Lung Diseases: Your risk of chronic lung conditions like chronic obstructive pulmonary disease (COPD) is significantly lower. Quitting smoking prevents the progression of COPD, preserving lung function. 
  • Lowered Lung Cancer Risk: Although your risk isn’t completely erased, quitting smoking drastically reduces the chances of developing lung cancer.  
  • Better Physical Stamina: Your lung function continues improving, making engaging in physical activities easier without feeling winded. 

How low-dose CT screening saves lives 

One important step to take after you stop smoking is getting a low-dose CT (LDCT) lung cancer screening. Low-dose lung screening CT scans for smokers who have smoked one pack a day for 20 years and are between the ages of 55 and 80 have been shown to identify early lung cancer. This allows the patient to be treated with a much higher long-term survival rate and may reduce overall lung cancer deaths by 20%. LDCT is a powerful tool to detect lung cancer early—before symptoms appear. Elliot Hospital offers minimally invasive robotic diagnostic biopsy and surgery to treat lung cancer with minimal pain and enhanced recovery. 

The bottom line: quit smoking and get screened 

Quitting smoking is the best thing you can do for your lungs and your overall health. Your lungs begin to heal in just a few weeks, and the improvements are life-changing in three years. Combine that with low-dose CT screening, giving yourself the best chance at a long, healthy life. For more information and tips on how to stop smoking, visit the CDC’s Quit Smoking website. 

Dr. Curtis Quinn performed his undergraduate medical school general surgical training and cardiothoracic surgical training at Tufts University in Medford, MA, and Tufts Medical Center in Boston. He is board-certified in surgery and thoracic surgery and practices at Elliot Thoracic Surgery in Manchester, New Hampshire.