Quitting smoking is one of the best decisions a person can make for their health. Within weeks, breathing may become easier, coughing may reduce, and the risk of heart disease starts to lower. However, a new study suggests that even after someone stops smoking, their lungs may continue to have lasting damage. Researchers found that while some lung cells can recover after quitting, others continue to show changes that may increase the risk of chronic lung disease years later.

The findings do not mean that quitting smoking is ineffective. In fact, stopping smoking still significantly lowers the risk of many serious illnesses and improves quality of life. Instead, the study says that the lungs may not return completely to the condition they were in before smoking began. This underlines the importance of quitting as early as possible and staying smoke-free while continuing regular health check-ups, especially for people who smoked for many years.

What Did The New Study Find?

The study, published in Translational Research, analysed lung tissue from current smokers, former smokers, and people who had never smoked. Researchers used advanced genetic techniques to examine how individual lung cells behaved after smoking cessation.

They discovered that some lung cells gradually returned to a healthier state once smoking stopped. However, many other cells continued to show long-lasting changes in genes involved in tissue repair, immune function, inflammation, and blood vessel health. These persistent changes may explain why former smokers remain at a higher risk of lung diseases such as chronic obstructive pulmonary disease (COPD) and lung cancer, even years after quitting.

Can The Lungs Heal After Quitting Smoking?

Yes, the lungs do begin to heal after quitting smoking, but recovery has its limits. Within a few weeks, tiny hair-like structures called cilia, which help remove mucus and harmful particles from the lungs, start working more effectively again. Lung inflammation also reduces, making it easier to breathe. Over time, lung function may improve, especially in people who quit before significant damage has occurred.

However, not all smoking-related damage can be reversed. If smoking has destroyed air sacs (alveoli) or caused permanent scarring, those changes cannot be completely repaired. This is why some former smokers continue to experience breathlessness or reduced lung function despite giving up cigarettes.

Carolyn Baglole, senior author, Professor in McGill's Department of Pharmacology and Therapeutics and researcher, Research Institute of the McGill University Health Centre, said, "Current smokers have the highest risk of deadly diseases such as lung cancer, but former smokers still face a higher risk than people who never smoked. Despite more than a century of research on smoking, we don't fully understand why. Our findings show that while some damage appears reversible, other changes persist long after people stop smoking."

Why Do Former Smokers Still Face Health Risks?

Smoking exposes the lungs to thousands of harmful chemicals that damage cells and their DNA. Although quitting prevents further exposure, some of these damaged cells remain in the lungs.

According to the new study, these lingering cellular changes may continue to affect how lung tissue repairs itself and responds to inflammation. As a result, former smokers remain at a higher risk of developing conditions such as COPD, emphysema, and lung cancer compared to people who have never smoked. The risk does decrease after quitting but does not disappear entirely.

Does This Mean Quitting Smoking Is Too Late?

Absolutely not. Experts stress that quitting smoking is beneficial at any age. The body begins to recover almost immediately after the last cigarette. Heart rate and carbon monoxide levels improve within hours, circulation gets better over the following months, and the risks of heart disease, stroke, and several cancers continue to decline over time.

Even if some lung damage cannot be reversed, quitting slows further damage, improves breathing, reduces symptoms, and increases life expectancy. People who stop smoking also lower the risk of exposing family members to harmful secondhand smoke.

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